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This conference will be dedicated to imaging, sensing, monitoring and spectroscopy based on the combination of light and sound by synergistically utilizing the high optical contrast and the high ultrasonic resolution at large tissue depths. The images based on optical contrast are complementary to images based on ultrasonic contrast. The hybrid technology such as optoacoustic/photoacoustic tomography can provide anatomical and functional imaging for comprehensive tissue characterization. It is also capable of providing high-resolution molecular imaging. The areas of interest include methods involving optically and thermally induced acoustic waves and acoustically modulated optical waves and a variety of laser-induced thermal and acoustic phenomena, covering basic research, instrumentation and applications. Biomedical applications include cancer detection, localization, and differentiation, detection of atherosclerotic plaques, vascular imaging and angiography.

Topics that involve a combination of light and sound include: All submissions will be reviewed by the Program Committee to determine acceptance. Extended abstracts will be used only for the purpose of review and will not be published.

Post-deadline submissions may be accepted contingent upon confirmation of exceptional quality of research as determined by the Program Committee.

Best Paper Award and Best Poster Award
Seno Medical Instruments of San Antonio, Texas, will sponsor the "Best Paper Award" at this conference (Certificate of recognition to all coauthors and $3,000 cash award).
Photoacoustics Journal, Elsevier, will sponsor the “Best Poster Award” at this conference (Certificate of recognition to all coauthors and $1,500 cash award).

To qualify for the Award, authors must submit a 2-page extended abstract at the time of Abstract submission, present their papers at the conference (oral or poster) and publish a full manuscript in the SPIE Proceedings. A special session will be organized at the conference dedicated to The Best Paper and The Best Poster Awards. A Certificate of The Best Paper or The Best Poster will be presented at the Award Ceremony to be held as the last session of the Conference. Cash award will be delivered after the publication of the conference proceedings volume.

Submissions to this conference include the following:
  • 100 word text abstract (for online program) (REQUIRED)
  • 250-word text abstract (for technical review) (REQUIRED)
  • Optional 2-page extended abstract (this option makes submissions eligible for the Best Paper or the Best Poster award nominations). The extended abstract must be submitted as a separate PDF document limited to two pages, including tables and figures. Include author names and affiliations; text; any figures, tables, or images; and sufficient data to permit committee review.
In progress – view active session
Conference 11960

Photons Plus Ultrasound: Imaging and Sensing 2022

In person: 23 - 26 January 2022
View Session ∨
  • 1: In Vivo Human Imaging
  • 2: Ex Vivo, Blood, Cell Studies
  • 3: Small-Animal Imaging I
  • 4: Small-Animal Imaging II
  • 5: Awards Competition I
  • 6: Awards Competition II
  • 7: Awards Competition III
  • 8: Awards Competition IV
  • 9: Laser Ultrasound
  • 10: Novel Systems Including Wavefront Shaping
  • 11: Advances in Phantoms and Phantom Studies
  • 12: Contrast Agents, Molecular and Quantitative Imaging
  • 13: Machine Learning: Developments and Applications
  • 14: Optical Sensing of Pressure/Displacement
  • 15: Advances in Ultrasound Detection
  • 16: Advances in Endoscopy and Microscopy
  • 17: Signal and Image Processing
  • Posters


  • Submissions are accepted through 06-December
  • Notification of acceptance by 20-December

View Call for Papers PDF Flyer
Session 1: In Vivo Human Imaging
Author(s): Maura Dantuma, Multi-Modality Medical Imaging group, University of Twente (Netherlands); Laurens Alink, Rutger P. Pompe van Meerdervoort, P.A. Imaging B.V. (Netherlands); Bradley Treeby, Department of Medical Physics and Biomedical Engineering, University College London (United Kingdom); David Thompson, Multi-Modality Medical Imaging group (Netherlands), Biomedical Photonic Imaging group, University of Twente (Netherlands); Michael Jaeger, Martin Frenz, Biomedical Photonics group, University of Bern (Switzerland); Ben Cox, Department of Medical Physics and Biomedical Engineering, University College London (United Kingdom); Srirang Manohar, Multi-Modality Medical Imaging group, University of Twente (Netherlands)
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We present a hybrid multispectral photoacoustic-ultrasound breast tomographic imager, called the PAMMOTH system, designed for diagnostic applications in breast cancer. A detailed overview of the system is provided, and its functionalities and its imaging capability are demonstrated on healthy volunteers. With photoacoustics, we obtain high resolution depiction of the vascular anatomy deep in the breast. The sound speed images improve the accuracy of the photoacoustic reconstruction and provide morphological information which help interpretation of the PA images.
Author(s): Sitai Kou, Xiandong Leng, Quing Zhu, Washington Univ in St. Louis (United States)
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Post-treatment monitoring of rectal cancer (RC) is limited by the lack of sensitive imaging modality, hindering the application of the novel “watch and wait” strategy. Photoacoustic microscopy co-registered with US (PAM/US) has shown promise in RC treatment response assessment. However, MRI-guided PAM/US offers a feasible solution for full rectum examination. In this study, we report MRI-guided PAM/US results. Patients were imaged with MRI preoperatively and tumor beds were located on MRI sagittal views. PAM/US scan was performed and automatically analyzed by a convolutional neural network (CNN) for residual cancer probability. This new combination of imaging modalities has the potential to offer accurate evaluation of post-treatment response of RC.
Author(s): Joongho Ahn, Changyeop Lee, Moongyu Han, Eun-Yeong Park, Byullee Park, Seonghee Cho, Seungwan Jeon, Chulhong Kim, Pohang Univ of Science and Technology (Korea, Republic of)
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We present a contour-scan-based volumetric PA/US foot imaging system for structural and quantitative evaluation of the vasculature. To minimize the effect of the optical fluence, we compensate the PA images using the background PA signals that represent optical attenuation in the tissue. To evaluate its capability to provide functional information of the vasculature, we demonstrate a quantitative evaluation of the peripheral vasculature before and after external blood flow occlusion with a pressure cuff. We confirmed the potential of the technique for providing a diagnostic evaluation of the peripheral vasculature.
Author(s): Lei Fu, Univ of California San Diego (United States)
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Periodontitis is a big public health problem. Its primary feature is the clinical attachment loss (CAL), which can be qualified by measuring the pocket depth by using a periodontal probe. In this work, we use photoacoustic tomography as an alternative tool to qualify the pocket depth. We measured the pocket depth of 40 swine teeth by using the William periodontal probe and photoacoustic imaging. The two groups of measurements are highly correlated. We also imaged the pocket areaof human first molars. Our studies proved that photoacoustic imaging can be used as a clinical tool to measure the pocket depth.
Author(s): Neda Davoudi, Berkan Lafci, Ali Ozbek, Xosé Luís Deán-Ben, ETH Zurich (Switzerland), University of Zurich (Switzerland)
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Optoacoustic images are often afflicted with distortions and artifacts corresponding to system limitations, including limited-view tomographic data. We developed a convolutional neural network (CNN) approach for optoacoustic image quality enhancement combining training on both time-resolved signals and tomographic reconstructions. Reference human finger data for training the CNN were recorded using a full-ring array system with optimal tomographic coverage. The reconstructions were further refined with a dedicated algorithm that minimizes acoustic reflection artifacts induced by acoustically mismatch structures, such as bones. The combined methodology is shown to outperform other CNN-based methods solely operating on image-domain data.
Author(s): Ashkan Javaherian, University College London (United Kingdom); Felix Lucka, Computational Imaging group, Centrum Wiskunde en Informatica (Netherlands); Maura Dantuma, Multi-Modality medical imaging group, TechMed Centre, University of Twente (Netherlands); Rianne Bulthuis, Multi-Modality medical imaging group (Netherlands); Laurens Alink, R.P. Pompe van Meerdervoort, P.A. Imaging B.V. (Netherlands); Jakub Budiský, Department of Computer Systems, Faculty of Information Technology, Brno University of Technology (Czech Republic); Andrejus Michailovas, Ekspla uab (Lithuania); Srirang Manohar, Multi-Modality medical imaging group (Netherlands); Jiri Jaros, Department of Computer Systems (Czech Republic); Bradley Treeby, Biomedical ultrasound group, University College London (United Kingdom); Ben Cox, Biomedical ultrasound group (United Kingdom)
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This study demonstrates a fast, time-of-flights-based (TOF) approach for full-3D reconstruction of the sound speed from ultrasound data collected with the hybrid photoacoustic/ultrasound PAMMOTH scanner. TOF-based approaches iteratively fit the integral of slowness along the rays linking emitter-receiver pairs to the TOFs of the measured time traces. Our approach uses a novel, derivative-free iterative 3D ray-linking scheme for a fast computation of the trajectory of rays. We demonstrate the impact of using the reconstructed sound speed images for aberration correction in photoacoustic tomography with in-vivo data instead of using two homogenous sound speed for breast and water.
Author(s): Sitai Kou, Xiandong leng, Quing Zhu, Washington Univ in St. Louis (United States)
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Efficient early-stage screening for ovarian cancer, which is the deadliest cancer of all gynecologic malignancies, remains a big challenge. Optical resolution photoacoustic microscopy (OR-PAM) has been investigated for its role in diagnosis of ovarian cancer. However, data of the complex microscopic vasculature distribution of human ovary and fallopian tube remains scarce. In this study, we report initial results of ovarian and fallopian tube vasculature quantification obtained from 18 normal ovaries and 19 fallopian tubes and 3 cancerous ovaries and fallopian tubes. Our results demonstrate statistical significance between the normal ovarian tissue and normal fallopian tubes, and show chaotic patterns of cancerous ovaries and fallopian tubes.
Session 2: Ex Vivo, Blood, Cell Studies
Author(s): Nathaniel J. M. Haven, Matthew T. Martell, Brendyn D. Cikaluk, Brendon S. Restall, Roger J. Zemp, Univ of Alberta (Canada)
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Currently, there is an inability to obtain fast realistic label-free virtual histopathological images of tissues. We previously introduced ultraviolet photoacoustic remote sensing microscopy as a method to obtain virtual hematoxylin contrast albeit without the ability to obtain virtual eosin contrast. By utilizing UV scattering as a high-resolution eosin channel we are able to produce complete H&E-like virtual histology of unstained human breast lumpectomy specimen sections. By further leveraging a novel colormap matching algorithm with this UV scattering, we generate H&E-like output that is shown to have strong concordance with true H&E-stained adjacent sections, showing promising diagnostic utility.
Author(s): Matthew T. Martell, Nathaniel J.M. Haven, Brendon S. Restall, Roger J. Zemp, Univ of Alberta (Canada)
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A combined synthetic aperture optical coherence microscopy and ultraviolet photoacoustic remote sensing system is presented, capable of fast scanning of tissues for tumor margin inspection. It provides a fast 3D OCT mode for imaging tissues to depths of ~1mm, and a superficial virtual histology mode provided by absorption contrast UV-PARS for virtual hematoxylin contrast and coherence-gated scattering microscopy for virtual eosin contrast. Breast lumpectomy specimens are scanned in each mode to evaluate the extent of features in depth and generate en-face images with histological detail and realism, providing results accurately interpretable by pathologists.
Author(s): Guan Xu, Univ of Michigan Kellogg Eye Ctr (United States); Linyu Ni, Wei-Kuan Lin, Javed Siddiqui, L. Jay Guo, Xueding Wang, Aaron Udager, University of Michigan (United States)
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This study examined the performance of a clinical translatable needle photoacoustic sensing probe in intact prostates removed through prostatectomy procedures. Compared to the prototype probe in our previous studies, the latest version probe possesses fiber optic hydrophone with a dome-shaped tip that provides better sensitivity and sampling volume. The optical components were integrated into a customized clinical standard steel needle with a side opening and protected by medical grade polyurethane. The needle probe was examined in a setup mimicking a transrectal ultrasound guided transperineal prostate biopsy procedure. Preliminary tests showed promising results in differentiating between benign and aggressive cancer tissues in prostate.
Author(s): Filip J. Bodera, Michael Kolios, Ryerson Univ (Canada)
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Clotting is measured by assessing changes in viscoelasticity or optical density in blood/plasma. While these methods provide insights if a patient has an imbalance of clotting factors, viscoelasticity requires blood volumes that are not always attainable and plasma measurements do not account for cellular contributions. A photoacoustic imaging system with a 532nm laser and a 40MHz transducer was used to image samples in microtiter plates. Blood clots were formed and lysed using clotting factors and enzymes in reconstituted human blood. Frequency analysis showed fluctuations in whole blood but were consistent in clotting blood, indicating dependence of RBC spatial arrangement.
Author(s): Phuc Nguyen, Univ of Michigan-Kellogg Eye Ctr. (United States); Wen Fan, Department of Ophthalmology, Jiangsu Province Hospital and Nanjing Medical University First Affiliat (United States); Wei Qian, IMRA America Inc. (United States); Yanxiu Li, Univ of Michigan-Kellogg Eye Ctr. (United States); Wei Zhang, Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48105, USA (United States); Bing Liu, IMRA America Inc. (United States); Jessica Henry, Univ of Michigan-Kellogg Eye Ctr. (United States); Xueding Wang, Department of Biomedical Engineering (United States)
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The aim of this study is to address the feasibility of an advanced multimodal photoacoustic microscopy (PAM), optical coherence tomography (OCT), and fluorescence imaging (FI) system for longitudinal tracking of stem cells in the posterior segment of the retina. A precursor human retinal pigment epithelial cell line (ARPE-19) cells were cultured with novel ultrapure chain-like cluster gold nanoparticles (CGNPs) which have the plasmonic absorption peak shifted to the near-infrared window (650 nm), resulting in enhanced visualization of transplanted cells from strong background signal generated by hemoglobin. The cells labeled with CGNPs were transplanted into the subretinal space of the rabbit retina having focal retinal photocoagulation laser injury and were monitored longitudinally over a period of 3 months. These results may provide a promising image-guided stem cell treatment for different applications in regenerative medicine.
Author(s): Yueming Li, Ying Jiang, Lu Lan, Xiaowei Ge, Yuewei Zhan, Linli Shi, Chen Yang, Ji-xin Cheng, Boston University (United States)
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Transcranial focused ultrasound (tFUS) prefers low ultrasonic frequency for its high transcranial efficiency, but the spatial resolution is limited to millimeters. Here, we report non-invasive high precision neuromodulation using optical-driven focused ultrasound (OFUS). OFUS optoacoustic emitter was fabricated by embedding candle soot nanoparticles in a polydimethylsiloxane spherical surface. OFUS reached a high spatial resolution of ~ 60 µm, which is two orders-of-magnitudes smaller than that of the tFUS. Using OFUS, we achieved direct and transcranial in vitro stimulation of cortical neurons with single laser pulse excitation and validated successful non-invasive in vivo stimulation by immunofluorescence staining and electromyography recording.
Session 3: Small-Animal Imaging I
Author(s): Chulhong Kim, Jaewoo Kim, Joongho Ahn, Pohang Univ of Science and Technology (Korea, Republic of)
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To evaluate the utility of PA in imaging the GI tract in large animals, we conducted a feasibility study using the porcine gastric wall ex vivo. We used fresh pig stomachs within hours of sacrifice and successfully acquired multispectral images of the vasculature of the porcine gastric wall layer ex vivo. Imaging proceeded with samples of the entire stomach layer, including the mucosa, submucosa, muscularis externa, and serosa. It was possible to acquire the vascular signal up to 1.9 mm depth from the mucosal surface, which could cover the entire mucosa and submucosa.
Author(s): Kai-Wei Chang, Univ of Michigan (United States); Yunhao Zhu, Nanjing University (China); Xinmai Yang, University of Kansas (United States); Xueding Wang, Univ of Michigan (United States)
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The feasibility of using photoacoustic imaging (PAI) to measure electrically-evoked hemodynamic responses in a squirrel monkey brain in vivo was examined. A linear-array photoacoustic computed tomography (PACT) system and a high-resolution photoacoustic microscopy (PAM) system were built for imaging subcortical and cortical brain regions, respectively. The hemodynamic responses at multiple cortices, including premotor, primary motor, and primary somatosensory cortices, were monitored. The variations could be observed in all cortices and their underlying cortical and subcortical brain regions. The results from this study validated the potential of PAI technique for multiscale and multi-resolution functional brain mapping for non-human primates.
Author(s): Sandeep Kumar Kalva, Xose Luis Dean-Ben, Univ of Zurich (Switzerland), ETH Zurich (Switzerland)
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Accurate visualization of biological events at scales in the order of seconds requires high frame rate acquisition of image data from living tissues. Yet, fast imaging performance commonly comes at the cost of limited field-of-view (FOV) and reduced image quality. Here we present single-sweep volumetric optoacoustic tomography (sSVOT) for whole-body imaging of mice from head to tail within 1.8 s. sSVOT capitalizes on a custom-made spherical matrix array transducer together with a multi-beam illumination approach, the latter playing a critical role in maximizing the effective FOV. We compare the performance metrics to the previously reported whole-body mouse imaging implementations.
Author(s): Russell w. Chan, Sarah Shaykevich, New York University Grossman School of Medicine (United States); Daniel Razansky, University of Zurich and ETH Zurich (Switzerland); Shy Shoham, New York University Grossman School of Medicine (United States)
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The glymphatic system is a brain waste clearance system mediated via cerebrospinal fluid (CSF) flow. Fluorescence imaging and MRI are used in most preclinical glymphatic studies. Functional optoacoustic neuro-tomography (FONT) offers deeper penetration and larger field-of-view compared to classical optical methods and higher specificity compared to MRI. However, applying FONT to probe CSF flow dynamics has not been attempted to date. In this study, we confirmed distinct optoacoustic signature of the novel near-infrared dye JF669 and used it to demonstrate the feasibility of probing CSF flow dynamics with FONT, possessing great opportunities for monitoring and understanding the glymphatic system.
Author(s): Nima Abbasi Firoozjah, Nicholas Pellegrino, Layla Khalili, Parsin Haji Reza, Univ of Waterloo (Canada)
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In this work, a synchronized dual-modal imaging system is used for in-vivo, non-contact ophthalmic imaging. The apparatus is comprised of both Photoacoustic Remote Sensing (PARS) and Swept-Source Optical Coherence Tomography (SS-OCT) subsystems. The PARS utilizes a multi-wavelength excitation source to target hemoglobin absorption and an 830 nm interrogation source to detect photoacoustic signals. PARS provides the measurements for computing blood oxygen saturation (sO2) mapping in the mouse and rat eyes. Meanwhile, a 1060 nm SS-OCT is employed to obtain volumetric tissue structure. To our knowledge, this is the first report of non-contact functional photoacoustic imaging in ophthalmic applications.
Author(s): Abigail Claus, Marvin Xavierselvan, Srivalleesha Mallidi, Tufts Univ (United States)
Author(s): Eno Hysi, Xiaolin He, Darren A. Yuen, St. Michael's Hospital (Canada); Michael C. Kolios, Ryerson Univ (Canada)
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This work demonstrates an algorithm for respiratory-corrected photoacoustic imaging of oxygen saturation and collagen in mouse kidneys and livers.
Session 4: Small-Animal Imaging II
Author(s): Eno Hysi, Xiaolin He, St. Michael's Hospital (Canada); Michael C. Kolios, Ryerson Univ (Canada); Darren A. Yuen, St. Michael's Hospital (Canada)
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We show how a motion-corrected photoacoustic imaging algorithm can be used to monitor kidney damage from ischemia-reperfusion injury (IRI) in-vivo. This work can potentially monitor the outcome of preclinical IRI-reversing drugs in rodent models.
Author(s): Marvin Xavierselvan, Tufts Univ (United States); Jason Cook, Nanohybrids Inc (United States); Srivalleesha Mallidi, Tufts Univ (United States)
Author(s): Francis Kalloor Joseph, Wiendelt Steenbergen, Univ of Twente (Netherlands)
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Stromal cells play an active role in tumor proliferation, invasion, and metastasis. Studying the influence of tumor stroma can help to develop targeted therapy. We present a photoacoustic imaging-based study of tumor stroma. We induced tumors in the mice, with tumor cells alone in the first group and with tumor cells added with fibroblast cells in the second. We performed photoacoustic imaging at 850 nm wavelength to access the blood content in the tumor and 1200, 1300, and 1500 nm wavelengths to estimate the collagen distribution and validate using histology analysis. Results show blood and collagen distribution quantifying tumor stroma.
Author(s): Liron McLey, Technion - Israel Institute of Technology (Israel); Daniel Razansky, Institute for Biomedical Engineering, University of Zurich and ETH Zurich (Switzerland); Shy Shoham, Neuroscience Institute, Tech4Health Institute and Department of Ophthalmology, New York University (United States)
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Optoacoustic tomography methods can image large volumes at high rates and are thus potentially uniquely suitable for the visualization of distributed brain activity. We developed a functional optoacoustic neuro-tomography (FONT) experimental system capable of imaging the mouse brain during visual stimulation. We imaged GCaMP6-expressing mice using two complementary wide-field fluorescence imaging paradigms, enabling sequential or simultaneous optoacoustic and fluorescence imaging. Using our results and a new analysis pipeline, we robustly identify, characterize and decouple the fluorescence signatures of visually-evoked and characteristic spontaneous neural events, and explore the functional optoacoustic signature of these responses.
Author(s): Kristie Huda, Dylan J. Lawrence, Carolyn Bayer, Tulane Univ (United States)
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We have developed methods to use photoacoustic tomography to assess vasoactivity in multiple vascular beds of living animals noninvasively. A spherical-view photoacoustic tomography system was used to monitor acute vasodilation in the whole abdomen of a pregnant mouse in response to injection of G-1. After 3D image reconstruction, the diameter of the iliac artery and photoacoustic signal intensity of a placenta over time was measured. The artery and placenta responded to the G-1 injection with different peak response times. We validated this observed vasodilation by monitoring the change in cross-sectional diameter of an individual artery using standard B-mode ultrasound imaging.
Author(s): Rinat O. Esenaliev, Auston Grant, Adelaide Micci, Univ of Texas Medical Branch (United States)
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Recently we proposed optoacoustic therapy/Nano-Pulse Laser Therapy (NPLT) and demonstrated its therapeutic effects in rats with acute traumatic brain injury (TBI). Here we studied the ability of NPLT to reduce chronic inflammation when administered months after TBI. NPLT was delivered transcranially at 808 nm for 5 minutes daily (5x per week) starting at 2 months post-injury for a total of 4 weeks. It significantly (3 to 4-fold) reduced: 1) the number of CD68+ microglia in the thalamus and somatosensory cortex; and 2) astrogliosis in these brain areas. Our data support the therapeutic potential of NPLT for chronic TBI patients treatment.
Session 5: Awards Competition I
Author(s): Changyeop Lee, Seonghee Cho, Chulhong Kim, Pohang Univ of Science and Technology (Korea, Republic of)
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We updated a clinical photoacoustic (PA)/ultrasound(US) handheld scanner and an imaging system to enhance clinical usability and enable wide-field volumetric PA/US imaging. The scanner was optimized for the weight and dimensions of 600 g and 70 × 62 × 110 mm3, respectively, which is 60 and 63 % of the previous scanner, respectively. The imaging system enabled online maximum amplitude projection (MAP) imaging, which provided images of n × 25 × 38 mm2, where n is the number of scans. We believe that the system and scanner can be useful for a variety of clinical applications.
Author(s): Thomas J. Allen, Edward Zhang, Paul Beard, Univ College London (United Kingdom)
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Standard Fabry-Perot (FP) based scanners are typically interrogated by scanning a focused laser beam over its surface and measuring the reflected light. An alternative is to illuminate the FP sensor with a large collimated beam and measure the reflected light using a camera. This would allow the speeding up of image acquisition. To investigate this approach, a system was built and its ability to acquire full 3D photoacoustic images in times as low as 0.2 seconds demonstrated in phantoms. It was then used for in-vivo photoacoustic imaging, demonstrating the ability of the system to rapidly acquire images of the microvasculature.
Author(s): Benjamin Keenlyside, Dylan Marques, Maxim Cherkashin, Peter Munro, Edward Zhang, Paul Beard, James Guggenheim, Univ College London (United Kingdom)
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Performing high resolution Photoacoustic Tomography (PAT) endoscopically could unlock a range of biomedical and clinical applications. However it is challenging to miniaturize traditional piezoelectric detector arrays enough for endoscopic use. We therefore propose an alternative approach, performing all-optical PAT through a multimode fiber by using wavefront shaping to scan an optical focus across a polymer film Fabry-Perot ultrasound sensor array. This approach is found to be effective, and paves the way to developing a new range of clinical endoscopic instruments offering several advantages over the current state of the art, including increased miniaturization, reduced probe cost, and greater endoscope reach.
Author(s): Shuai Na, Lihong Wang, Caltech (United States)
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We propose a hybrid imaging method combining cross-ray ultrasound tomography (CRUST) and photoacoustic computed tomography (PACT) to simultaneously monitor blood flows and hemoglobin concentrations during functional studies. Unlike conventional functional ultrasound imaging, CRUST employs a standalone focused ultrasonic transducer for wide-field excitation and a panoramic transducer array for detection. The transmission and detection acoustic rays are crossed, permitting omnidirectional sensitivity to the blood flows. We integrated CRUST with an established PACT system to reveal vector blood flows and hemoglobin concentrations of the mouse brain under stimulation, demonstrating CRUST-PACT as a unique tool for neuroimaging.
Author(s): Xiaoyi Zhu, Junjie Yao, Duke University (United States)
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We present a new functional photoacoustic microscopy system with the highest imaging speed and ultrawide field of view. The high imaging speed is enabled by a 12-facets polygon for fast scanning and a Raman-shifter system for fast dual-wavelength measurement of oxygen saturation in vivo. we imaged the dynamic functions in mouse brains in response to hypoxia challenge, sodium nitroprusside (SNP), and ischemic stroke. The experimental results have demonstrated that the high-speed photoacoustic microscopy system can be a powerful tool for studying the rapid hemodynamics in the mouse brains of a wide range of pathological and physiological models.
Author(s): Jiaqi Zhu, Ciaran Bench, Ben Cox, Paul Beard, Univ College London (United Kingdom)
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Deep learning approaches can be implemented to estimating blood oxygen saturation (sO2) using spectroscopic photoacoustic imaging without reference to a physical model and thus can be more accommodating of incomplete knowledge of the relevant imaging physics. However, they pose a challenge, namely the requirement for high quality training data with an accurate ground truth. The challenge is particularly pressing for convolutional networks that use photoacoustic images as inputs to learn sO2 because they require high quality simulated training images that accurately replicate these features and this represents a non-trivial challenge. The aim of the study was to assess the scale of this challenge using a convolutional network that used 3D multiwavelength photoacoustic images as inputs.
Author(s): Fernando Perez-Cota, Salvatore La Cavera, Richard J. Smith, Matt Clark, Nottingham University (United Kingdom)
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Characterisation of the elasticity of biological cells is growing as a new way to gain insight into cell biology. Cell mechanics are related to most aspects of cellular behaviour, and applications in research and medicine are broad. However, the techniques for this purpose are often limited since they lack resolution or require physical contact and therefore, are destructive. Here, we present new developments of picosecond ultrasonics for cell imaging and characterisation using GHz sound. In particular, we present developments in methods based in time-resolved Brillouin scattering and super-resolution phononic imaging of nanostructures for cell imaging applications.
Session 6: Awards Competition II
Author(s): Michael Nagli, Technion Israel Institute of Technology (Israel); Jürgen Koch, Laser Zentrum Hannover e.V. (Germany); Yoav Hazan, Resmi Ravi Kumar, Ahiad Levi, Evgeny Hahamovich, Technion Israel Institute of Technology (Israel); Ludger Overmeyer, Laser Zentrum Hannover e.V. (Germany); Amir Rosenthal, Technion Israel Institute of Technology (Israel)
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One of the challenges of optoacoustic microscopy is its bulky apparatus, which limits minimally invasive applications. While optical detection of ultrasound provides sufficient miniaturization, this approach generally lacks acoustic focusing, making it incompatible with applications such as intravascular imaging. This work demonstrates a sub-millimeter focused ultrasound detector based on a silicon-photonics sensor bonded to an acoustic lens, achieving a lateral resolution of 50 µm. Furthermore, we experimentally demonstrated artifact-free imaging of complex phantoms by employing an acoustically absorbing composite material to remove stray acoustic waves emanating from outside the focal region of the detector.
Author(s): Shensheng Zhao, Bing-Ze Lin, Univ. of Illinois (United States); Hsuan‐Kai Huang, Yang Zhao, Yun-Sheng Chen, Department of Electrical and Computer Engineering at UIUC (United States)
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Ultrasound localization microscopy (ULM) maps the locations of moving microbubbles to form a super-resolution image. However, the speed of ULM is slow because it requires thousands of ultrasound images to form one ULM image. We develop a fast photoactive ultrasound localization microscopy (pULM) using laser-activatable nanodroplets as alternative contrast agents. The nanodroplets allow both temporally- and spatially- selective vaporization of nanodroplets into microbubbles. We use block-wise localization with sparsity constraints optimization to improve the localization recovery efficiency significantly from densely packed activated-nanodroplets (microbubbles). With these techniques, we demonstrate an in vivo fast super-resolution imaging in a small animal model.
Author(s): Rui Cao, Yide Zhang, Lihong V. Wang, California Institute of Technology (United States)
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Intraoperative pathology is widely used for tumor margin detection in oncology surgery. However, it has been a long-standing challenge for orthopedic oncologists due to the difficulty of bone frozen sectioning. To address this critical need, we have developed contour-scanning ultraviolet photoacoustic microscopy (UV-PAM) for intraoperative pathological examination of unprocessed bone specimens with rough surfaces. The UV-PAM of both decalcified and undecalcified bone specimens were compared with traditional histology images via hematoxylin and eosin (H&E) staining for validation. In addition, we demonstrated the UV-PAM pseudocolor virtual histology via an unsupervised deep learning method based on cycle-consistent generative adversarial networks (CycleGAN).
Author(s): Yizhi Liang, Long Jin, Xiaoxuan Zhong, Bai-ou Guan, Jinan Univ (China)
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Fiber optics can significantly reduce the weight of the PAM to only 6 grams while having functional imaging capability. With the fiber-based PAM, we demonstrate the functional imaging result of the brain oxygen metabolism of a freely moving mouse under epinephrine challenge, with an imaging area of 1.2×1.2 mm2, an A-line rate of 500 kHz, and a frame rate of 1 Hz.
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Following resection of cancerous tissues, specimens are excised from the surgical margins to be examined post-operatively for the presence of residual cancer cells. Hematoxylin and eosin (H&E) staining is the gold standard of histopathological assessment. Ultraviolet photoacoustic microscopy (UV-PARS), combined with scattering microscopy, provides virtual nuclei and cytoplasm contrast similar to H&E staining. A generative adversarial network (GAN) deep learning approach, specifically a CycleGAN, was used to perform style transfer to improve the histological realism of UV-PARS generated images. Post-CycleGAN images are easier for a pathologist to examine and can be input into existing machine learning pipelines for H&E-stained images.
Author(s): Joongho Ahn, Jinwoo Baik, Yeonggeun Kim, Jin Young Kim, Hyung Ham Kim, Chulhong Kim, Pohang Univ of Science and Technology (Korea, Republic of)
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Photoacoustic microscopy (PAM) has been used in microvascular imaging. Here, we developed a high-resolution, high-speed PAM using a ring-shaped flat ultrasound transducer and a parabolic mirror rotated by a galvanometer scanner, and incorporated photoplethysmography (PPG) into this PAM. Using the PAM, vascular images were acquired in human cuticle with a capillary resolution. With the PAM and PPG, vascular images and blood volume were obtained in human finger. Then two identical heart rates were extracted from vascular movements and blood volume changes. From these results, we believe that the PAM could be potentially used to provide vascular images and heart rate.
Session 7: Awards Competition III
Author(s): Benjamin R. Ecclestone, Kevan Bell, Nicholas Pellegrino, Parsin Haji Reza, Univ of Waterloo (Canada)
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The second generation of virtual histological imaging with Photoacoustic Remote Sensing (PARS) microscopy is presented. PARS captures label-free absorption contrast in an all-optical reflection-mode architecture enabling label-free histology of resected tissues. A new 2.7 MHz excitation PARS microscope, with hybrid opto-mechanical scanning provides 3-dimensional imaging and scanning of entire tissues sections in minutes. Concurrently, a novel detection architecture and signal processing scheme provide improved sensitivity, and resolution. Exemplified in resected human tissues, PARS visualizes cell nuclei, connective tissues, lipids, and more with contrast and quality analogous to traditional histological preparations. This represents a milestone in the development of a clinically deployable PARS microscope.
Author(s): Lei Li, Lihong Wang, Cal Tech (United States)
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Photoacoustic tomography with genetically encoded near-infrared probes enables visualization of specific cell populations in vivo at high resolution in deep tissues. Here, we report a near-infrared Forster resonance energy transfer biosensor based on a pair of the near-infrared fluorescent proteins, miRFP670-iRFP720, which enables dynamic photoacoustic imaging of active biological processes. Specifically, we detected apoptosis in single cells at a resolution of ~3 µm in a mouse ear and mouse brain tumors (>3 mm in depth) at a spatial resolution of ~150 µm. These results open the way for high-resolution photoacoustic imaging of dynamic biological processes in deep tissues.
Author(s): Xiandong Leng, Eghbal Amidi, Sitai Kou, Will Jr Chapman, Matthew Mutch, Quing Zhu, Washington Univ in St. Louis (United States)
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A co-registered photoacoustic microscopy/ultrasound system (US/PAM) is developed to acquire images from rectums of patients after radiation and chemotherapy. The hypothesis is that deep-learning based convolution neural network (CNN) outperforms traditional histogram-feature based classifiers in predicting residual tumors. To test the hypothesis, we trained generalized linear models (GLM) using histogram features of US and PAM images. We compare the performance of these classifiers with CNN models that are trained from US and PAM images. It is shown that CNN models developed using PAM images substantially outperforms GLM classifier trained using PAM histogram features (Area Under ROC of 0.96 vs 0.82).
Author(s): Wei Zhang, Univ of Michigan Medical School (United States); Ibrahim Oraiqat, Moffitt Cancer Center (United States); Kaiwei Chang, Noora Ba Sunbul, Dale Litzenberg, Xueding Wang, Univ of Michigan Medical School (United States)
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Ironizing radiation acoustic imaging (iRAI) is a novel imaging concept with the potential to map the radiation dose delivery in real time during external beam radiation therapy. In this study, iRAI volumetric dose mapping was achieved with 2D matrix transducer array using a C-shape 3D conformal treatment plan with clinically relevant setting and a moving beam plan in both phantoms and rabbit model in vivo. With the unique ability to map the volumetric dose delivery in real time, iRAI 3D dose mapping can be developed into a new tool for quantifying the accuracy of dose delivery of radiation therapy.
Author(s): Yoav Hazan, Ahiad Levi, Michael Nagli, Amir Rosenthal, Technion Israel Institute of Technology (Israel)
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A new ultrasound-detection technology is developed for ultrahigh-resolution optoacoustic tomography and is experimentally demonstrated with bandwidths exceeding 200 MHz and lateral resolutions beyond 20 µm. Our technology is based on an optical resonator fabricated in a silicon-photonics platform, which is coated by a sensitivity-enhancing polymer, which also eliminates the parasitic effect of surface acoustic waves. Further improvement in sensitivity is achieved by a low-noise interferometric setup, which eliminates the effect of laser frequency noise on the measurement. In vivo optoacoustic tomography is performed on a mouse ear, revealing its vasculature at detail that has been previously reserved to optoacoustic microscopy.
Author(s): Kai-Wei Chang, Univ of Michigan (United States); Yunhao Zhu, Nanjing University (China); Xueding Wang, Guan Xu, Univ of Michigan (United States)
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The current functional brain mapping techniques such as fMRI and DOI suffer from limited spatial resolution. Photoacoustic (PA) imaging combines the sensitivity of optical imaging to hemodynamic variations, and spatial resolution of ultrasound detection. In this study, we built a label-free PA computed tomography (PACT) system with a ring-shaped ultrasound array to monitor the hemodynamic changes in the primary visual cortex (V1) of mice in response to retinal photostimulation. The responses of wild-type and retinal degenerate (rd1) mice were compared. A linear-array PACT system was also used to measure the visually-evoked subcortical responses. Therefore, PACT is potential tool to study the effect of retinal degeneration of mice on the visual pathway.
Author(s): Weylan Thompson, Hans-Peter Brecht, Sergey A. Ermilov, Vassili Ivanov, PhotoSound Technologies Inc (United States)
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We present the continued development a clinical ultrasound (US) imaging device with a photoacoustic (PA) mode. The combined USPA imaging platform is designed around a compact US component capable of B-mode, M-mode, color Doppler, and pulsed wave Doppler US imaging modes with a 128 element US probe. The PA mode can support a 256 element PA probe with real-time 2D imaging up to 20 Hz. The PA signals are amplified by a 40 dB pre-amplifier while US mode signals bypass the circuit, resulting in high quality PA images. We demonstrate the USPA platform’s capabilities using tissue-mimicking phantoms.
Session 8: Awards Competition IV
Author(s): Joseph Kuo, Univ of Illinois (United States); Umberto Villa, Washington University in St. Louis (United States); Shuai Na, Peng Hu, California Institute of Technology (United States); Mark A. Anastasio, Univ of Illinois (United States)
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Photoacoustic computed tomography (PACT) is an emerging imaging modality that is actively developed for transcranial neuroimaging in humans. However, elastic-acoustic effects of the skull significantly distort the measured pressure waves and specialized image reconstruction methods are required. These methods are often unfeasible for near-real-time imaging, as they require accurate knowledge of skull’s elastic-acoustic properties and incur significant computational burden. To address these challenges, a two-step reconstruction procedure is proposed in which the output of an approximate but fast reconstruction method is deaberrated using deep learning. Method’s feasibility is demonstrated using 3D image reconstruction studies with simulated and experimental data.
Author(s): Maryam Hatamimoslehabadi, Jessica Gutierrez, Alexander Schill, Yogeshwari Ambekar, Salavat Aglyamov, University of Houston (United States); Xosé Luís Deán-Ben, University of Zurich (Switzerland); Kirill Larin, University of Houston (United States)
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Fetal development is an orchestrated and complex process. Many scenarios can expose the fetus to stress, including preexisting maternal heart diseases, and anemia and cause defective fetal development. Fetal impaired heart function correlates to functional cardiac anomalies in adulthood. It is essential to monitor the progression of the fetus during pregnancy. As the primary model of mammalian development, functional imaging of embryonic mouse models can provide a major contribution to our understanding of mammalian heart development. In vivo characterization of embryonic cardiac function is challenging due to small embryonic size. Here we demonstrate the capability of volumetric optoacoustic imaging as a noninvasive volumetric in studying developmental embryonic cardiac function with high spatial and temporal resolution. In this work, mouse embryos at the gestational days of 14.5 to 17.5 were imaged noninvasively, and the embryonic cardiac function was characterized.
Author(s): Richard Su, TomoWave Laboratories, Inc (United States), Dept. of Biomedical Engineering, University of Houston (United States); Seonyeong Park, Dept. of Bioengineering, University of Illinois at Urbana-Champaign (United States); Umberto Villa, Dept. of Electriucal & Systems Engineering, Washington University in St. Louis (United States); Mark A. Anastasio, Dept. of Bioengineering, University of Illinois at Urbana-Champaign (United States); Alexander A. Oraevsky, TomoWave Labs Inc (United States), Dept. of Biomedical Engineering, University of Houston (United States)
Author(s): Josiah M. Minotto, Haoyang Chen, Mohamed Osman, Sumit Agrawal, Ajay Dangi, Department of Biomedical Engineering, Pennsylvania State University (United States); Huanyu Cheng, Department of Engineering Sciences and Mechanics, Pennsylvania State University (United States)
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While photoacoustic (PA) imaging provides deep tissue vascular oxygenation and molecular information, ultrasound provides underlying anatomical information as well as functional blood flow information. Here, we report a wearable and stretchable USPA patch that is conformable to skin and provides multiparametric deep tissue vascular information. The patch consists of two layers, each with twenty-one copper electrodes (a 4✕5 array layout with a ground), which are conductively connected to a 1-3 composite that exists in between them. Various deep tissue phantom and in vivo experiments demonstrate the USPA patch can provide structural, functional blood flow and oxygen saturation of deep tissue vasculature. The USPA patch has potential applications for monitoring vascular diseases.
Author(s): Zhongtao Cheng, Lihong V. Wang, Caltech (United States)
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A wavefront shaping technique, termed ultrasound-induced field perturbation (UFP) optical focusing, is proposed for focusing light into scattering media. Here, by detecting and time-reversing the differential field of the frequency-unshifted photons when the ultrasound is alternately ON and OFF, we can focus light to the position where the field perturbation occurs inside scattering media. Simulations and experiments are presented to validate the technique. We further develop the UFP optical focusing into double-shot realization and single-shot realization, which is desirable for high-speed wavefront shaping. We hope that it provides an efficient and flexible mechanism for implementing ultrasound-guided wavefront shaping.
Session 9: Laser Ultrasound
Author(s): Linli Shi, Ying Jiang, Lu Lan, Ji-xin Cheng, Chen Yang, Boston University (United States)
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Neuromodulation at high spatial resolution is crucial for advancing understanding of brain circuits and treatment of neurological diseases. Here, a tapered fiber optoacoustic emitter (TFOE) is developed for stimulation of single neurons and subcellular structures. Temporally, a single acoustic pulse of sub-microsecond converted by the TFOE is shown as the shortest acoustic stimuli so far for successful neuron activation. The TFOE enabled integration with highly stable patch clamp recording and unveiled cell-type-specific response of excitatory and inhibitory neurons. Thus, TFOE provides a non-genetic single-cell and sub-cellular modulation platform, which could shed new insights into the mechanism of ultrasound neurostimulation.
Session 10: Novel Systems Including Wavefront Shaping
Author(s): Tianrui Zhao, Sebastien Ourselin, Tom Vercauteren, Wenfeng Xia, King's College London (United Kingdom)
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Photoacoustic (PA) endoscopy has attracted intense research interest recently for the guidance of minimally invasive procedures. In this work, we developed a video-rate ultrathin endo-microscopy imaging system based on a multimode fibre. A deep image prior (DIP) neural network was used to improve the imaging speed and spatial resolution using unsupervised learning. High-fidelity PA images of carbon fibre phantoms and mouse blood cells were acquired at video-rate. We anticipate that with further minimisation of the ultrasound detector, this imaging system could be applied for the guidance of interventional and surgical operations such as fetal surgery and tumour surgery.
Author(s): Xosé Luís Deán-Ben, Univ Zürich (Switzerland)
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Severe distortion of ultrasound waves traversing the skull impedes visualization of cerebral structures in humans. Accurate modelling of ultrasound propagation effects is challenging due to highly heterogeneous acoustic properties of the skull bone. Here we demonstrate that acoustic distortions induced by the skull are preserved for optoacoustic waves generated at neighboring point sources. This memory effect is exploited for building a model describing generation and detection of a signal originating from light-absorbing particle at given position. Model-based inversion is shown to accurately recover the absorption distribution with comparable spatial resolution to that obtained without the presence of the skull.
Author(s): Mohammadreza Amjadian, Seyed Masood Mostafavi, Hong Kong Univ of Science and Technology (Hong Kong, China); Jiangbo Chen, Lidai Wang, City University of Hong Kong (Hong Kong, China); Zhengtang Luo, Hong Kong University of Science and Technology and Technology (Hong Kong, China)
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The aim of this paper is to overcome the acoustic diffraction limit to achieve finer lateral resolution in and out of focus regions. For this purpose, a well-known structured-illumination method is used to increase the acoustic spatial bandwidth to improve the lateral resolution of the system. The illuminated optical beam is shaped by a digital micromirror device (DMD) to form sinusoidal patterns force to shift the object spatial spectrum. The shifted spectrum passes high spatial frequency components through the finite bandwidth of the system. Here, the phase compounding method is modified in comparison with [1] to increase the lateral resolution improvement from 2 to 5 times. To achieve this goal, adding the spatial frequency component of the second order to the fundamental component by considering phase shifts
Author(s): Maxim N. Cherkashin, Thomas J. Allen, Paul C. Beard, Univ College London (United Kingdom); James A. Guggenheim, Univ College London (United Kingdom), University of Birmingham (United Kingdom)
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Photoacoustic (PA) wavefront shaping (WFS) could allow focusing light deep in biological tissue and enable increasing the resolution and penetration depth of techniques including photoacoustic imaging. However, traditional PA excitation lasers are poorly suited to PA-WFS due to their short coherence length (CL). Moreover, the precise CL requirements are unclear. To address this challenge, we developed a PA-WFS system with a long CL and investigated the impact of CL on the focusing efficiency of PA-WFS. This work could inform the design of PA-WFS systems, paving the way to expanding the capabilities of various biomedical optics techniques.
Author(s): Sang Min Park, Soon-Woo Cho, Gyeong Hun Kim, Hansol Jang, Chang-Seok Kim, Pusan National Univ (Korea, Republic of)
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In this work, we present an L-band wavelength-switchable nanosecond pulsed erbium-doped fiber laser using active mode-locking and multiple fiber-cavity length segments with fiber Bragg grating (FBG). It has pulse energy on the order of hundreds of nano-joules and switchable wavelengths of 1580 and 1600 nm. This laser can easily select a wavelength by modulating the mode-locking frequency determined by the cavity length of each wavelength. The pulse repetition rate can be tuned from 250 kHz to1 MHz, according to mode-locking order. To confirm the potential of the proposed laser for use in high-speed functional PAM, we successfully detected a PA signal from the pulse energy of 300 nJ with a PA signal detection system.
Author(s): Çağla Özsoy, Ali Özbek, Xosé Luís Deán-Ben, ETH Zurich (Switzerland), University of Zurich (Switzerland)
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Optoacoustic tomography (OAT) is rapidly becoming an important tool in biological and clinical research. Current OAT system implementations commonly feature bulky and expensive hardware impeding wide-scale adoption. We introduce LightSpeed: a compact, high-speed, low-cost and configurable 3D optoacoustic imager based on an optical-link software-defined acquisition platform and fiber-coupled laser diode illumination. We demonstrate real-time imaging capability of the LightSpeed system by fast handheld scanning of human vasculature. LightSpeed attains image quality comparable to conventional data acquisition electronics at a fraction of hardware costs and significantly faster frame rates. It is then poised to result in new generation compact and high-performance handheld OAT scanners facilitating clinical translation.
Author(s): Sergey A. Ermilov, PhotoSound Technologies Inc (United States); Ibrahim Oraiqat, H. Lee Moffitt Cancer Center and Research Institute (United States); Paul Carson, Wei Zhang, Xueding Wang, University of Michigan (United States); Yan Yan, Maryam Basij, Samuel John, Mohammad Mehrmohammadi, Wayne State University (United States); Hans-Peter Brecht, Vassili Ivanov, PhotoSound Technologies Inc (United States)
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We present technical details, performance characteristics, and examples of biomedical applications utilizing LEGION AMP, a 128-ch 40 dB high-input-impedance signal amplifier that enables third-party multichannel ADCs for accurate, high-sensitivity measurements of small broadband (0.04 to 35 MHz) acoustic signals such as in photoacoustics or X-ray acoustics. Two high-impact biomedical applications are presented illustrating practical utility of the device. In the first application, LEGION AMP was integrated as a part of a clinical-ready ionizing radiation acoustic and ultrasound dual-modality imaging system. In the second application, LEGION AMP significantly improved retrieving the low-intensity PA signals during deep-tissue tracking of magnetically-manipulated microbots.
Author(s): Lyazzat Mukhangaliyeva, Nicholas Pellegrino, Marian Boktor, Layla Khalili, Parsin Haji Reza, PhotomedicineLabs, University of Waterloo (Canada)
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We present a new technique for improving the temporal stability of the Stimulated Raman Scattering (SRS)-based multispectral pulsed source by decreasing the temperature of the SRS medium. This technique reduces temporal fluctuations of the output SRS peaks, generates stable multiwavelength light, improves repeatability and accuracy of functional measurements. This stabilized temperature-regulated SRS-based source is combined with the wide field of view photoacoustic remote sensing microscope utilizing a telecentric scan lens as an imaging objective. In-vivo functional imaging experiments of the chorioallantois membrane of a chicken embryo (CAM) are performed for validation purposes.
Session 11: Advances in Phantoms and Phantom Studies
Author(s): Chenshuo Ma, Daiwei Li, Duke University (United States); Qifa Zhou, University of Southern California (United States); Yu Shrike Zhang, Harvard Medical School (United States); Junjie Yao, Duke University (United States)
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Understanding thrombosis formation is necessary for developing safe and effective treatments. We fabricated sophisticated in vitro models of blood vessels with internal microchannels by using digital light processing-based 3D printing method. Photoacoustic microscopy (PAM) offers a useful platform for imaging 3D-printed vascular structures with different patterns of microchannels. Our results show that PAM can provide clear microchannel structures at depths up to 3.6 mm. We further quantified the blood oxygenation in the 3D-printed vascular models, showing that thrombi had much lower oxygenation than the normal blood. Integration of PAM with 3D printing/bioprinting will enable numerous applications in tissue engineering.
Author(s): Maura Dantuma, Multi-Modality Medical Imaging group, University of Twente (Netherlands); Laurens Alink, Rutger P. Pompe van Meerdervoort, P.A. Imaging b.v. (Netherlands); Ben Cox, Department of medical physics and biomedical engineering, University College London (United Kingdom); Srirang Manohar, Multi-Modality Medical Imaging group, University of Twente (Netherlands)
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From systematic measurements on test objects, a breast mimicking phantom and healthy volunteers we investigated the imaging performance of the PAMMOTH system as a function of settings in the measurement protocol. We varied several measurement parameters, like the number of detection projections or number of averages, to investigate their effect on image quality metrics like the spatial resolution, the signal-to-noise ratio, imaging depth, speed of sound accuracy and the ability to extract blood oxygenation estimations. From these tests, we unravelled an optimized measurement protocol that gives images with the best quality within as short as possible measurement times.
Author(s): David Thompson, Wiendelt Steenbergen, Univ of Twente (Netherlands)
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Timely, accurate assessment of atherosclerotic plaque composition in the carotid arteries to enable prevention of ischaemic stroke is currently an important topic in medical imaging. Photoacoustic imaging, which lacks ionizing radiation and foreign contrast agents, is attracting much interest in the field of non-invasive carotid plaque imaging. We present results of the characterization of our new system, based on a concave ultrasound transducer and optical fibre illumination, as well as multi-wavelength photoacoustic images of a PVCP-based phantom, supplemented with ultrasound plane wave images. The multi-wavelength photoacoustic imaging capability of the probe has potential for eventual carotid plaque imaging and quantification.
Author(s): Jorge Palma-Chavez, University of California San Diego (United States); Keith A. Wear, William C. Vogt, U.S. Food and Drug Administration (United States)
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Phantoms were designed to evaluate boundary buildup effect and object detectability. Tissue-mimicking materials simulating breast fat and parenchyma were prepared through emulsification of silicone oil, ethylene glycol and polyacrylamide hydrogel. Imaging targets were prepared by adding either India ink to the water phase or nigrosin to the oil phase. Phantom and inclusion molds were fabricated using an affordable 3D printer, yielding phantoms containing stepped-cylinder inclusions with 1-8 cm-1 optical absorption coefficients and 1-5 mm diameters. Maximum imaging depth depended on whether target boundary buildup or filled-in features were analyzed, with boundary buildup being more detectable.
Author(s): William C. Vogt, Joshua Pfefer, Keith A. Wear, Brian S. Garra, US Food and Drug Administration (United States)
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Many applications of photoacoustic imaging (PAI) involve transdermal light delivery, and variable epidermal melanin content may be a potential confounding factor causing signal attenuation and imaging artifacts such as clutter. We developed polyvinyl chloride plastisol (PVCP) phantoms including epidermal and dermal layers. Skin phantoms were placed atop a breast-mimicking PVCP phantom to assess image quality. Nigrosin was added to epidermal layers to simulate Fitzpatrick Types I-VI and yielded a melanin-like spectral slope. Image quality testing indicated that higher pigmentation caused stronger clutter and reduced imaging depth. Phantom-based test methods may support evaluation of PAI device sensitivity to skin pigmentation variation.
Author(s): Valeria Grasso, FUJIFILM VisualSonics (Netherlands), Christian-Albrechts-Universität (Germany); Bruno Koller, SCANCO Medical (Switzerland); Jithin Jose, FUJIFILM VisualSonics (Netherlands)
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The assessment of complementary information in multimodality imaging plays a crucial role for the accurate medical diagnosis and improved treatment planning. We developed and fabricated a phantom that mimics the detailed morphology of a mouse, to enable the registration and calibration of multimodality imaging. In particular, the 3D-printed phantom is compatible with CT, MRI, Ultrasound and Photoacoustic. Here we discussed the material selection, model design and 3D printing technique in detail. Besides, the multimodality imaging calibration protocol and multiple applications of the phantom have been included.
Session 12: Contrast Agents, Molecular and Quantitative Imaging
Author(s): Farzin Ghane Golmohamadi, Amna Shah Mehmood, Jan Laufer, Martin-Luther-Univ Halle-Wittenberg (Germany)
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Pump-probe photoacoustic signals of fluorescent proteins (FPs) were measured in vitro as a function of the pump wavelength, the probe wavelength, and time delay. The spectra of the difference signal amplitude were found to reproduce the wavelength dependence of absorption and fluorescence of the FPs. The decay of the difference signal as a function of the time-delay was found to depend on the lifetime of the FPs. The application of this method is evaluated by acquiring tomographic difference images in phantoms. The results suggest that the method provides contrast mechanisms that may be exploited in multiplexed imaging.
Author(s): Hindrik Kruit, Jelle Plomp, Srirang Manohar, Multi-Modality Medical Imaging, University of Twente (Netherlands)
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Percutaneous radiofrequency ablation (RFA) is used to destroy small liver tumors by locally inducing heat. However, there is a high tumor recurrence rate due to insufficient real-time image guidance during the procedure. We studied multi-wavelength photoacoustic imaging for identifying ablated tissue by taking the ratio of the photoacoustic signals at two wavelengths. To realize this, we first simulated the optical penetration in the liver and its influence on the optimal wavelength pair. Finally, the photoacoustic signals of treated and untreated bovine liver tissue were measured between 680 nm to 1100 nm to find candidate wavelength pairs for successful ratio imaging.
Author(s): Yuqi Tang, Junjie Yao, Duke University (United States)
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Photoacoustic computed tomography (PACT) has great potential in mouse brain imaging. Conventional PACT either assumes homogenous optical fluence or uses simplified attenuation model for optical fluence estimation, resulting in inaccurate estimation of absorption coefficient of the chromophore. To optimize the quantitative performance of PACT, we used MCX 3D Monte Carlo simulation to study the optical fluence distribution in a complete mouse brain model, which contains complete anatomy and blood vasculature information. Our results suggest that optical fluence decays five times globally due to strong scattering tissue and fluctuates locally due to additional optical heterogeneity introduced by blood vessels.
Author(s): Brendon S. Restall, Brendyn D. Cikaluk, Nathaniel J. M. Haven, Matthew T. Martell, Roger J. Zemp, Univ of Alberta (Canada)
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Previous photoacoustic remote sensing virtual histology approaches were too slow to use intraoperatively. We present a new scanning methodology with simultaneous galvanometer mirror and constant velocity mechanical scanning to greatly increase image acquisition speed. Human breast and prostate samples are imaged over an area of 4mm x 4mm in 40s with a 0.5μm resolution resolving both cancerous and healthy tissue. Histological detail is clearly visible in our images where tissue organization and subcellular nuclei density can be observed to aid histologists in determining margin status and cancer grading.
Author(s): Carlos Serpa, Univ de Coimbra (Portugal), LaserLeap Technologies (Portugal); Luis G. Arnaut, Univ de Coimbra (Portugal)
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Ultrasound (US) pulses generated after a fast and efficient conversion of energy from a laser pulse into a pressure transient have shown remarkable application versatility. CNT functionalized with siloxane groups produce thin films that generate exceptionally wide bandwidths (170 MHz at −6 dB) and peak pressures >1 MPa when excited by pulsed ps lasers. Vertically-aligned CNT grown to distinct thicknesses and infused with PDMS generate high pressure transients with a peak of 14 MPa and a bandwidth of 180 MHz at -10 dB using a 1064 nm 100 mJ/cm2 laser pulse for excitation. Using the US produced by this nanostructured material we promoted efficient release of FITC-dextran and GFP from a giant unilamellar vesicles core without damaging the phospholipid bilayer. Such tailor made laser US may enable non-invasive targeted release of GUVs and cell transfection over large volumes of tissues in a few minutes.
Author(s): Daniil Nozdriukhin, ETH Zürich (Switzerland), University of Zürich (Switzerland); Alexey Yashchenok, Dmitry Gorin, Skolkovo Institute of Science and Technology (Russian Federation); Daniel Razansky, Xosé Luís Deán-Ben, ETH Zürich (Switzerland), University of Zürich (Switzerland)
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The feasibility of real-time tracking of microparticles in vivo can greatly facilitate the development of new biomedical applications including blood flow characterization or drug delivery. However, existing imaging modalities generally lack the sensitivity to detect the week signals generated by individual particles flowing through vascular networks deep within biological tissues. Also, the temporal resolution is generally insufficient to track the particles in an entire three-dimensional region. Herein, we capitalize on the unique advantages of a state-of-the-art high-frame-rate optoacoustic tomographic imaging system to visualize and track monodisperse core-shell microparticles with a diameter of ~4 μm in the mouse brain vasculature.
Session 13: Machine Learning: Developments and Applications
Author(s): Tri Vu, Mucong Li, Duke University (United States); Yuan Zhou, IBM Research-China (China); Junjie Yao, Duke University (United States)
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When using a linear ultrasound (US) transducer array, photoacoustic computed tomography (PACT) has great flexibility for hand-held clinical applications. However, the linear-array transducer has a limited detection angle and frequency bandwidth, resulting in limited-view and limited-bandwidth artifacts in reconstructed PACT images. Existing solutions often increase system complexity, cost, and/or decrease imaging speed. Here, we propose a deep-learning approach based on Wasserstein generative adversarial network with gradient penalty (WGAN-GP) to reduce the limited-view and limited-bandwidth artifacts. Our results on simulation and experimental data have demonstrated the feasibility of WGAN-GP to substantially improve PACT’s image quality without any hardware modification.
Author(s): Hsuan-Kai Huang, Yang Zhao, Department of Electrical and Computer Engineering, University of Illinois Urbana-Champaign (United States); Yun-Sheng Chen, Department of Electrical and Computer Engineering, University of Illinois Urbana-Champaign (United States), Department of Bioengineering, University of Illinois Urbana-Champaign (United States), Carle Illinois College of Medicine, University of Illinois Urbana-Champaign (United States)
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Photoacoustic imaging is an imaging modality that combines the advantages of rich contrast from optical imaging and deep penetration depth of ultrasound imaging. Nevertheless, the penetration depth of photoacoustic imaging remains limited due to the optical tissue scattering; an analytical compensation is nearly impossible for an imaging target with several tissue types. Here we present an ultrasound-guided deep-learning approach to extend the depth of photoacoustic imaging. Our model can effectively identify the structure and enhance the signal across modality with the structural information acquired from an ultrasound image. With the pre-trained model, we achieved a deep-tissue photoacoustic imaging.
Author(s): Yun Zou, Eghbal Amidi, Hongbo Luo, Quing Zhu, Washington University in St. Louis (United States)
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Quantitative photoacoustic tomography (QPAT) is an important functional extension of PAT for cancer diagnosis. However, reconstruction of optical absorption distribution using QPAT is difficult because it involves an ill posed inverse problem with unknown Grüneisen parameter (Γ), absorption coefficient (μ_a) and optical fluence (ϕ). Here, we proposed a neural network U-net model with prior information to reconstruct absorption coefficient using PAT data. 2000 simulation data and 480 phantom data were generated to train and test the U-net model. Results have shown that the proposed method can accurately estimate target locations and their shapes as well as their optical properties.
Author(s): Tri Vu, Daiwei Li, Duke University (United States); Yu Shrike Zhang, Harvard Medical School (United States); Qifa Zhou, University of Southern California (United States); Roarke Horstmeyer, Junjie Yao, Duke University (United States)
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Limited by the laser’s repetition rate, state-of-the-art high-speed photoacoustic microscopy (PAM) often sacrifices spatial sampling density for increased imaging speed over a large field-of-view. Here, we propose the use of deep image prior (DIP) to improve the image quality of undersampled PAM images. DIP requires neither pre-training nor fully-sampled ground truth, enabling its flexible adaptation on various imaging targets. Our results have demonstrated substantial improvement in PAM images with as few as 1.4 % of fully sampled pixels. Our approach outperforms interpolation methods, is competitive with pre-trained supervised deep-learning methods, and is readily translatable to other high-speed imaging modalities.
Author(s): Anthony DiSpirito, Daiwei Li, Duke University (United States); Jianwen Luo, Tsinghua University (China); Roarke W. Horstmeyer, Junjie Yao, Duke University (United States)
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Traditional raster-scanning photoacoustic microscopy (PAM) systems often have to compromise between spatial resolution and imaging speed. In this study, we propose utilizing deep learning techniques to transcend this resolution-speed tradeoff. We compiled a dataset of high-resolution in vivo mouse brain images, and artificially downsampled them to mimic various high-speed, undersampled scanning paths. We then trained various model architectures to upsample the images, and found a Fully-Dense U-net produced the best results. We demonstrate that our vessel-conscious upsampling method can outperform interpolation and reconstruct PAM images with as few as 2% of the original pixels without substantially sacrificing image quality.
Author(s): Valeria Grasso, FUJIFILM VisualSonics (Netherlands), Christian-Albrechts-Universität (Germany); Jithin Jose, FUJIFILM VisualSonics (Netherlands)
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The volumetric assessment of molecular tissue components is crucial in the diagnosis and treatment of a large number of disease. Here we propose a novel framework that enables the automated assessment of volumetric tissue composition from 3-D spectral photoacoustic imaging. The framework, based on unsupervised ML algorithms, has been tested and validated with tissue mimicking phantoms and in vivo preclinical studies. The initial results show that the proposed image-based framework outperforms the conventional unmixing approaches, with enhanced sensitivity and specificity to differentiate the less prominent absorbers and improved quantification measures in deep tissues.
Session 14: Optical Sensing of Pressure/Displacement
Author(s): Feng He, Edward C. Zhang, James A. Guggenheim, Paul C. Beard, Univ College London (United Kingdom)
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The fibre-optic planoconcave optical microresonator is a new type of highly sensitive broadband optical ultrasound sensor with a near omnidirectional response. We investigate the applicability of this type of sensor to widefield photoacoustic tomography by using it within a cylindrical scanning system and compare the images acquired in phantoms and ex vivo tissues with those obtained with PVDF and PZT receivers and numerical k-wave simulations. This preliminary investigation is expected to inform the design of a preclinical full-view photoacoustic tomography system using fibre-optic plano-concave microresonator sensors.
Author(s): Nathaniel J. M. Haven, Matthew T. Martell, Roger J. Zemp, Univ of Alberta (Canada)
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Photoacoustic remote sensing (PARS) microscopy suffers from slow imaging speeds as a result of so far being an exclusively laser scanning microscopy-based technique. Here we introduce a camera-based PARS approach using a 10 million frames-per-second camera together with oblique 532nm excitation and white-light interrogation. 2mm x 1.2mm images of 20µm diameter gold bonding wires are obtained in fractions of a second albeit with lower resolution. Using these wide-field images, regions-of-interest can be established. Additionally, the observation of supersonic wavefronts suggest the generation of shockwaves. This observation is used to derive an empirical model for the time evolution of PARS signals.
Author(s): Kevan L. Bell, PhotoMedicine Labs, University of Waterloo (Canada), illumiSonics Inc. (Canada); Parsin Haji Reza, PhotoMedicine Labs (Canada)
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A novel photoacoustic remote sensing (PARS) microscopy architecture is presented which replaces the conventional normal-incidence back-reflected operation with independent angled-incidence excitation and collection optical pathways. This new architecture has demonstrated significant detection sensitivity improvements over normal-incidence embodiments, providing order of magnitudes reduction in sample exposure to the detection beam. The efficacy of this new architecture is explored on phantoms, bulk erythrocytes, and in vivo microvasculature. The talk will feature discussions centered around architecture design considerations and explore applications for such a device.
Author(s): Hansol Jang, Chang-Seok Kim, Sang Min Park, Soon-Woo Cho, Jeesu Kim, Pusan National Univ. (Korea, Republic of)
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In this research, we have proposed a non-contact PA sensing system based on external cavity laser feedback interferometric sensor. The output wavelength of the external cavity laser could be changed according to the cavity length. Thus, temporal displacement change due to the PA effect occurs output wavelength change. A delayed Mach-Zehnder interferometer was used as a wavelength to voltage conversion tool. The sensitivity of external cavity laser feedback techniques was compared to the other classical methods of homodyne and low coherence interferometry to figure out the advantages of laser feedback interferometry based on the external cavity laser.
Author(s): Ahiad Refael Levi, Yoav Hazan, Amir Rosenthal, Technion Israel Institute of Technology (Israel)
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Time-domain acousto-optic imaging (AOI) can map the light fluence distribution inside biological tissue with acoustic resolution by insonifying the tissue with acoustic bursts and detecting the resulting light modulation with fast detectors. Due to the small magnitude of the modulated light, sensitive detectors are commonly employed, e.g. photomultiplier tubes, whose low quantum efficiency increases the shot-noise in the signal. In this work, we developed a new AOI approach in which a reference beam is interfered with the modulated light to amplify the signal, enabling the use of low-cost photodiodes, whose high quantum yield led to a 3-fold increase in SNR.
Author(s): Cedric Pieters, imec (Belgium); Wouter Westerveld, TU Delft (Netherlands); Hasan Mahmud-Ul-Hasan, Simone Severi, Roelof Jansen, Veronique Rochus, Xavier Rottenberg, imec (Belgium)
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Photoacoustic tomography defines new challenges for ultrasound detection compared to ultrasonography. To address these challenges, a sensitive, small, scalable, and broadband optomechanical ultrasound sensor (OMUS) has been developed. The OMUS is an on-chip optical ultrasound sensor, using optical interferometric ultrasound detection. It consists of an acoustic membrane on top of an optical ring resonator that modulates the optical ring resonance with high efficiency enabled by an innovative optomechanical waveguide. Raster scanning photoacoustic tomography has been demonstrated with a single-element OMUS. Based on performance and form factor, the OMUS combined with passive optical multiplexing may enable new applications in photoacoustic imaging.
Author(s): David Martin-Sanchez, Edward Z. Zhang, Paul C. Beard, Univ College London (United Kingdom)
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Photoacoustic imaging requires ultrasound transducers able to detect very low-pressure signals. Plano-concave microresonator (PCMR) sensors can reach much higher sensitivities than previously recorded using planar Fabry-Perot sensors. This significantly reduces the minimum detectable pressure, but it also exposes new flaws in the optical system that prevents them from achieving their full potential. This study has explored the limiting factors associated with optimising the optical and acoustic sensitivity of PCMR sensors. Their understanding is fundamental to minimise their effect, which will pave the way for deep tissue clinical applications.
Author(s): Mark Donnachie, Peter W. Tinning, Deepak Uttamchandani, Ralf Bauer, University of Strathclyde (United Kingdom)
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A 3D photoacoustic microscopy (PAM) system is presented and characterized, using optical MEMS and fibre tip transducers as active elements to provide all-optical positioning and read-out for in vitro cellular and sub-cellular resolution imaging. The excitation beam position is controlled using an electrostatically actuated 2-axis MEMS scanner and a tunable lens. This allows for fast 3D scanning without motion induced artefacts caused by stage scanning, and selective imaging of regions of interest. A 20MHz fibre tip transducer is used for acoustic detection, which allows a variety of sample holders to be used including well plates and petri-dishes.
Session 15: Advances in Ultrasound Detection
Author(s): Cheng Fang, Jun Zou, Texas A&M Univ (United States)
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This paper reports dual-modal photoacoustic microscopy (PAM) and ultrasound microscopy (UM) based on an optically-transparent focused PVDF transducer with a high NA of 0.64. The transducer has an acoustic center frequency and bandwidth of 36 MHz and 44 MHz, respectively. With a central transparent window, the excitation laser pulses can directly pass through the transducer to illuminate the target without any blockage. Co-registered 3D and 2D PAM/UM experiments are conducted on a twisted wire in water and chicken breast tissue, and in-vivo on a mouse tail, respectively. Targets at different depths are resolved with high acoustic resolution and contrast.
Author(s): Mohamed Osman, Haoyang Chen, Josiah Minotto, Sumit Agrawal, Sri-Rajasekhar Kothapalli, The Pennsylvania State University (United States)
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The transparent ultrasound transducers (TUT) have recently emerged as an attractive platform for development of multiscale photoacoustic imaging (PAI) systems. TUTs allow easy co-alignment of optical illumination and acoustic detection paths on the tissue surface, averting the complex beam arrangements employed by the current PAI systems that use opaque conventional ultrasound transducers. However, TUTs suffer from narrow bandwidth and low pulse-echo sensitivity due to the lack of suitable transparent acoustic matching and backing layers. To maximize the TUT's potential, we studied glass beads in transparent epoxy as acoustic matching and backing layers. Our experiments demonstrated that TUTs coated with glass beads improve the detection bandwidth and pulse-echo sensitivity while acting as a diffuser to achieve uniform light distribution on the tissue surface.
Author(s): Cheng Fang, Jun Zou, Texas A&M Univ (United States)
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This paper reports a new optically-transparent 1D PVDF (polyvinylidene fluoride) transducer array for photoacoustic tomography (PAT). With a transparent window in each of the 16 elements, optical excitation and ultrasound detection are automatically aligned, which helps to improve the illumination condition and PA excitation efficiency. Its imaging performance, including sensitivity, contrast, lateral resolution, and penetration depth is characterized with optical phantoms. Preliminary ex-vivo imaging on chicken breast tissues is conducted to demonstrate imaging capability on real biological samples. Results show the optically-transparent PVDF transducer array could provide a new solution for the miniaturization and clinical translation of handheld PAT systems.
Author(s): Mahyar Ghavami, Afshin Kashani Ilkhechi, Roger Zemp, University of Alberta (Canada)
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In this work, we report the fabrication of a highly sensitive transparent CMUT array for through-illumination photoacoustic imaging, which can provide a higher signal-to-noise ratio compared to conventional oblique illumination. Using the sacrificial release technique, we are able to achieve small gaps in transparent CMUT cells to increase the sensitivity of the transducer in receive mode, which enables detecting photoacoustic signals by the transducer even with low laser powers.
Author(s): Amir Gholampour, Hans-Martin Schwab, Min Wu, Richard Lopata, Eindhoven University of Technology (Netherlands)
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Photoacoustic imaging (PAI) has a great potential to assess vulnerable plaques in the carotid artery. However, in vivo, PAI suffers from low angular coverage, limited field of view (FOV), and lateral resolution especially when imaging a few centimeters deep in the tissue. To improve these shortcomings, here, we propose to image with multiple capacitive micromachined ultrasound transducers on a flexible substrate with orientation sensors to improve the image quality independent of the patient anatomy. We tested the multi-perspective PAI on a phantom and the experimental results demonstrate improvement in FOV, angular coverage, and resolution, strongly increasing the diagnostic capability of the PAI system.
Author(s): Mahyar Ghavami, Afshin Kashani Ilkhechi, Roger Zemp, University of Alberta (Canada)
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In this work, a flexible transparent CMUT array is fabricated for through-illumination photoacoustic applications in which shape conformality is required. The array is composed of glass pieces with transparent structural layers on them, which are connected to each other via PDMS, making the array flexible. Unlike the previous flexible devices in the literature, the array is very robust to bending. The photoacoustic image of a wire target was successfully reconstructed using the fabricated flexible transparent CMUT array. The fabricated device offers promise for future photoacoustic tomography systems with through-array illumination.
Session 16: Advances in Endoscopy and Microscopy
Author(s): Shang Gao, Haichong K. Zhang, Worcester Polytechnic Institute (United States)
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Laparoscopic surgery is commonly used in abdominal creating minimal trauma to the patient. With the current standard videoscope, visualizing vessels under the tissue is challenging. A miniaturized photoacoustic (PA) laparoscopic should increase the maneuverability inside the abdominal for better vascular visualization of the operational region. In this work, a PA laparoscopic system imaging with only two diffusing side-illumination fibers was proposed, which miniaturized the light delivering mechanism while maintaining sufficient illumination comparing to use angled-tip side-illumination fibers. The phantom evaluation result demonstrated the feasibility of delivering sufficient energy with diffusing fiber to miniaturize the dimension of PA laparoscopic device.
Author(s): Linyu Ni, Yunhao Zhu, Laura Johnson, Jonathan Rubin, Peter Higgins, Xueding Wang, Univ of Michigan (United States); Guan Xu, University of Michigan (United States)
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Stiffness is a biomarker to distinguish intestinal inflammation and fibrosis in Crohn’s disease. This study investigated the performance of an endoscopic photoacoustic (PA)-ultrasound (US) catheter probe in quantifying intestinal stiffness in rabbits in vivo. The probe integrated a miniaturized US array and a side-firing fiber optic inside a medical balloon catheter. During the balloon dilation, the ratios between the intestinal wall deformation and PA signal change were quantified. The strain-PA ratios measured in vivo demonstrated a correlation of 0.8 (n=55, p=0.01) with the Young’s moduli of the assessed intestinal segments determined by microelastometry ex vivo.
Author(s): Li Li, Nicolas Graff, Guillermo J. Tearney, Massachusetts General Hospital (United States)
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Real-time assessment of central hemodynamics could advance cardiovascular, trauma and intensive care. We have developed a Transesophageal Echo-oximeter (TEO) that incorporates photoacoustic oximetry with transesophageal echocardiography to provide comprehensive hemodynamic assessment. Here, we report our recent development of a portable battery-powered TEO device suitable for point-of-care applications, and a miniaturized probe that can utilized transnasally in unsedated patients and operated by minimally trained caregivers. Experimental results from tissue phantoms using a 3D-printed human nasogastric model will be presented. Future efforts will focus on improving system robustness and testing in large animals and patients.
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This work involves the development of a novel endoscope based on Photoacoustic Remote Sensing (PARS), for label-free in vivo imaging of microvasculature. The PARS endoscopy is realized by raster-scanning the proximal end of a coherent, image-guide fiber bundle containing 30,000 cores arranged within a 600-µm diameter image-circle. A graded-index (GRIN) distal-end objective lens is used to focus and collect the reflected probe beam. Based on preliminary results, the endoscope is measured to have a resolution of less than 3-µm. The developed PARS endoscope is characterized using phantoms and validated for in vivo application using a live chicken embryo model.
Author(s): Gyeong Hun Kim, Soon-Woo Cho, Sang Min Park, Jeesu Kim, Chang-Seok Kim, Pusan National University (Korea, Republic of)
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We proposed we proposed a novel wavelength-tunable picosecond burst-mode fiber laser based on the dispersive active mode-locking technique for high-speed multispectral photoacoustic microscopy. Using this configuration, rapidly wavelength tunning can be implemented in the broad region of 1030~1110 nm by changing the modulation frequency. After the output of the seed laser, a semiconductor optical amplifier (SOA) driven by the external programmable signal is employed for both optical amplification and pulse modulation. By providing an adjustable shaped burst of the ps-pulses train from the seed laser, this burst envelop can successfully act like a ns-pulsed laser required for PAM. We expect this new laser source to be widely used in real-time multispectral PAM applications.
Author(s): Brendyn D. Cikaluk, Matthew T. Martell, Nathaniel JM Haven, Brendon S. Restall, Roger J. Zemp, University of Alberta (Canada)
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An estimated 20-40% of patients who undergo breast-conserving surgery require repeat operations due to the length of time required post-surgery to analyze the resected sample. Recently, a novel non-contact microscopy technique known as ultraviolet photoacoustic remote sensing (UV-PARS) has been developed, which can produce virtual hematoxylin and eosin (H&E) stained images. By using a voice-coil scanning stage in conjunction with an on-demand pulsed laser, we demonstrate 1cm x 1cm gross UV-PARS virtual H&E scans in approximately 50 seconds, along with full-resolution 1cm x 1cm scans in approximately 8 minutes. With widefield high-speed scanning, UV-PARS shows promise for future translation to clinical application.
Author(s): Maomao Chen, Duke University (United States); Xiaoyu Duan, Texas A&M University (United States); Bangxin Lan, Xiaoyi Zhu, Wei Yang, Ulrike Hoffmann, Duke University (United States); Jun Zou, Texas A&M University (United States); Junjie Yao, Duke University (United States)
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Optical-resolution photoacoustic microscopy (OR-PAM) can image biological tissues at micrometer level resolution. However, the imaging speed of traditional OR-PAM is often too slow for capturing dynamic information. In this work, we demonstrate a high-speed OR-PAM system using a water-immersible two-axis torsion-bending scanner, in which the fast axis employs the torsion scanning while the slow axis works at the bending mode. The system has achieved a cross-sectional frame rate of 400 Hz, and a volumetric imaging speed of 1 Hz over a field of view of 1.5 × 2.5 mm2. We have demonstrated high-speed OR-PAM of fast hemodynamic changes in vivo.
Session 17: Signal and Image Processing
Author(s): Niklas Holzwarth, German Cancer Research Center (Germany); Melanie Schellenberg, German Cancer Research Center (Germany), Faculty of Mathematics and Computer Science, Heidelberg University (Germany); Philipp Biegger, German Cancer Research Center (Germany); Kris K. Dreher, German Cancer Research Center (Germany), Faculty of Physics and Astronomy, Heidelberg University (Germany); Jan-Hinrich Nölke, Alexander Seitel, Heinz-Peter Schlemmer, German Cancer Research Center (Germany); Lena Maier-Hein, German Cancer Research Center (Germany), Medical Faculty, Heidelberg University (Germany), Faculty of Physics and Astronomy, Heidelberg University, Heidelberg, (Germany)
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Photoacoustic tomography (PAT) enables imaging of functional tissue properties but lacks context information available from magnetic resonance imaging (MRI) or computed tomography (CT). Multimodal image fusion could alleviate this problem but is an unsolved challenge to date. We present the next generation of a previously presented optical pattern (Tattoo) that enables fusion of diagnostic images with PAT slices via point-based registration introducing additional reattachable markers to the pattern. Phantom experiments indicate a target registration error smaller than 3 mm. We conclude that Tattoo image fusion could become a valuable tool for multimodal image fusion in the context of clinical PAT.
Author(s): Ali Özbek, Xosé Luís Deán-Ben, ETH Zurich (Switzerland), University of Zurich (Switzerland)
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State-of-the-art optoacoustic tomography (OAT) systems can achieve 3D frame rates in the kilohertz range. This creates a demand for faster data processing methods and more efficient means of data storage, especially for lengthy time-lapse acquisitions. Herein, we developed an adaptive OAT data compression method coupled with an efficient reconstruction algorithm capable of reconstructing images directly from the compressed data. Adaptive compression was able to achieve compression ratios between 20 and 1000. Direct reconstructions from the compressed data outperformed parallel back-projection algorithms in terms of computational time to provide real-time volumetric reconstruction on a CPU.
Author(s): Marian Boktor, Nicholas Pellegrino, Paul Fieguth, Parsin Haji Reza, University of Waterloo (Canada)
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Photoacoustic Remote Sensing (PARS®) is a non-contact, label-free imaging modality that provides optical absorption contrast in biological tissues. Images are formed by raster-scanning over a target. A time-domain signal is collected at each point, representing initial pressure-induced via the photoacoustic effect. Conventionally, only the amplitude of the time-domain signals is considered to estimate pixel values, disregarding the rich temporal information present in the signals. For instance, the signal shape carries information, which may be related to specific biological structures. In this work, clustering based on signal shape is explored, followed by feature extraction, enabling the virtual labeling of PARS images.
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Photoacoustic tomography (PAT) provides bio-imaging with high optical absorption contrast, high acoustic resolution, and deep penetration. Previously, we proposed a frequency domain delay-multiply-and-sum (F-DMAS) signal reconstruction method to axial resolution of optical resolution photoacoustic microscopy. Here we extend the F-DMAS to 2D F-DMAS (2D F-DMAS) and apply 2D F-DMAS to PAT images to improve spatial resolution and contrast simultaneously. Simulations of PAT are used to verify the efficacy of the proposed 2D F-DMAS. The improvement achieved with the proposed method will be further verified by phantom experiments and in vivo imaging.
Author(s): Amir Gholampour, Hans-Martin Schwab, Min Wu, Richard Lopata, Eindhoven University of Technology (Netherlands)
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The assessment of tissue composition using photoacoustic imaging (PAI) is a promising approach. However, the signal-to-noise ratio in PAI systems are quite low in comparison to ultrasound imaging’s especially at few centimeters depth. Multi-perspective photoacoustic imaging (MP-PAI) using multiple capacitive micromachined ultrasound transducers (CMUTs) on a flexible substrate provide a cost-efficient way to improve field of view (FOV), resolution, and angular coverage. In this work, an encoding scheme based on Hadamard codes is proposed to improve the SNR in MP-PAI. The concept is validated in an experiment using a carotid plaque tissue sample demonstrating the increase in SNR imaging with three CMUTs.
Conference attendees are invited to attend the BiOS poster session. Come view the posters, enjoy light refreshments, ask questions, and network with colleagues in your field. :: :: View poster presentation guidelines and set-up instructions at: :: [{}+{}]
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One of the primary challenges in breast cancer diagnosis and treatment is intratumor heterogeneity (ITH), i.e., the co-existence of different genetically and epigenetically distinct malignant cells within the same tumor. Identification of ITH is critical for designing better treatments and hence to increase patient survival rates. Here, we report a non-invasive approach that integrates photoacoustic computed tomography (PACT) with multitargeted and multiplexed patchy polymeric photoacoustic contrast agents (MTMPPPCAs). The target specificity of MTMPPPCAs to distinguish estrogen and progesterone receptor-positive in breast tumors was demonstrated through both fluorescence and photoacoustic measurements and validated by tissue pathology analysis.
Author(s): Caitlin Smith, Jami Shepherd, Department of Physics, University of Auckland (New Zealand), Dodd-Walls Centre for Photonic and Quantum Technologies (New Zealand); Guillaume Renaud, Department of Imaging Physics, Delft University of Technology (Netherlands), Sorbonne Université, CNRS UMR 7371, INSERM UMR S 1146, Laboratoire d'Imagerie Biomédicale (France); Kasper van Wijk, Department of Physics (New Zealand), Dodd-Walls Centre for Photonic and Quantum Technologies (New Zealand)
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Photoacoustic imaging utilises the high optical contrast between hemoglobin and soft tissue to generate images of blood vessels. By determining each pixel’s average phase shift across a series of images, the movement of the absorbers can be determined using a technique called Photoacoustic Velocimetry. This method solves the photoacoustic Doppler equation using a least-squares approach to determine the magnitude and direction of flow at each pixel without prior knowledge of the angle of flow. This novel technique is demonstrated using data obtained from simulations and bench-top experiments.
Author(s): Praveenbalaji Rajendran, Manojit Pramanik, Nanyang Technological Univ (Singapore)
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Pulsed laser diodes (PLD) are preferred as excitation sources in photoacoustic tomography due to their low cost, compact size, and high pulse repetition rate. When PLD is used in conjunction with multiple single-element ultrasound transducers (SUT), the imaging speed can be improved. However, during PAT image reconstruction, the exact radius of each SUT is required for accurate reconstruction. Herein, we propose a novel deep learning approach to alleviate the need for radius calibration. We developed a convolutional neural network (fully dense U-Net) with a convolutional long short-term memory (LSTM) block as the bridge to reconstruct the PAT images. In vivo imaging was used to verify the performance of the network. Our results and analysis demonstrate that the proposed network eliminates the need for radius calibration without sacrificing the reconstructed PAT image quality.
Author(s): Sinyoung Park, Chulhong Kim, Pohang University of Science and Technology (Korea, Republic of); Jeesu Kim, Pusan National University (Korea, Republic of)
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We have successfully achieved simultaneous photoacoustic (PA) and ultrasound (US) whole-body imaging of small animals in vivo through a dual-modal PAUS imaging system. PA and US imaging provide complemental information respectively and US imaging is excellent at detecting the location of animal skin layers. The quality of the PA images has been improved by removing the signal from the corresponding skin layer. Based on the skin layer the depth of each PA signal to provide depth-resolved PA images was calculated. After in vivo imaging, the location of each organ was validated by comparing invasively acquired mouse photographs with PA images.
Author(s): Tianrui Zhao, Sebastien Ourselin, Tom Vercauteren, Wenfeng Xia, King's College London (United Kingdom)
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Photoacoustic endoscopy (PAE) promises to provide diagnosis information and treatment guidance in several clinical contexts. In this work, we developed a transparent ultrasound sensor based on a polyvinylidene fluoride thin film with indium tin oxide as electrodes. The sensor had a diameter of 2 mm, an optical transmission rate of ~ 65% to 75% in the wavelength range of 450 to 700 nm, a centre frequency of 15 MHz and a -6 dB bandwidth of 20 MHz. In the future, a forward-reviewing PAE probe will be developed based on this transparent sensor to guide minimally invasive procedures.
Author(s): Eduardo A. Gonzalez, Muyinatu A. Lediju Bell, Johns Hopkins Univ (United States)
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Our dual wavelength atlas approach to spectral unmixing has the potential to differentiate two chromophores using only two optical wavelengths. This work investigates the optimization of our method by varying six parameters. An iterative process was used to determine the optimal set of parameters by changing each parameter one at a time and finding which value returned the highest combination of sensitivity and specificity. Once the optimal set of parameters were applied, our novel dual-wavelength atlas method resulted in 10% higher balanced accuracy. These results are promising for photoacoustic-guided surgery.
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A compact linear array of piezoelectric micromachined ultrasound transducers (PMUTs) based on thin film lead zirconate titanate (PZT) is designed, fabricated, and integrated to a microfluidic channel. Such a unification is known as the PMUT-Microfluidic-Integration (PMI) and is based on establishing bonding between PDMS based microchannel to the thin film PZT. This is the first successful attempt to integrate PMUTs to microfluidic channels and is itself novel in approach. The PMI hence created will be used to photo-acoustically determine the concentration levels of glucose dissolved in phosphate-buffered saline by illuminating the microfluidic channel with nanosecond laser pulses.
Author(s): Van Phuc Nguyen, Yanxiu Li, Thomas Qian, Univ of Michigan-Kellogg Eye Ctr. (United States)
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Corneal neovascularization (CNV) is a serious sight-threatening complication causing vision loss and blindness worldwide. To treat CNV, laser photocoagulation, photodynamic therapy with photosensitizer-verteporfin, and anti-VEGF bevacizumab (BEV) are often utilized, but these treatments can damage adjacent, healthy corneal tissue, blur vision, and cause eye discomfort with limited efficacy. To improve the treatment efficiency and reduce these side-effects, the current study describes a novel CNV treatment using miniature biodegradable silicone nanoneedles (SiNNs) fabricated on a water-soluble contact lens. These SiNNs were successfully encapsulated with BEV (BEV@SiNNs) and used as drug carriers to delivery long-term, sustained drug delivery. The potential treatment effects of BEV@SiNNs were evaluated on rabbit corneal neovascularization models. The contact lens dissolved within one minute. CNV were gradually reduced and disappeared after 14 days post-treatment in vivo.
Author(s): Changho Lee, Department of Nuclear Medicine & Artificial Intelligence Convergence, Chonnam National University Medical School & Hwasun Hospital, Hwasun, Jeollanamdo 58128, Korea (Korea, Republic of); Thanh Dat Le, Chonnam National Univ (Korea, Republic of)
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Optical resolution-photoacoustic microscopy (OR-PAM) is a microscopic system to provide optical absorption contrast in biological tissue. Currently, high-speed OR-PAM scanning faced the limitation of the millimeter-scale field of view (FOV). Without hardware updates, mosaic processing was used to generate a wide FOV PAM image by merging narrow-ranged PAM images. Using feature generation algorithms, feature points were selected by binary decision and were merged by homography estimation. In this study, the diverse feature generation algorithms were applied and compared to estimate their performances for mosaic PAM imaging. Based on the results, mosaic processing implemented with a wide-field OR-PAM system was applied.
Author(s): Thanh Dat Le, Chonnam National Univ (Korea, Republic of); Changho Lee, Department of Nuclear Medicine & artificial intelligence Coverage, Chonnam National University Medical School, 264, Seoyang-ro, Hwasun-eup, Hwasun-gun, Jeollanam-do 58128, Korea (Korea, Republic of)
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Photoacoustic microscopy (PAM) is a multiscale microscopy technique with optical absorption contrast. With tight acoustic focusing, acoustic-resolution (AR-PAM) reaches the depth of several centimeters in biological tissue, but the lateral resolution is relatively poorer than optical-resolution PAM (OR-PAM). We proposed using CycleGAN to generate new OR-PAM images from the original AR-PAM images. We prepared two AR & OR-PAM datasets from leaf phantom and mouse-ear samples. After completing the CycleGAN process, we estimated the quality comparison between the original AR-PAM and the generated OR-PAM images. Finally, the results showed the ability to obtain high spatial resolution PAM images without hardware updates.
Author(s): Moongyu Han, Byullee Park, Chulhong Kim, Pohang Univ of Science and Technology (Korea, Republic of)
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Excessive bleaching can cause changes in the amino acid composition as well as the surface structure of the hair. Thus, proper hair bleaching and quantification is important to achieve cosmetic purposes while maintaining the healthy properties of the hair. Here, we propose a novel method to quantify the degree of hair bleaching at the nanoscale resolution using a photoactivated atomic force microscopy (pAFM). We demonstrated that acquiring and quantifying pAFM images of hair according to bleaching time can help determine the appropriate bleaching time. We believe that this result will help to prevent unwanted hair damage due to bleaching.
Author(s): Jeongwoo Park, Byullee Park, Chulhong Kim, Pohang Univ of Science and Technology (Korea, Republic of)
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We present high-resolution and high-SNR in vivo vascular imaging of the mouse eye, brain, and ear with photoacoustic microscopy (PAM) integrated with a transparent ultrasound transducer. We observed microvessels in a chemically damaged mouse eye. Particularly, the performance of PAM as a comprehensive eye disease diagnosis tool was demonstrated by observing not only corneal neovascularization, but also iris blood vessels and hemorrhages in a cloudy state of the corneal. Second, we delineated in vivo mouse brain vascular imaging at high resolution with a depth encoding. Third, we monitored the ears of tumor-bearing mice to observe for angiogenesis over time.
Author(s): Donghyeon Oh, Seunghyun Lee, Chulhong Kim, Pohang Univ of Science and Technology (Korea, Republic of)
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In molecular photoacoustic imaging, the administration of an external photoacoustic contrast agent increases the photoacoustic yield and clarifies pathophysiological observation over the lesion site. Recognizing the necessity of a cyanine-based dye that complements the optical properties of ready-approved indocyanine green, we proceeded with molecular photoacoustic imaging in vitro and in vivo using cypate with a high absorption rate and photothermal conversion yield in the near-infrared I region. In addition, the particles are functionalized with tumor-avid peptide to facilitate receptor-based active delivery.
Author(s): Chenshuo Ma, Duke University (United States); Huijuan Zhang, University at Buffalo (United States); Yuqi Tang, Duke University (United States); Jun Xia, Jonathan F. Lovell, University at Buffalo (United States); Junjie Yao, Duke University (United States)
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The second-near-infrared (NIR-II) window has been increasingly explored for photoacoustic (PA) imaging. A strong NIR-II absorbing contrast dye surfactant formulated cyanine dye BIBDAH has been developed and the deep PA imaging confirmed the NIR-II dye was rapidly circulated by intravenous injection, accumulated in the liver after 24 hours and then metabolized after 48 hours. By contrast, the dye can sustain for days with intraperitoneal (IP) injection. This study shows that the IP injection can be useful for prolonged PA imaging with stable intravascular concentration. IV injection is useful for strong signal enhancement in a short time window post-injection.
Author(s): Patricia Vieten, Kris K. Dreher, German Cancer Research Center (Germany), Faculty of Physics and Astronomy, Heidelberg University (Germany); Niklas Holzwarth, German Cancer Research Center (Germany); Melanie Schellenberg, German Cancer Research Center (Germany), Faculty of Mathematics and Computer Science, University Heidelberg (Germany); Jan-Hinrich Nölke, Alexander Seitel, German Cancer Research Center (Germany); Janek Gröhl, Cancer Research UK Cambridge Institute, University of Cambridge (United Kingdom); Lena Maier-Hein, German Cancer Research Center (Germany), Faculty of Mathematics and Computer Science, Heidelberg University (Germany), Medical Faculty, Heidelberg University (Germany)
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Photoacoustic imaging (PAI), when combined with ultrasound (US), offers spectacular opportunities for the detection, staging and therapy of various diseases. Towards clinical translation of PAI, we investigate if our proposed deep learning-based approach can exploit multispectral photoacoustic image data for semantic segmentation of clinically relevant structures, such as lymph nodes and glands, thus addressing the demand for an interpretable visualization of images acquired with a hybrid PAI/US system in the specific context of head and neck imaging. According to our feasibility study, the presented approach allows for semantic segmentation of a variety of clinically relevant tissue structures.
Author(s): Jakub Budisky, Jiri Jaros, Brno University of Technology (Czech Republic)
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We present a GPU-accelerated full-wave solver suitable for fast reconstruction of photoacoustic (PA) images. This solver features a network interface that can be connected to the PA scanner for in-situ processing of incoming ultrasound data. We will show that the first image, composed of 384x384x256 voxels at 0.8mm resolution, can be produced within 73 seconds. Moreover, since many scanners scan the sample from multiple angles or rotation positions, the quality of images can be progressively improved every 73 seconds after new PA data is available.
Author(s): Yuqi Tang, Duke University (United States); Xiaoning Jiang, North Carolina State University (United States); Junjie Yao, Duke University (United States)
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Optimal treatment of venous thromboembolism is determined by the age, size, and composition of the clots, which can be readily estimated using photoacoustic computed tomography (PACT). With intravascular light delivery and PACT’s inherent sensitivity toward hemoglobin, multispectral PACT can accurately estimate clot composition and oxygenation level beyond ten-centimeter of tissue, which may reflect the clot age. Our results also suggest that retracted and unretracted clots have different acoustic frequency spectrum. Clots with higher fibrin concentration have larger percentage of high frequency component. The PACT characterization results are consistent with the tension tests and histology results.
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A non-contact, dual-modal imaging apparatus is introduced which will be used to obtain the Metabolic Rate of Oxygen (mRO2) in the live murine eye, based on the blood flow rate and blood Oxygen Saturation (sO2) measurements. The apparatus is comprised of both Photoacoustic Remote Sensing (PARS) and Swept-Source Optical Coherence Tomography (SS-OCT) systems, operating synchronously. A phantom model will be imaged using the proposed system to validate the accuracy of the blood flow and sO2 measurements. To the best of our knowledge, this work would report for the first time, non-contact, in-vivo measurement of the mRO2 in the ophthalmic tissues.
Author(s): Alkris Warren, Parsin Haji Reza, Univ of Waterloo (Canada)
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All-optical, non-contact, real-time temperature feedback is highly desirable for many medical and non-medical applications. Photoacoustic Remote Sensing (PARS) is an all-optical, non-contact photoacoustic (PA)-based modality that offers several potential advantages for real-time temperature monitoring. Remote sensing opens opportunities for biological temperature monitoring where contact is undesirable or unfeasible altogether. The all-optical mechanism can be leveraged to improve design flexibility and miniaturization, allowing for wider applications in clinical and non-clinical settings. The goal of this study is to experimentally observe and quantify the relationship between the PARS mechanism and temperature, and leverage it to acquire real-time temperature feedback in various media.
Author(s): Wangyu Kim, Wonseok Choi, Changyeop Lee, Joongho Ahn, Chulhong Kim, Pohang Univ of Science and Technology (Korea, Republic of)
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Recently, 3D photoacoustic (PA) and ultrasound (US) technologies have been developed in various forms. There are roughly two main streams to obtain a 3D image; an 1D array US transducer with motorized scanner and a 2D matrix array US transducer. The former has limitations such as longer time to obtain a single 3D image, bulky design with the scanner that degrades portability, and anisotropic resolution. In contrast, the latter acquires and generates a 3D image at once, which enables real-time imaging, compact design, and isotropic resolution. In this study, we demonstrate dual-modal PA and US imaging using a 2D matrix array transducer scanner. The resolution was measured through a phantom experiment, and the methylene blue signal was verified through a rat SLN experiment.
Author(s): Wenhan Zheng, Jun Xia, Univ at Buffalo (United States)
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Slit-based photoacoustic tomography improves the elevation resolution of a linear array through acoustic diffraction. In this study, we developed a third-generation slit-based photoacoustic tomography system with co-planar light illumination and acoustic detection. This design was achieved through a double-mirror illumination scheme and an optically transparent slit. Compared to the previous design, which used side-illumination and a metal slit, the new system provides greater imaging depth and improved compactness. Vasculature from deeper regions can be revealed clearly, making the system valuable for translational imaging applications.
Author(s): Mucong Li, Chenshuo Ma, Junjie Yao, Duke University (United States)
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Preclinical animal study is essential for the research of the presence and progression of biological activities and disease models. Ultrasound imaging is one of the major modalities to perform structural imaging with its high safety and cost-effectiveness. Enabled by microbubbles, acoustic angiography can provide quantitative imaging of the blood perfusion. Photoacoustic imaging allows molecular imaging by detecting light-induced acoustic signals. We seamlessly integrated the three modalities, US, AA, and PA, into a single imaging platform for small animal studies. We performed various biomedical applications to demonstrate the complementary information the tri-modality system can provide.
Author(s): Kaustav Roy, Indian Institute Of Science (India)
Author(s): David Thompson, Frans Segerink, Srirang Manohar, Univ of Twente (Netherlands)
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In the application of ultrasound imaging for medical purposes as well as for non-destructive testing, the search is ongoing for more broadband tunability in a simple, affordable platform. We have developed PDMS-based laser-induced ultrasound transmitters, illuminated by vertical-cavity surface-emitting laser diodes driven by a custom-built, flexible pulser. A broad tuning range between 0.5 and 5.5 MHz can be achieved by illuminating various transmitters, containing different concentrations of optically absorbing cabon black, with optical pulses with durations in excess of the stress confinement. Use of multiple excitation wavelengths and a blend of absorbing materials could result in a single, multi-purpose transmitter.
Author(s): Rianne Bulthuis, Maura M. Dantuma, University of Twente (Netherlands); Felix F. Lucka, University College London (United Kingdom), Centrum Wiskunde & Informatica (Netherlands); Ben B. Cox, University College London (United Kingdom); Srirang S. Manohar, University of Twente (Netherlands)
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We discuss insights from a set of preliminary studies conducted on healthy volunteers using the hybrid photoacoustic-ultrasound breast tomography PAMMOTH system. We studied the effect of different skin types on the reconstructed images. Further, we investigated the influence of choice of sizes of the breast immobilizing cups on imaging of the whole breast. Further, an aid to improved breast positioning was developed, and improvements by its use on repeat-imaging were assessed. We also looked at the relation between body mass index and breast volume inclusion into the imaging field of view.
Author(s): Francis Kalloor Joseph, Wiendelt Steenbergen, Univ of Twente (Netherlands)
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LED-based photoacoustic imaging has great translational potential but has limited imaging depth. We aim to improve the imaging depth of LED-based photoacoustic imaging by optimizing the geometry and number of LED elements. We present Monte Carlo-based light propagation simulations to find the optimal angle of illumination using an array of 576 elements. Simulation studies in a muscle mimicking medium show that an imaging depth of 29 mm can be achieved using the proposed configuration. Experimental studies using chicken breast tissue show an imaging depth of 27 mm. Results highlight the potential of optimizing illumination in LED-based photoacoustic imaging to improve the imaging depth.
Author(s): Lukas Bugyi, Wolfgang Drexler, Mengyang Liu, Medizinische Univ. Wien (Austria)
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We present a novel cost-effective and compact laser source in the application of photoacoustic microscopy (PAM). This source is a Q-switched microchip laser with saturable semiconductor mirrors (SESAM). The source presented in this work has a wavelength of 532nm and a pulse width of 100ps at 100kHz repetition rate. The linewidth of the output pulse is measured to be 0.01nm and the jitter was below 0,114μsec while relative pulse to pulse energy variation was below 9,11%. The laser is compact at 15,03cm(L) by 6,56cm(H) by 9,22cm(W). The scanner utilizes the voice-coil scanning scheme with a focused transducer. We are targeting a lateral resolution of 4μm and an axial resolution of 40μm with signal to noise ratio of 12,105dB. To demonstrate this laser's applicability, phantom and zebrafish embryos are imaged.
Author(s): Kaustav Roy, Indian Institute Of Science Bengaluru (India); Souradip Paul, IISER (India)
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Photoacoustic imaging is a composite imaging modality that offers rich optical contrast and scalable acoustic resolution in higher imaging depth. Many biomedical applications have been investigated to show its unique capability in clinical and preclinical imaging, such as breast cancer imaging, lymph node mapping, animal whole body imaging, etc. As in photoacoustic imaging, the detection part is fully contributed by the ultrasound. The central frequency of the ultrasound transducer has a great role in reconstructed image quality evaluation. In this study, we proposed the performance of a real time-based image reconstruction algorithm under various central frequency and transducer bandwidth.
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Photoacoustic Imaging (PAI) is an emerging medical imaging technology that uses optical excitation and acoustic detection to give high contrast and high resolution. Since in PAI, ultrasound waves are used to detect the signal, a large number of the beamforming algorithms used in Ultrasound (US) imaging can be applied to PAI. Delay and Sum (DAS) is the most commonly used beamforming algorithm in both US imaging and PAI because of its simple implementation and real-time capability. However, using a DAS beamformer results in low resolution and high sidelobes. To address these issues, the phase coherence weighing technique was introduced in US imaging.
Author(s): Anjali Thomas, IISER Thiruvananthapuram (India)
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Enhancement of photoacoustic (PA) signal from contrast agents is a two-stage enhancement mechanism in which the introduction of a contrast agent itself enhances the PA signal from the target. In this work, we are reporting our enhancement study for indocyanine green (ICG), which is a commonly using contrast agent in PAI. In our study, we employed a continuous wave (CW) laser to illuminate the dye before imaging so as to raise the temperature of the dye before imaging. PA image obtained without and with CW laser illumination is compared and the enhancement is calculated for various parameters. It is observed that the PA signal is increased significantly due to CW laser illuminations. In addition to that, the SNR of the images obtained with CW laser is also improved. Conclusively, this is a promising technique to improve the signal strength and SNR of PA images using contrast agents and ICG in particular.
Author(s): Souradip Paul, Anjali Thomas, IISER-TVM (India); Mithun Kuniyil Ajith Singh, CYBERDYNE, INC. (Netherlands); MAYANGLAMBAM SUHESHKUMAR SINGH, IISER-TVM (India)
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LED-based photoacoustic imaging systems are portable and affordable when compared to the conventional laser-based systems. However, the LED-based imaging suffers low SNR and consequently offers limited imaging depth. To address these issues, a new adaptive weighting factor named signal-mean-to-modified-standard-deviation-factor (SMMSF) is introduced. Our novel beamforming approach is targeted at improving resolution, SNR, and imaging depth in photoacoustic imaging. Our weighted technique also leads to narrow main lobes in beamformed images and consequently improve the visibility of vascular features. Using tissue mimicking phantoms and measurements on human volunteers, we demonstrate the potential of SMMSF technique in LED-based photoacoustic imaging.
Author(s): Rianne Bulthuis, Sjoukje M. Schoustra, Multi-Modality Medical Imaging, University of Twente (Netherlands); Wiendelt Steenbergen, Biomedical Photonic Imaging, University of Twente (Netherlands); Srirang Manohar, Multi-Modality Medical Imaging, University of Twente (Netherlands)
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In this work we explore the repeatability of our multimodal photoacoustic-ultrasound breast imaging system, called the PAMMOTH imager. The reason to study this feature of the imager, is for proposed longitudinal imaging or serial imaging. This could be in the setting of monitoring physiological changes in the breast caused by neoadjuvant therapy as a means to evaluating the response from the same. In longitudinal imaging, instrumental drifts or other changes over time, as well as factors such as changes during repositioning the breast in the system, are likely to affect images in complex ways. These changes could obscure physiological changes that can be observed. We investigate in a preliminary study how selected factors affect the repeatability. Phantoms are used, as the ground truth to perform the repeat measurements, and images analysed for repeatability. Multiple phantoms with structural and optical differences are made to obtain sufficient variation. Image registration is used wh
Author(s): James A. Tummon Simmons, Kevan L. Bell, Parsin Haji Reza, University of Waterloo (Canada)
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Mid-infrared (MIR) microscopy offers the ability to image many important biological targets including DNA, lipids, collagen, and proteins. Currently, MIR microscopes are limited in scope due to the low lateral resolution of the diffraction-limited MIR focal spot. Photoacoustic remote sensing (PARS) is an emerging imaging technology which can measure non-contact absorption contrast using a second co-focused detection source. In this work, we propose a novel PARS system architecture which leverages a tunable MIR laser for absorption contrast and visible detection laser to achieve high-resolution MIR microscopy. This represents a significant step forward for high-resolution MIR imaging.
Author(s): Naoto Sato, Cyberdyne Inc (Japan); Mithun Kuniyil Ajith Singh, Cyberdyne Inc (Netherlands); Fumiyuki Ichihashi, Yoshiyuki Sankai, Cyberdyne Inc (Japan)
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Peripheral arterial disease (PAD) is a condition affecting a large population globally. It is important to identify and treat PAD at an early stage to avoid further clinical problems. In this work, we demonstrate handheld 3D LED-based photoacoustic/ultrasound imaging of human peripheral vasculature. 850 nm LED arrays and 10 MHz linear array ultrasound probe were used for optical illumination and acoustic detection respectively. We used the system to image micro-vasculature in palm and foot dorsum of a human volunteer. 3D photoacoustic and ultrasound images generated by the system demonstrate its potential in becoming a point-of-care tool for PAD evaluation.
Author(s): Mithun Kuniyil Ajith Singh, Cyberdyne Inc (Netherlands); Naoto Sato, Fumiyuki Ichihashi, Yoshiyuki Sankai, CYBERDYNE Inc (Japan)
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Lymphaticovenous anastomosis (LVA) is a surgical method of redirecting excess lymphatic fluid into the venous system to improve the lymphatic flow and prevent the recurrence of edema. In this work, using phantom and human volunteer experiments, we explore the potential of a portable LED-based dual-wavelength photoacoustic imaging system in 3D visualization of human lymphatic vessels and veins when using ICG as a contrast agent. Our results demonstrate that LED-based photoacoustic imaging system used in this study can visualize and separate lymphatic vessels and veins with high spatial resolution, and thus holds potential in guiding LVA procedure.
Author(s): Maura Dantuma, Srirang Manohar, Univ of Twente (Netherlands)
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We present an overview of regulatory aspects and steps that need to be followed, to prepare the ground for the initiation of first feasibility studies on human subjects. The onus is on a photoacoustic-ultrasound device as intended for breast imaging, exemplified by the PAMMOTH imager. This is a pre-market imaging device and is an example of one developed by academia and university start-ups. While the imaging modality is a specific one and where local practices may be specific, the parallels with other variants of photoacoustic devices and location-specific counterparts of regulatory procedures and bodies, can be made.
Author(s): Shubham Mirg, Haoyang Chen, Sumit Agrawal, Mohamed Osman, Marc Cai, Josiah Minotto, Pennsylvania State University (United States)
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Recently, transparent ultrasound transducers (TUTs) have gained the attention of the photoacoustic imaging community. The ability to illuminate living subjects through the TUT coupled with minimal acoustic coupling allows for miniaturization, reduces cost, and increases the ease of multimodal integrations. Piezoelectric-based TUTs especially are inexpensive, simple to integrate, readily available in flexible shapes and sizes, and exhibit high sensitivity compared to other forms of interferometric and micromachined based TUTs. Piezoelectric TUTs, therefore, have great potential for photoacoustic imaging, however, challenges remain on matching their acoustic sensitivity to conventional opaque piezoelectric transducers. Various noise sources arising from TUT fabrication, electronics, and imaging geometries limit their sensitivity. In this paper, we discuss various TUT specific noise considerations that are detrimental to the signal to noise ratio (SNR).
Author(s): Christopher Nguyen, David L. Kaplan, Srivalleesha Mallidi, Tufts Univ (United States)
Author(s): Jinyun Liu, Haoyang Chen, Sumit Agrawal, Nanyin Zhang, The Pennsylvania State University (United States)
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An integrated functional ultrasound (fUS) and photoacoustic (PA) imaging modality is favorable for obtaining deep brain hemodynamic information. fUS maps blood velocity of microvasculature of deep brain using power doppler frames generated from multiple plane wave angles with high spatiotemporal resolution, while PA as a hybrid modality detects the cerebral oxygen saturation within a few mm depth in the brain. To take advantage of both modalities, fUS and PA imaging modalities are combined to provide a more comprehensive hemodynamics map for preclinical deep brain studies. In this work, we investigated an optimal light delivery geometry to simultaneously acquire fUS and PA frames. Validation studies on ex vivo blood flow phantoms and in vivo mouse brain images with the proposed geometry show a reduced motion artifacts and ease out the coupling challenges, making it suitable for future fUS+PA preclinical imaging studies.
Author(s): Matthew T. Martell, Nathaniel J.M. Haven, Roger J. Zemp, Univ of Alberta (Canada)
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Ultraviolet photoacoustic remote sensing (UV-PARS) microscopy is a non-contact imaging modality capable of producing label-free absorption contrast images of cell nuclei. This virtual hematoxylin-like imaging combined with virtual eosin-like data from 1310 nm scattering microscopy can provide complete virtual H&E histologically in unstained tissues. Here, we develop contour scanning for applying UV-PARS and scattering-based virtual histology in fresh and formalin-fixed thick tissues. Our spectral-domain OCT-guided approach initially scans specimens in 3D, and a custom algorithm extracts the surface contour. A high-resolution UV-PARS scan is then performed using a z-axis stage for dynamic focusing to compensate for sample surface irregularities.
Author(s): Hiroki Hattori, Takeshi Namita, Makoto Yamakawa, Tsuyoshi Shiina, Kyoto Univ. Graduate School & Faculty of Medicine (Japan)
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To evaluate photoaging (damage to elastic fibers in the upper layer of the dermis), photoacoustic images of human skin (25 μm thickness, Kligman criteria G0-G4) sections were obtained. After the upper dermis of these sections was measured using acoustic resolution photoacoustic microscopy (AR-PAM) at visible light region wavelengths, spatial frequency analyses of the upper dermis were conducted. Results clarified that in the early stage of photoaging, high-frequency components increase as photoaging progresses. These analyses demonstrate the feasibility of early diagnosis of photoaging using PAM.
Author(s): Felix Lucka, Centrum Wiskunde & Informatica (Netherlands), University College London (United Kingdom); Maura Dantuma, University of Twente (Netherlands); Saskia C. Kruitwagen, Medisch Spectrum Twente Hospital (Netherlands); Laurens Alink, P.A. Imaging B.V. (Netherlands); Srirang Manohar, University of Twente (Netherlands); Bradley E. Treeby, Ben T. Cox, University College London (United Kingdom)
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The PAMMOTH system is a hybrid multispectral photoacoustic-ultrasound (PA-US) imaging system designed for diagnostic applications in breast cancer imaging. Reconstructing quantitatively accurate, high-resolution PA images for all wavelengths throughout the whole breast comes with a number of challenges, including modeling the US sensor characteristics and accounting for speed-of-sound (SOS) inhomogeneities. Our iterative PA image reconstruction method uses a tailor-made GPU implementation of a pseudospectral time domain method. We examine the influence of all developments on image quality, artifacts and data fit using experimental data from phantoms, volunteers and patients.
Author(s): Doyeon Kim, KRISS/Korea Univ. (Korea, Republic of); Sang-Won Lee, KRISS/UST (Korea, Republic of)
Author(s): David Thompson, Univ of Twente (Netherlands); Michael Jaeger, Institute of Applied Physics, University of Bern (Switzerland); Martin Frenz, Institute of Applied Physics (Switzerland); Srirang Manohar, Univ of Twente (Netherlands)
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We present the application of laser-induced ultrasound (LIUS) transmitters to perform ultrasound computed tomography in conjunction with photoacoustic tomography. A system has been developed to image breast-sized phantoms enabling 2D tomographic imaging of photoacoustic, sound speed and ultrasound reflectivity contrasts. The LIUS transmitter is an integrated unit of an optical fiber and a Polydimethylsiloxane (PDMS) disc doped with carbon black. For the photoacoustic mode, the system is equipped with optical fiber bundles for excitation, with detection using the same piezocomposite detector used in the ultrasound-mode. The results from a test-object demonstrate good agreement with the ground truth.
Author(s): Miguel Sánchez Rodas, Daniel Gallego, Univ Carlos III de Madrid (Spain)
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In this work we have demonstrated the capability of four different commercial HPDL lasers to generate high peak power pulses with a duration of few nanosecond beyond their maximum rating value given at their typical pulse width without causing COD. We have designed, simulated and built a custom high current short pulse driver based on new GaN transistors with a maximum current capacity of 120 A in a range of less than 10 nanoseconds pulse width and a repetition rate of 1 kHz to drive the HPDLs. With the commercial HPDL TPGAU3S09H we have achieved optical pulses with a maximum peak pulse energy of 5.3 microJoule wiht 6 ns pulse width. This corresponds to 391% of their maximum rated peak power demonstrating stable operation without catastrophic optical damage (COD) and improving the typical operation characteristics of the HPDLs as the high-energy short pulses needed for biomedical applications of optoacoustic microscopy and endoscopy.
Author(s): Miguel Sánchez Rodas, Daniel Gallego, ALEXANDER ORAEVSKY, Univ Carlos III de Madrid (Spain)
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In this work a laser ultrasound system was implemented, tested and characterized. As a laser source we used a low-cost high-power laser diode (HPDL) Osram SPL PL90_3. The emitting surface of the laser diode was coated with polydimethylsiloxane (PDMS) layer with carbon nanotubes (CNT) embedded in high concentration and tightly packed. Based on an extremely high optical absorption coefficient of composite PDMS laser with densely loaded CNT and its improved thermoacoustic conversion we achieved a high efficiency of 55kPa/[mJ/cm2] of LUS generation. This work had as main objective to study the viability of the proposed Laser ultrasonic (LUS) source in biomedical imaging and sensing applications. The emitter characterization included the study of the generated acoustic signals with the main attention to short duration non-reverberating pulses and amplitude maximization.
Author(s): Nizar Guezzi, Hyeju Song, Daegu Gyeongbuk Institute of Science Technology (Korea, Republic of); Changho Lee, Chonnam National University (Korea, Republic of)
Author(s): Miya Ishihara, Takeshi Hirasawa, National Defense Medical College (Japan); Tomoki Matsuda, Takeharu Nagai, Department of Biomolecular Science and Engineering, SANKEN, Osaka University (Japan)
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We have succeeded in multicolor photoacoustic imaging of intracellular expressed chromoproteins, which are hRed2.2, ShadowR, ShadowY and ShadowG using an optical-resolution photoacoustic microscopy with a supercontinuum light source, which we developed. When ShadowG and ShadowY in HeLa cells, which are the fluorescent proteins with low fluorescence quantum yield, were imaged, we confirmed that the same distributions of the photoacoustic image and fluorescence image. In the case of the non-fluorescent proteins, hRed2.2 and ShadowR, the fluorescent reporter gene (mTFP) was expressed. We also confirmed that the photoacoustic images of hRed2.2 and ShadowR and fluorescence images of mTFP have the same distribution. Fluorescent probes using fluorescent proteins can visualize various intracellular functions and dynamics. Photoacoustic imaging of chromoproteins have the potential to expand the field of view in the depth direction.
Author(s): Takeshi Hirasawa, Shinpei Okawa, Miya Ishihara, National Defense Medical College (Japan)
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In most of multispectral optical resolution photoacoustic microscopy (OR-PAM), spatial scanning was repeated for each excitation wavelength. To reduce the signal acquisition time, we proposed a new spectroscopic OR-PAM technique that enables to acquire dual information of PA signal intensity and excitation wavelength during single spatial scanning. In the technique, broadband excitation light pulses produced from a supercontinuum light source were added with wavelength-dependent time delay, and then were irradiated to samples to produce PA signals those reflect spectroscopic characteristics of the samples. The spectroscopic OR-PAM technique was demonstrated by performing spectroscopic imaging of optical absorbers with various excitation wavelengths.
Author(s): Sergei Perkov, Stanislav Perevoschikov, Skolkovo Institute of Science and Technology (Russian Federation); Oleg Grishin, Saratov State University (Russian Federation); Rinat O. Esenaliev, University of Texas Medical Branch (United States); Dmitry A. Gorin, Skolkovo Institute of Science and Technology (Russian Federation)
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Hematomas resulted from trauma are very common. Existing treatment techniques have limited efficacy. To improve outcomes, phototherapy (PT) can be used. We studied the effects of phototherapy on bilirubin (BLR) solutions using adsorption (AB) and fluorescent (FL) spectroscopies and optoacoustic (OA). AB, FL, OA signals of BLR-albumin were dependent on exposure time. BLR-albumin absorption decreased exponentially with exposure time, while FL was demonstrated to have complicated dynamics depending on the initial concentration. The results of OA measurements were in good agreement with the in silico study. These results can be used for the optimization of hematomas PT regimes.
Author(s): Sergei Perkov, Dmitry A. Gorin, Skolkovo Institute of Science and Technology (Russian Federation); Rinat O. Esenaliev, Univ of Texas Medical Branch (United States)
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Noninvasive, high-resolution water monitoring in tissues is important for diagnostics and management of diseases and for cosmetic applications. We proposed to use optoacoustics for water monitoring and in this work used combination of high-resolution optoacoustic and ultrasound measurements for probing different layers of skin in vivo. Water-induced optoacoustic response from epidermis, dermis, and subcutaneous tissues was measured in the near-IR spectral range in which water is the major tissue chromophore. High-resolution ultrasound images confirmed probing from these specific layers and depths in skin. This indicates that these techniques combination can be used for high-resolution, accurate water monitoring in tissue layers.
Author(s): Seyed Mohsen Ranjbaran, Department of Physics, University of Isfahan (Iran, Islamic Republic of); Kamran Avanaki, Univ of Illinois at Chicago (United States)
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Our proposed algorithm uses extended formulation of full-waveform inversion (FWI) based on the alternating direction method of multipliers and fluence compensation for accurate image reconstruction. The speed of sound (SOS) map is required in this algorithm as prior information to perform classification and find different regions in the SOS map with equal optical absorption coefficients. The SOS map is generated accurately with another FWI procedure applied on the acoustic data. The fluence map was calculated by Zemax. The algorithm iteratively updates optical absorption coefficients until the data computed with the estimated coefficients match the recorded photoacoustic signals at ultrasonic transducers.
Author(s): Seyed Mohsen Ranjbaran, Department of Physics, University of Isfahan (Iran, Islamic Republic of); Kamran Avanaki, Univ of Illinois at Chicago (United States)
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We have developed a 2D extended formulation of Full-waveform inversion (FWI) based on the alternating direction method of multipliers (ADMM) to estimate the speed of sound (SOS) and acoustic attenuation inside a heterogeneous medium from a circular array of 128 ultrasonic transducers. Our Extended 2D FWI has shown promising results when it is compared with travel time tomography and the classical formulation of FWI.
Author(s): Rayyan Manwar, Kamran Avanaki, Univ of Illinois at Chicago (United States)
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Reconstruction done using limited data from conventional algorithms such DAS, DMAS, p-DAS, TR and UBP will suffer from artifacts. A novel compressed sensing-based algorithm based of alternating direction of directional multiplier (ADMM) is presented in this work which outperforms the conventional method in terms of signal to noise ratio and contrast.
Author(s): Rayyan Manwar, The University of Illinois at Chicago (United States); Kamran Avanaki, Univ of Illinois at Chicago (United States)
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Conventional model-based algorithms are based on building the forward model and then minimizing the cost function with some constrains. In this study, a new approach is proposed. Building the forward model, stabilizing it and then minimizing the cost function. The more stable system provides more stable solution. A small perturbation in the measure of b would not change the solution much if the proposed method is applied.
Author(s): Md Tarikul Islam, Rayyan Manwar, Kamran Avanaki, Univ of Illinois at Chicago (United States)
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We evaluate the use of Thermoacoustic imaging (TAI) for imaging the neonatal brain through fontanelle. We use a 3D human neonatal brain model, an antenna, and a linear array transducer in simulation to characterize the thermoacoustic signal and corresponding reconstructed images. All the characterizations are conducted using Computer Simulation Technology Studio Suite. We characterize the TAI system by using microwave beams with different pulse widths ranging from 0.01µs - 5µs, different frequencies from 1-3 GHz when one of the following types of antenna is used: a horn antenna, a waveguide and a helical antenna.
Author(s): Rayyan Manwar, The University of Illinois at Chicago (United States); Kamran Avanaki, Univ of Illinois at Chicago (United States)
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To fully understand the impact of the skull, we first study the optical properties of the skull in the wavelength range of 690 to 940 nm. Then, the impact of the skull on the ultrasound propagation is evaluated using 2.25 MHz transducers. In a second part, photoacoustic imaging on the frontal, parietal and occipital bones are evaluated. In addition to the skull thickness variation, the angle of illumination and the depth of the imaged target are studied. We determine regions of the human head where transcranial photoacoustic imaging at 2.25 MHz is feasible.
Author(s): Rayyan Manwar, Univ of Illinois at Chicago (United States); Fady Charbel, University of Illinois at Chicago (United States); Kamran Avanaki, Univ of Illinois at Chicago (United States)
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Cerebral oxygenation monitoring in neonates is a measure of diagnosing hypoxia induced brain injuries that may otherwise result into severe neurological disorders. Moreover, the absence of skull bone in neonatal fontanelle area allows to extract oxygen saturation from deeper structures within the brain tissue. Here, we utilized a handheld Transfontanelle photoacoustic probe (TFP) to extract brain oxygen saturation in sheep brain through surgically induced fontanelle in-vivo. The performance was compared to the gold standard arterial blood gas analyzer. High correlation to blood gas analyzer indicates that TFP can be used in neonates for measuring blood oxygen saturation noninvasively.
Author(s): Dan Schonfeld, Kamran Avanaki, Univ of Illinois at Chicago (United States)
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In this study, we have developed an enhancement autoencoder (EAE) utilizing fully convolutional neural network, that can improve the quality of the PA signals received, consequently improving the quality of the reconstructed images. We acquired PAM data from rat brain tissue with both high energy (target data) and low energy (input data) of the laser for training purposes and tested our trained model on PAM data obtained from new rat brains. Our effort is to reconstruct the vascular structure as well as an accurate reading for the blood concentration. The later has been neglected in the previous studies.
Author(s): Ciaran Bench, Ben Cox, UNIVERSITY COLLEGE LONDON (United Kingdom)
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Data-driven approaches to estimating sO2 from photoacoustic images have been successfully implemented in several in silico experiments. However, networks trained on simulated datasets may not produce accurate estimates from real tissues due to differences in the data domains describing real and simulated images. Unfortunately, obtaining a training set of images of real tissues and their accompanying sO2 distributions is non-trivial. However, differences between the data domains can be minimised by improving the simulated data. Here we describe two methods: (1) using unsupervised domain adaptation via Cycle Consistent Adversarial Networks, and (2) generating training data using Ambient Generative Adversarial Networks.
Author(s): Ashkan Javaherian, University College London (United Kingdom); Felix Lucka, Computational Imaging group, Centrum Wiskunde en Informatica (Netherlands); Maura Dantuma, Multi-Modality medical imaging group, TechMed Centre, University of Twente (Netherlands); Rianne Bulthuis, Multi-Modality medical imaging group (Netherlands); Laurens Alink, P.A. Imaging B.V (Netherlands); Jakub Budisky, Department of Computer Systems, Faculty of Information Technology, Brno University of Technology (Czech Republic); Andrejus Michailovas, Ekspla uab (Lithuania); Srirang Manohar, Multi-Modality medical imaging group (Netherlands); Jiri Jaros, Department of Computer Systems (Czech Republic); Brad Treeby, Department of Medical Physics and Biomedical Engineering, University College London (United Kingdom); Ben Cox, Department of Medical Physics and Biomedical Engineering (United Kingdom)
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This study presents our experimental results for a low-cost inversion approach utilizing time-of-flights for a volumetric image reconstruction of the sound speed from ultrasound data collected from the PAMMOTH system. This inversion approach relies on a two point ray tracing scheme. Among two-point ray tracing schemes, shooting methods are popular for UST because of simplicity and accuracy, but their application to 3D case are considered a challenge in seismic applications. We present a shooting method adapted to imaging of the breast tissue from the PAMMOTH ultrasound data. The experimental results are presented, and are discussed regarding accuracy and computational cost.
Author(s): Janek Gröhl, Cancer Research UK , Cambridge Institute (Germany); Lina Hacker, Cancer Research UK , Cambridge Institute (United Kingdom); Ben T. Cox, University College London (United Kingdom)
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There are many reconstruction algorithms for photoacoustic imaging (PAI), with different strengths and weaknesses, and each more suited to some applications than others. A project to compare PAI reconstruction algorithms over a range of scenarios has been established on behalf of the International Photoacoustic Standardisation Consortium (IPASC). In the project (1) each reconstruction algorithm is implemented in the IPASC data format, (2) in silico and clinically-relevant experimental test data sets are collated, (3) the algorithms’ performances are compared using a range of metrics. The results, including the reconstruction codes, data sets, metrics and processing pipeline, will be made publicly available.
Author(s): Mohsin Zafar, Wayne State University (United States); Rayyan Manwar, The University of Illinois at Chicago (United States); Kamran Avanaki, Univ of Illinois at Chicago (United States)
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We have developed a very fast, ultra-wide laser scanning photoacoustic microscopy system that provides a very large active detection area. The system utilizes a novel spiral scanning mechanism, using traditional 2D galvo mirrors to scan an area of ~4cm in less than 5 seconds. To characterize and demonstrate the imaging capability of the system, we image rat brain in vivo.
Author(s): Michelle T. Graham, Muyinatu A. Lediju Bell, Johns Hopkins Univ (United States)
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Precise assessment of nerve injury optimizes outcomes after surgical nerve repair. Photoacoustic imaging is a promising technique for this intraoperative assessment, but is challenged by optical scattering which reduces light penetration into nerve tissue. This work investigates custom light delivery methods to enhance optical penetration into nerve tissue using Monte Carlo simulations. Light sources were positioned in four configurations surrounding the nerve using sparse activation patterns that were evenly distributed or clustered. Results indicate that a custom light delivery system with combined radial and lateral trajectory illumination maximize optical penetration into nerve tissue for intraoperative photoacoustic assessment of nerve injury.
Conference Chair
TomoWave Labs, Inc. (United States)
Conference Chair
Caltech (United States)
Program Committee
Washington Univ. in St. Louis (United States)
Program Committee
Univ. College London (United Kingdom)
Program Committee
Institut Langevin Ondes et Images (France)
Program Committee
Univ. of Cambridge (United Kingdom)
Program Committee
Research Ctr. for Non Destructive Testing GmbH (Austria)
Program Committee
Georgia Institute of Technology (United States)
Program Committee
The Univ. of Texas Medical Branch (United States)
Program Committee
Martin Frenz
Univ. Bern (Switzerland)
Program Committee
National Defense Medical College (Japan)
Program Committee
Pohang Univ. of Science and Technology (Korea, Republic of)
Program Committee
Peking Univ. (China)
Program Committee
National Taiwan Univ. (Taiwan)
Program Committee
Univ. of Twente (Netherlands)
Program Committee
Helmholtz Zentrum München GmbH (Germany)
Program Committee
Univ. of Washington (United States)
Program Committee
Karl-Franzens-Univ. Graz (Austria)
Program Committee
ETH Zurich (Switzerland)
Program Committee
Univ. of Twente (Netherlands)
Program Committee
Univ. of Michigan (United States)
Program Committee
Univ. of Alberta (Canada)
Program Committee
The Univ. of Southern California (United States)
Program Committee
Washington Univ. in St. Louis (United States)