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Conference 12628
Diffuse Optical Spectroscopy and Imaging
25 - 28 June 2023 | Room 5 ICM Ground Floor
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Session 1:
Clinical and Preclinical Applications of Diffuse Optics I
25 June 2023 • 08:30 - 10:00 CEST | Room 5 ICM Ground Floor
Session Chairs:
Thomas D. O'Sullivan, Univ. of Notre Dame (United States), Davide Contini, Politecnico di Milano (Italy)
12628-1
25 June 2023 • 08:30 - 09:00 CEST | Room 5 ICM Ground Floor
Show Abstract +
HEMOCOVID-19 is an international trial, carried on in ten hospitals, with the aim of monitoring endothelial and microvascular impairment in severe COVID-19 patients and general intensive care population, by using non-invasive near infrared diffuse optical spectroscopy. The evaluation of the endothelial health is made by continuously monitoring the local oxygenation of a peripheral muscle, in this case the brachioradialis, while performing a vascular occlusion test. Here, we present the results that demonstrate that microvascular alterations detected at the ICU admission, are correlated with the severity of the pulmonary disease, with the patient outcome (mortality) and antiviral treatments such as Remdesivir.
12628-2
25 June 2023 • 09:00 - 09:15 CEST | Room 5 ICM Ground Floor
Show Abstract +
Blood flow restriction (BFR) training is a technique used to create muscle hypertrophy and strength gains effectively. During BFR training, the blood outflow is restricted in the trained limb while partially allowing blood inflow, through a tourniquet at the limb’s proximal part. BFR pressure values usually lies between 40%-80% of the Limb arterial occlusion pressure. Most of the research studies implement a fixed cuff pressure (50-300mmHg) irrespective of the hemodynamic response of the muscle of the trained limb. We have measured calf muscle of 5 adult healthy participants to understand the hemodynamic response and need for personalized BFR regiments.
12628-3
25 June 2023 • 09:15 - 09:30 CEST | Room 5 ICM Ground Floor
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In this work we present preliminary results to look for standardization of vascular occlusion test (VOT) protocols by evaluating the ability of two VOT protocols to quantify the microvascular reactivity of twelve healthy subjects by means of the hybrid diffuse optical device VASCOVID.
12628-4
25 June 2023 • 09:30 - 09:45 CEST | Room 5 ICM Ground Floor
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In this work we present preliminary results comparing the microvascular reactivity of twenty-one healthy subjects and sixty critically ill patients admitted to the intensive care units by means of the hybrid diffuse optical device VASCOVID. The device provides deeper information regarding tissue perfusion, which is pivotal in tissue wellness, but remains a missing issue in critically ill patients.
12628-5
On demand | Presented live 25 June 2023
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A novel technique to treat different diseases from inflammation to poisonous bites from snakes on small animals is the hyperbaric chamber treatment. Non-invasive and real-time hemodynamic monitoring of patient’s tissue could be useful to quantify the effect of oxygen therapy on the patient. In this pilot study, we explored the possibility of noninvasively detecting canine tissues optical properties by Time Domain Near-Infrared Spectroscopy (TD-NIRS) and then retrieving hemodynamic parameters (deoxygenated and oxygenated hemoglobin molar concentration and tissue oxygen saturation) on different tissues (Triceps Brachii, Biceps Femoralis and Head) of dogs.
Break
Coffee Break 10:00 - 10:30
Session 2:
Clinical and Preclinical Applications of Diffuse Optics II
25 June 2023 • 10:30 - 12:00 CEST | Room 5 ICM Ground Floor
Session Chairs:
Rebecca Re, Politecnico di Milano (Italy), Lorenzo Cortese, ICFO - Institut de Ciències Fotòniques (Spain)
Show Abstract +
We present initial evidence of the SOLUS potential for the multimodal non-invasive diagnosis of breast cancer. First, we show a correlation between the most significant absorption and composition parameters previously identified by the Mann-Whitney U test and the lesion BIRADS. Then, we highlight the importance of multi-wavelength time-resolved Diffuse Optical Tomography and Shear Wave Elastography, in addition to standard B-mode Ultrasound and Color Doppler, for a robust diagnosis of a doubtful malignant lesion. Finally, the significant improvement of sensitivity and specificity adding US-based predictors to the previously optical-only database processed by machine learning shows the key importance of multimodal imaging.
12628-7
On demand | Presented live 25 June 2023
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This study aims at evaluating the effect of NeoAdjuvant Chemotherapy (NAC) on the contralateral tumor-free breast tissue through time domain diffuse optical spectroscopy. The breast tissue composition consisting of hemoglobin, water, lipid and collagen concentrations is quantitatively derived using our seven-wavelength (635-1060 nm) optical mammograph. Preliminary analysis of ten patients' data shows compositional changes occurring in the non-tumor breast in addition to the tumor breast. This includes reduction in breast density and components’ concentrations through the course of the therapy. The final goal is to eventually identify if there is a correlation of these effects with pathological complete response.
12628-8
25 June 2023 • 11:00 - 11:15 CEST | Room 5 ICM Ground Floor
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We use diffuse optical spectroscopic imaging (DOSI) to understand (1) physiological differences between the non-lactating and lactating breast and (2) physiological changes in the breast due to milk extraction. Our data provides unique insight into the dynamics of lactating breast tissue composition and physiology, serving as a foundation for future research, diagnostics, and interventions.
12628-9
On demand | Presented live 25 June 2023
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Monitoring tumors during their growth and disease progression could provide invaluable diagnostic information and improve our understanding of tumors and their microenvironment, especially blood vessels. Hyperspectral imaging (HSI) with integrated three-dimensional optical profilometry (3D OP) provides the necessary tools for non-invasive and contactless disease diagnosis. In this study, we monitored six female BALB/c mice with a subcutaneously grown CT26 murine colon carcinoma over a period of 14 days. Blood vessels in the tumor and its surrounding healthy tissue were segmented from hyperspectral images, and physiological properties such as blood volume fraction and tissue oxygenation were extracted.
12628-10
On demand | Presented live 25 June 2023
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Colorectal cancer (CRC) is the third most common and second most deadly type of cancer worldwide. Mortality can be decreased by using diffuse reflectance spectroscopy (DRS) for real-time cancer margin delineation. Non-invasive label-free guidance of laparoscopic surgery can be conducted to avoid potential complications of open surgery. To the best of our knowledge, we performed the first study to evaluate the tissue chromophore concentrations and scattering properties for application in CRC detection. By combining such evaluation with machine learning models, we have classified tissues with >94% accuracy when probing either tissue layers from ~0.5-1mm and from ~0.5-2 mm deep.
12628-11
On demand | Presented live 25 June 2023
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Fetal hypoxic brain injury is the deprivation of oxygen during labour and is associated with up to 60% mortality. The gold standard of fetal monitoring during labour, the cardio tocograph (CTG) and fetal blood sampling are poor at diagnosing hypoxia continuously and non-invasively. Our research is towards developing a non-invasive, continuous hypoxia assessment system using long wavelength near-infrared spectroscopy through a fiber optic based reflectance. Lactate is a key biomarker for hypoxia determination in babies during birth. For successful implementation of this probe, it is required that it detects lactate in maternal environment and in presence of other spectroscopic interferences. In this paper we look at lactate sensing through a liquid phantom containing spectrally interfering components alongside lactate like glucose, urea, triacetin and albumin. Through these experiments we determine the relevant wavelengths and their combination for effective lactate sensing.
Break
Lunch Break 12:00 - 14:00
ECBO Hot Topics: Light for Life
25 June 2023 • 14:00 - 15:30 CEST | Room 5 ICM Ground Floor
The European Conferences on Biomedical Optics will include a special Hot Topics session. This session, entitled Light for Life, will feature internationally renowned experts discussing the current status of their fields, emerging developments, and how these technologies are poised to improve the human condition.
12631-38
Optoacoustic methods and applications in biophotonics
(Plenary Presentation)
25 June 2023 • 14:00 - 14:15 CEST | Room 5 ICM Ground Floor
12632-85
Optical coherence elastography
(Plenary Presentation)
25 June 2023 • 14:00 - 14:15 CEST | Room 5 ICM Ground Floor
Break
Coffee Break 15:30 - 16:00
Session 3:
Cerebral Hemodynamics and Neural Activity I
25 June 2023 • 16:00 - 17:00 CEST | Room 5 ICM Ground Floor
Session Chairs:
Ilias Tachtsidis, Univ. College London (United Kingdom), Marta Zanoletti, ICFO - Institut de Ciències Fotòniques (Spain)
12628-12
On demand | Presented live 25 June 2023
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In this work we propose a method of processing optical data captured by our bNIRS and DCS instrument, along with physiology data, to assess the severity of hypoxic ischemic (HI) brain injury in a piglet model. This is achieved by means of a machine learning pipeline, which deployed an unsupervised k-means clustering method. We show that the developed pipeline can differentiate between piglets with an HI insult and controls, controls vs mild insult vs severe insult, and mils insult vs severe insult. The work also includes a study of which features lead to the highest algorithm accuracy.
12628-13
25 June 2023 • 16:15 - 16:30 CEST | Room 5 ICM Ground Floor
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We performed diffuse optical neuromonitoring concurrently with invasive neuromonitoring across increasing intracranial pressure (ICP) levels in a pig model of hydrocephalus (n = 25). ICP was progressively increased (up to 60 mmHg). We found that optical critical closing pressure (CrCP) derived with a novel 2-layer Modified Beer-Lambert algorithm was associated (p < 0.001) with intracranial hypertension (ICP ≥ 20 mmHg). No difference was found in CrCP derived with the semi-infinite algorithm (p=0.78) mean arterial pressure (p=0.16), and other diffuse optical metrics. Optical measurement of CrCP obtained from the 2-layer algorithm holds promise for aiding point-of-care diagnosis of intracranial hypertension.
12628-14
On demand | Presented live 25 June 2023
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Critically ill neonates are subjected to severe and abrupt hemodynamic imbalances that could cause cerebral damage. In this population, the need for cerebral monitoring tools to identify dangerous hemodynamic variations in real-time is paramount. Near-infrared spectroscopy (NIRS) is largely exploited in neonatal intensive care units to monitor critically ill patients' cerebral oxygenation. In this ongoing study, we tested a hybrid device that combines time-domain NIRS and diffuse correlation spectroscopy for monitoring absolute cerebral hemoglobin concentration, tissue oxygen saturation, and blood flow index of piglets during induced hemodynamic variations. Cerebral hemodynamic variations were induced during extracorporeal membrane oxygenation procedure, simulating four common conditions affecting ill neonates: hypocapnia, hypercapnia, hypotension, and hypertension.
12628-15
25 June 2023 • 16:45 - 17:00 CEST | Room 5 ICM Ground Floor
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Adverse neurological outcomes are common following cardiac surgical interventions to treat severe congenital heart defects in neonates. Mild-hypothermic cardiopulmonary bypass (MH-CPB) is often used during these surgical interventions. In this study, frequency-domain diffuse optical spectroscopy and diffuse correlation spectroscopy were used to examine the impact of MH-CPB on cerebral blood flow, oxygen extraction fraction, and oxygen metabolism in neonatal swine and identify potential hemodynamic-associated risk factors for neurological injury. The application of physiologic models for diffuse correlation spectroscopy that accounted for profound changes in hematocrit significantly modified assessments of changes in cerebral blood flow and metabolism during MH-CPB.
Poster Session and Lunch Break
26 June 2023 • 12:00 - 13:30 CEST | ICM, Hall B0
Posters will be featured on Monday.
Poster authors: Please set up posters on the morning of your session before or during the morning coffee break. Plan to stand by your poster to discuss it with session attendees during the poster session. Remove your poster following the poster session concludes as posters left on the boards will be discarded.
Poster authors: Please set up posters on the morning of your session before or during the morning coffee break. Plan to stand by your poster to discuss it with session attendees during the poster session. Remove your poster following the poster session concludes as posters left on the boards will be discarded.
12628-54
On demand | Presented live 26 June 2023
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In this work we introduce an analytical way of computing the photon measurement density functions in multilayered flat and spherical media. Comparisons with Monte Carlo simulations in the particular case of two-layered media show very good agreement (differences below 10%), with the additional advantage that the time taken by the theoretical calculations is several orders of magnitude (more than 6) lower than the corresponding Monte Carlo calculations.
12628-55
On demand | Presented live 26 June 2023
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A study used diffuse reflectance spectroscopy (DRS) combined with machine learning to identify oxygenated haemoglobin in chick embryo vessels, which may be a way to identify and study vulnerable plaques. The model had a sensitivity and specificity of 100% and 92%, respectively, in differentiating between arteries and veins using the second derivative of reflectance data. The results suggest that it is feasible to establish a CAM assay as an in vivo model using spectroscopic techniques together with a machine learning algorithm to study the features of atherosclerotic vulnerable plaques.
12628-56
26 June 2023 • 12:00 - 13:30 CEST | ICM, Hall B0
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NeuroDOTpy adapts the existing NeuroDOT toolbox in Matlab (www.nitrc.org/projects/neurodot) to Python in the style of a conventional Python library. NeuroDOTpy addresses challenges of processing functional near infrared spectroscopy (fNIRS) and diffuse optical tomography (DOT) data including the costly MATLAB base license and add-on toolboxes necessary for fNIRS image processing, filtering, modeling, and statistical analysis. The goal of NeuroDOTpy is to provide a data processing toolbox in Python that integrates with many other data processing toolboxes and contains dedicated functions and pipelines for preprocessing, anatomical light modeling, reconstruction, analysis, and visualization.
12628-57
CANCELED: Comparison of the performance of several data fusion methods for the classification of multimodal spectroscopic data collected from skin lesions
26 June 2023 • 12:00 - 13:30 CEST | ICM, Hall B0
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This study presents the results of analysis of diffuse reflectance spectra and autofluorescence spectra obtained in vivo from skin lesions of various types at three different source-detector separations. The results were processed using principal component analysis and traditional machine learning classifiers (support vector machine, linear discriminant analysis, multi-layer perceptron and random forest). Fusion of multimodal data was performed in several ways: fusion of initial data, fusion of features and fusion of decisions. This study presents a comparison of the performance of these data fusion methods in combination with the previous steps of data processing for multiclass classification of skin lesions.
12628-58
26 June 2023 • 12:00 - 13:30 CEST | ICM, Hall B0
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Reabsorption and reemission of fluorescence light affects the time trace of the emission on the ps to ns time scale. We evaluated fluorescence decay curves after reabsorption events to determine correction factors for time resolved fluorescence spectroscopy based on a rate equation model. The results indicate that reabsorption can be quantitatively determined and concentration and depth information can be reconstructed from the time-course of the fluorescence signal. The applicability of the proposed technique to obtain information on the depth of signal generation in tissue and/or determination of reabsorbing structures with time-resolved fluorescence tomography is discussed.
12628-59
On demand | Presented live 26 June 2023
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An original bench based on the measurement of Photoplethysmography (PPG) and Diffuse Reflectance Spectroscopy (DRS) is presented. Thanks to this setup, we were able to investigate several sensor configurations in terms of source-detector distances and wavelength at kHz acquisition frequency. These measurements are multi-wavelength in visible light and near infrared, performed on three configurable source-detector distances and synchronized. We will additionally present the first measurements obtained on a representative and dynamic medium. This work opens interesting perspectives for physiological measurements on persons and sensor development.
12628-60
On demand | Presented live 26 June 2023
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Steatosis, or fat accumulation in the liver, characterized by presence of fat droplets in the cytoplasm of hepatocytes is a common and potentially serious condition that can lead to liver damage and other health complications. Gold standard method for steatosis assessment includes an invasive biopsy and a subjective anatomopathological analysis. In this work we present a new non-invasive method based on near infrared diffuse reflectance spectroscopy to assess the fraction of hepatocytes affected by steatosis from relative quantification of fat. The results obtained with this method show good agreement with the gold standard anatomopathological analysis.
12628-61
26 June 2023 • 12:00 - 13:30 CEST | ICM, Hall B0
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Cancers of the upper gastrointestinal (GI) tract remain a major contributor to the global cancer risk. In this study, a sterilisable diffuse reflectance spectroscopic fibre probe is used for tissue characterisation intraoperatively during upper gastrointestinal cancer surgery. Histopathology correlation is enabled by the surgeon marking the optical probed tissue locations after the acquisition of spectral data. The data is normalised, and significant features are automatically selected to improve tissue discrimination accuracy. Supervised machine learning algorithms are used for discrimination between tumour and non-tumour tissue and evaluated in terms of accuracy, sensitivity, specificity, and the area under the curve.
12628-62
On demand | Presented live 26 June 2023
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Currently, surgeons do not have real-time noninvasive methods for intraoperative visualization of cerebral blood flow, which is critically important in neurosurgical operations. Laser speckle contrast imaging may be promising for solving this problem. In the present study, this method was demonstrated for the evaluation of acute cerebral blood flow abnormalities in laboratory animals. A distinct reduction in cerebral blood flow and a difference in blood supply in the hemispheres was shown when both carotid arteries were clamped. The results obtained show the prospects of using LSCI for the control of acute disorders of cerebral blood flow during neurosurgical operations in real-time.
12628-64
26 June 2023 • 12:00 - 13:30 CEST | ICM, Hall B0
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Imaging fluorescent probes in the short-wave infrared (SWIR) range (1000-1700nm) has the advantage of low scattering and tissue absorption, leading to an improvement in depth penetration and image resolution. Due to this, SWIR imaging is being used to generate semi-quantitative distribution maps of injected fluorescent probes in live animals. In the present study, we aim to develop a theoretical model to extract quantitative fluorescence concentration values from the received fluorescent intensity signals at different depths within the biological sample. These results will support the development of image-based pharmacokinetics and bio-distribution models for preclinical drug development. The ability to non-invasively determine blood or tissue concentrations of fluorescent molecules within live animals has the potential to drastically reduce the time and cost of research, and avoid the need for animal sacrifice a different time points plus complicated bioanalysis tissue, ex-vivo.
12628-65
26 June 2023 • 12:00 - 13:30 CEST | ICM, Hall B0
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The TinyBrains project aims to develop a hybrid multimodal device to continuously and non-invasively monitor at-risk infants in a tomographic manner.
12628-66
On demand | Presented live 26 June 2023
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The light propagation in three-dimensional scattering media was studied based on solutions of Maxwell’s equations and the radiative transfer equation. The light distribution of laterally infinitely extended slabs was calculated versus depth for an incident plane wave. The energy density obtained by a numerical solution of Maxwell’s equations was compared to the fluence rate calculated by an analytical solution of the radiative transfer equation for different concentrations of spherical particles in the slab. In general, a good agreement between the energy density and the fluence rate was found.
12628-67
26 June 2023 • 12:00 - 13:30 CEST | ICM, Hall B0
12628-68
On demand | Presented live 26 June 2023
Show Abstract +
In this work we derive general equations for the analytical calculation of photon mean partial pathlengths (MPPLs) in turbid media with an arbitrary number of layers. Comparisons with their Monte Carlo (MC) counterpart show excellent agreement. These quantities can now be used to retrieve haemoglobin concentrations changes in cerebral blood in real-time and with minimal computing requirements.
12628-70
On demand | Presented live 26 June 2023
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The laser speckle imaging technique with sub-pixel correlation analysis allows to identify changes in the sterile zone radius, and makes it possible to predict these changes significantly earlier than the disk diffusion method which is recommended by the European Committee on Antimicrobial susceptibility testing (EUCAST). Results are oriented towards speeding and facilitating epidemiological analysis.
Acknowledgments
This work has been supported by the European Regional Development Fund projects “Rapid assessment system of antibacterial resistance for patients with secondary bacterial infections” (No. 1.1.1.1/21/A/034) and “Fast and cost-effective machine learning based system for microorganism growth analysis” (No.1.1.1.1/19/A/147).
12628-71
On demand | Presented live 26 June 2023
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The photoacoustic guided (PAG) technique can noninvasively increase light penetration and localization in deep tissue. The mechanism of the PAG technique is considered to be a pressure dependent refractive, but it is still a highly controversial issue. We assumed that the change in the refractive index or anisotropy factor of scattering in the PAG region contributes to the light guiding effect. Both the refractive index and anisotropy factor heterogeneities increase the photon density in the PAG region of the deep tissue part. The effect of localization of the photon density in the PAG region with the anisotropy factor heterogeneity is less significant compared to that with the refractive index heterogeneity.
12628-72
On demand | Presented live 26 June 2023
Show Abstract +
Time-domain diffuse optical tomography (TD-DOT) systems use pulsed lasers and measure time-varying tem-
poral point spread function to estimate spatially varying optical parameters in biological tissues. Generally, the
TD-DOT systems have been based on picosecond light sources and measurements were performed using photon
counting methods or time-gated detectors. In this work, we demonstrate the feasibility of TD-DOT using a
nanosecond laser source and measurements using a standard digital oscilloscope. For this, we constructed a
prototype TD-DOT experimental system utilising a high-energy nanosecond Nd:YAG laser combined with a
high-bandwidth oscilloscope. The system was used to image an optical phantom. The experiment verified that
both absorbing and scattering objects can be simultaneously reconstructed with nanosecond TD-DOT.
12628-73
26 June 2023 • 12:00 - 13:30 CEST | ICM, Hall B0
Show Abstract +
Diffuse Reflectance Spectroscopy (DRS) can enhance spine surgery by providing reliable tissue feedback in real time. So far, research has been limited to conventional DRS probes equipped with two parallel optical fibers. To overcome the limitations of these probes and enable integration with existing spine surgical devices, we have designed a customized DRS probe by protruding the collecting fiber beyond the emitting fiber.
With our results from Monte Carlo simulations and optical phantom experiments, we demonstrate how this modified fiber layout affects the probed volume while still detecting proximity to the cortical layer. This suggests that our customized fiber optic probe could facilitate the integration of DRS into the surgical workflow without compromising tissue feedback reliability.
12628-74
26 June 2023 • 12:00 - 13:30 CEST | ICM, Hall B0
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Strong light scattering by tissues significantly limits optical analysis and treatment methods. Recently, ultrasound light waveguiding has been demonstrated as a promising technique towards light manipulation in scattering samples. The configurations presented so far focused on a transmission geometry, where light and ultrasound propagation directions are perpendicular. However, for a range of applications only single-sided access to the sample is available. In this contribution we discuss the opportunities and challenges of applying ultrasound light waveguiding in a single-sided access geometry.
12628-75
On demand | Presented live 26 June 2023
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Development of a LED-based precise method to determine the optical properties of scattering media between 850 an 1000~nm. The optical properties determined with our sensor and with an standard integrating sphere device are compared.
12628-76
On demand | Presented live 26 June 2023
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RGB imaging is a non-invasive technique that is able to monitor hemodynamic brain responses following neuronal activation during neurosurgery. These cameras are often present in operating rooms, but a robust quantification is complicated to perform during neurosurgery. Liquid blood have been proposed, but it is not possible to model hemodynamic responses similar to those that occur in the brain. To overcome this issue, we propose a 3D brain model, including activated, non-activated grey matter and temporal hemodynamic fluctuations using Monte Carlo simulations. Several setups were modeled to evaluate their impact for identifying activated brain areas using statistical parametric mapping.
12628-77
26 June 2023 • 12:00 - 13:30 CEST | ICM, Hall B0
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The peculiar features of Time Correlated Single Photon Counting (TCSPC) have made this tool a key element in a great variety of applications, but its speed limits still prevent its exploitation in many other advanced applications. Historically, limiting the acquisition rate of a single TCSPC channel was considered the only way to avoid the so-called pile-up distortion. In this work we present a completely new approach able to remove any constraint on TCSPC while guaranteeing negligible distortion at any operating rate. This solution opens the way to the development of novel ultrafast TCSPC instrumentation.
12628-78
On demand | Presented live 26 June 2023
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Hyperspectral imaging (HSI) is an optical technique that processes the electromagnetic spectrum at a multitude of monochromatic, adjacent frequency bands. Recently, HSI was used to differentiate between healthy and pathological tissue under operative conditions in a surgery room on patients diagnosed with brain tumors. In this article, we perform a statistical analysis of the brain tumor patients' HSI scans from the HELICoiD dataset with the aim of identifying the correlation between reflectance spectra and absorption spectra of tissue chromophores. By using the principal component analysis, we determine the most relevant spectral features for intra- and inter-tissue class differentiation. Furthermore, we demonstrate that such spectral features are correlated with the spectra of cytochrome, i.e., the chromophore highly involved in (hyper) metabolic processes. Identifying such fingerprints of chromophores in reflectance spectra is a key step for automated molecular profiling.
12628-79
On demand | Presented live 26 June 2023
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Laser speckle contrast imaging (LSCI) methods are extensively used in assessment of blood flow to detect various pathological conditions in different parts of human body. In contrast to LSCI being deployed for larger region of interest (few centimeters), we present a laser speckle imaging at microscopic level. Rather than utilizing the conventional speckle contrast, we use intensity auto-correlation using recently developed Multi-step Volterra Integral method(MVIM) to quantify the micro-perfusion. The proposed laser speckle correlation microscopy (LSCM) system is validated using microfluidic flow phantom experiments.
12628-80
On demand | Presented live 26 June 2023
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For the prediction of the scalp-cortex correlation (SCC), the influence of the extracerebral tissues on light propagation in the brain is important. The three-layered infant head models in which the scalp, skull, and cerebrospinal fluid are combined as a homogeneous tissue are constructed to investigate the influence of the thin extracerebral tissues on the prediction of the SCC. The influence of the extracerebral tissues on the SCC of infants is less significant than that of adults. The three-layered head model is practically useful to predict the acceptable SCC of the functional near-infrared spectroscopy measurements of infants.
12628-81
On demand | Presented live 26 June 2023
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In the framework of the HyperProbe consortium, we present a full optical characterisation of ex vivo glioma tissue from surgery biopsies, using both hyperspectral imaging (HSI) via a in-house, high-spectral density HSI device and conventional spectroscopy using a commercial spectrophotometer. The spectral characterisation of glioma tissue aims at identifying optical signatures of known and novel biomarkers to be used to infer the physiological and pathological state of the tissue. Such method can provide benefits for tumour identification and differentiation during neuronavigation in glioma resection aided by HSI, as well as to optimise and promote the design of tailored hyperspectral technology for such purpose, which is the primary objective of the HyperProbe project.
12628-82
On demand | Presented live 26 June 2023
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We report on vein imaging simulation studies using Zemax OpticStudio simulation software. These simulations
are done using a 9-layer skin model. All the parameters save the thickness are wavelength dependent, and the
simulation was considered at three different wavelengths – 650nm, 780nm, and 850nm. For the vein in a given
layer and at a given incident wavelength, the source-lens-detector setup was placed at various angles. Simulation
results show the angle-dependent penetration of near-infrared (NIR) light into the skin and provide design inputs
on the optimum wavelength and angle for vein illumination.
12628-83
On demand | Presented live 26 June 2023
12628-84
On demand | Presented live 26 June 2023
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We present a digital instrument simulator (DIS) developed to optimize both the hardware and data processing pipeline of a novel hyperspectral imaging system designed for neurosurgery application. This DIS is based on a 2-step framework. Firstly, Monte-Carlo simulations are run to produce an ideal dataset of the photon transport in tissue. Then, the raw output parameters of the simulations, such as the exit positions and directions of the photons, are processed to take into account the physical parameters of an instrument in order to produce realistic images and test various scenarios.
12628-85
On demand | Presented live 26 June 2023
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Aging is characterized by a decay in muscle mass and strength, which becomes steeper after 50 years and represents a risk factor for the development of morbidities at older age. The “Trajector-AGE” project aims to monitor the progression of neuromuscular decline, defining possible biomarkers, by studying muscle health in middle-aged (55-60 years) and old (75-80 years) populations. Among the techniques employed, time-domain near infrared spectroscopy (TD-NIRS) and diffuse correlation spectroscopy (DCS) allow to non-invasively assess muscle oxidative metabolism and perfusion, respectively. This work represents a case study on the results obtained from the application of these techniques on one volunteer.
12628-87
On demand | Presented live 26 June 2023
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Protoporphyrin IX (PpIX) is a fluorophore being currently used to localize tumoral tissues. The tissue is usually excited at one wavelength, e.g., 405 nm, and the fluorescence signal is used to estimate the amount of PpIX during surgery. However, other fluorophores (baseline) whose emission spectra are close to the one of PpIX impair the quantification of PpIX and consequently the tissue pathological status classification. An efficient multi-excitation wavelengths method, free from any a priori on the baseline composition, has been proposed to cope with this issue. This method requires decorrelated measurements in the range of PpIX emission at multiple excitation wavelengths. We investigated the influence of the source bandwith on this deccorelation by comparing
two experimental setups using either LED or laser diode sources. In average, the experimental setup using laser diodes for excitation increases the decorrelation by 35.3% compared to the one using LEDs.
12628-88
On demand | Presented live 26 June 2023
Show Abstract +
Heavy menstrual bleeding (HMB) affects 20-30% of women of reproductive age. One hypothesis suggests that a lack of hypoxia in the endometrium at menstruation could be the cause.
We demonstrate a prototype fibre optic probe for oxygen measurement in the uterus with multiple locations for light side emission and collection. Spectral transmission measurements through tissue aims to reveal haemoglobin oxygen saturation. The ability to monitor at various depths, allows comparison between the endometrium layer and the deeper myometrium muscular outer layer revealing the expected (or defective) relative hypoxia in the endometrium.
12628-89
26 June 2023 • 12:00 - 13:30 CEST | ICM, Hall B0
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The first ever commercial multi-frequency quantitative NIRS (QNIRS) device is presented, providing real-time data analysis. The QNIRS calculates absolute absorption and reduced scattering coefficients and is capable of quantitative full head tomography, due to its scalable and modular design.
The monitoring of relative changes with respect to an arbitrary initial state is an obstacle which has been virtually impossible to overcome in clinical applications. Only absolute values of tissue oxygenation in % (haemoglobin in molar) provides an acceptable information in a clinical practice
A new QNIRS device is presented that addresses the medical environment needs providing real-time absolute measures of tissue optical properties.
12628-90
On demand | Presented live 26 June 2023
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Usually, in biomedical optics, the average fluence rate of photons, evaluated in a subvolume of a propagating medium, is obtained by Monte Carlo simulations by calculating the power deposited by photons absorbed in the subvolume. We propose and analytically demonstrate an alternative method based on evaluating the average path length traveled by all photons injected within the subvolume. Application examples are given. This method also works for a zero absorption coefficient and a non-constant spatial distribution of the absorption coefficient within the subvolume.
12628-91
On demand | Presented live 26 June 2023
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The analytical benchmark provided by the invariant mean path length law spent by light injected with uniform Lambertian illumination within nonabsorbing scattering media is used to verify Monte Carlo (MC) codes developed for biomedical optics applications. The correctness of an MC code can be evaluated with a sample t-test. In addition, the invariance of the mean path length ensures that the expected value is known regardless of the complexity of the medium. The obtained results show that the accuracy of the estimated mean path length can progressively increase as the number of simulated trajectories increases.
12628-92
On demand | Presented live 26 June 2023
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Deep-learning diffuse optical tomography is a non-invasive diagnostic method that uses deep-learning algorithms and near-infrared radiation to detect breast tumors. However, DL-DOT has several limitations. The limitations include using only homogeneous datasets and severe overfitting of the prediction model. To overcome these challenges, a regularized nested UNet++ algorithm is employed, effectively addressing the DOT inverse problem in inhomogeneous breasts. Results show an enhancement of close to one order of magnitude in regularized neural network's tumor detection performance, compared to non-regularized neural networks, emphasizing the importance of regularization for breast tumor detection and improving the accuracy of DOT image reconstruction.
12628-93
On demand | Presented live 26 June 2023
Show Abstract +
In this work, we aim to develop a virtual platform to compare the performance of the different manifestations of photon Time of Flight Spectroscopy namely Direct, Indirect and Interferometric photon Time of Flight Spectroscopy (pToFS). Extending the comparison over a range of scenarios, defined by a matrix of optical properties (dubbed here as Virtual Tissue), allows for the definition of different use cases for each of these techniques. The effect of parameters like temporal drift, exposure time and background noise will also be studied.
12628-95
26 June 2023 • 12:00 - 13:30 CEST | ICM, Hall B0
Show Abstract +
A multidistance, multiwavelength, compact speckle contrast optical spectroscopy (SCOS) system is presented as a non-invasive monitor of blood flow and oxygenation.
12628-97
On demand | Presented live 26 June 2023
Show Abstract +
We present a novel approach that combines Monte Carlo simulations to propagate photons in a turbid media having the dynamics modelled using stochastic differential equations, resulting in simulating diffuse laser speckles for in-vivo blood flow imaging applications. The proposed method allows to model the tissue dynamics with a pre-defined probability density function and spatially varying autocorrelation.
12628-98
On demand | Presented live 26 June 2023
Show Abstract +
In this study, deep learning-based imputation has been proposed to address the trade-off between the accuracy of blood flow measurement and the temporal resolution of the imaging system. The acquisition of speckle images at denser exposures eventually leads to better quantification of blood flow. But in this process, the temporal resolution of the system will be compromised. As a result, generative adversarial imputation network (GAIN) has been utilized to performs imputation to generate a finer multi-speckle contrast data from a coarser measurement which results in improved estimation of characteristics decay time of the sample (τc) and eventually temporal resolution of the imaging system has been improved by 10 times.
ECBO Plenary
26 June 2023 • 14:00 - 15:30 CEST | Room 5 ICM Ground Floor
This plenary session features presentations by Melissa Skala and YongKeun Park.
12627-122
Fluorescence lifetime imaging of NAD(P)H and FAD to monitor immune cell metabolism and function
(Plenary Presentation)
26 June 2023 • 14:05 - 14:45 CEST | Room 5 ICM Ground Floor
Show Abstract +
We demonstrate optical redox ratio and fluorescence lifetime imaging microscopy of intrinsic metabolic co-factors NAD(P)H and FAD to quantify metabolic changes in human immune cells from peripheral blood. This approach is attractive because it does not require cell surface labels or transfection, enabling rapid assessment of single cell metabolism. Newly trained neural networks automatically segment single cells for analysis of heterogeneity within and between patients. Overall, this approach is attractive for both basic research and patient management in cancer and immunology.
12627-123
Holotomography and artificial intelligence: label-free 3D imaging, classification, and inference of live cells and organoids
(Plenary Presentation)
26 June 2023 • 14:45 - 15:25 CEST | Room 5 ICM Ground Floor
Show Abstract +
Holotomography (HT) is a powerful label-free imaging technique that enables high-resolution, three-dimensional quantitative phase imaging (QPI) of live cells and organoids through the use of refractive index (RI) distributions as intrinsic imaging contrast1-3. Similar to X-ray computed tomography, HT acquires multiple two-dimensional holograms of a sample at various illumination angles, from which a 3D RI distribution of the sample is reconstructed by inversely solving the wave equation. By combining label-free and quantitative 3D imaging capabilities of HT with machine learning approaches, there is potential to provide synergistic capabilities in bioimaging and clinical diagnosis. In this presentation, we will discuss the potential benefits and challenges of combining QPI and artificial intelligence (AI) for various aspects of imaging and analysis, including segmentation, classification, and imaging inference3-6. We will also highlight recent advances in this field and provide insights on future research directions. Overall, the combination of QPI and AI holds great promise for advancing biomedical imaging and diagnostics.
Break
Coffee Break 15:30 - 16:00
Session 4:
Cerebral Hemodynamics and Neural Activity II
26 June 2023 • 16:00 - 17:00 CEST | Room 5 ICM Ground Floor
Session Chairs:
Wesley B. Baker, The Children's Hospital of Philadelphia (United States), Yoko Hoshi, Hamamatsu Univ. School of Medicine (Japan)
12628-16
On demand | Presented live 26 June 2023
Show Abstract +
In this work, the authors present a simulation study to evaluate the feasibility of using Time Domain functional Near-Infrared Spectroscopy (TD fNIRS) to monitor hemodynamic oscillations in biological tissues like the cerebral cortex. Two geometries (slab and two-layer medium) were considered to define the optimal acquisition parameters and to assess the ability of the technique to detect and separate oscillations occurring at different depths within the probed medium by exploiting the time-gating of TD fNIRS signals.
12628-17
On demand | Presented live 26 June 2023
Show Abstract +
This work aims to show the possibility to perform in-vivo acquisitions with high sampling rate (20 Hz) with Time Domain functional Near-Infrared Spectroscopy (TD fNIRS) for studying brain resting state oscillations. We acquired 13 healthy volunteers during normal and forced respiration and the (PSD) for systemic and cortical O2Hb and HHb concentrations were successfully calculated with a single measure. Specific characteristic peaks were evaluated in the cardiac, respiratory, low, and very low frequency bands.
12628-18
26 June 2023 • 16:30 - 16:45 CEST | Room 5 ICM Ground Floor
Show Abstract +
Understanding the electrical and hemodynamic coupling during cortical slow waves can be very useful and relevant. In this work, we displayed and quantified the fluctuations generated in the cerebral blood flow during slow wave activity in the cortex due to neurovascular coupling. We developed a setup that can simultaneously monitor hemodynamics and multiunit electrophysiology in rodents, and thereby, explored the relationship between the neuronal and hemodynamic activities during slow wave. We also presented the evoked responses in both hemodynamics and neuronal activity due to cortical electrical stimulation, which can allow us to attain a more precise relationship between them.
12628-19
On demand | Presented live 26 June 2023
Show Abstract +
Functional near infrared spectroscopy (fNIRS) delivers a flexible, portable, and wearable technique for monitoring brain function in situations where fMRI is not feasible, not suitable, or inaccessible. However, variations in optode locations and head shapes and sizes throughout development lead to considerable challenges in group-based and longitudinal studies that generally use either channel-focused analyses or image reconstruction techniques that require strong participant-atlas correspondence. We present a scalp-based parcellation technique that compensates for variation in optode array placement and general head morphology and accounts for fNIRS spatial sampling with minimal assumptions about the underlying head and brain structure to support robust statistical analyses.
Session 5:
Cerebral Hemodynamics and Neural Activity III
27 June 2023 • 08:30 - 10:00 CEST | Room 5 ICM Ground Floor
Session Chairs:
Yoko Hoshi, Hamamatsu Univ. School of Medicine (Japan), Jana M. Kainerstorfer, Carnegie Mellon Univ. (United States)
12628-20
Whole-head high-density diffuse optical tomography in infants
(Invited Paper)
27 June 2023 • 08:30 - 09:00 CEST | Room 5 ICM Ground Floor
Show Abstract +
High-density diffuse optical tomography (HD-DOT) can be used to study the infant brain during critical periods of development. We have developed HD-DOT headgear capable of sampling across the entire scalp surface. Preliminary tests in 6-month-old infants demonstrate that obtaining high quality, whole-head HD-DOT data in infants is now possible. Our focus now is to use whole-head HD-DOT to perform high-precision infant brain mapping in ecologically-valid settings.
12628-21
On demand | Presented live 27 June 2023
Show Abstract +
Anemia is a common problem in preterm neonates and red blood cell transfusion (RBCT) is used to improve oxygen delivery. To limit the risk of possible complications new strategies to minimize the need for RBCTs are needed, as assessment of hemoglobin concentration in blood appears to be an inadequate biomarker. In this study, cerebral oxygenation, blood flow and oxygen metabolism were measured in 18 preterm neonates before and after transfusion by a non-invasive hybrid device that combines time-domain NIRS and diffuse correlation spectroscopy techniques. Results show an increase in saturation due to RBCTs but insignificant changes in cerebral oxygen metabolism.
12628-22
27 June 2023 • 09:15 - 09:30 CEST | Room 5 ICM Ground Floor
Show Abstract +
Hyperoxic cardiopulmonary bypass (CPB) is common in neonates undergoing cardiac surgery. Hyperoxemia has been shown to potentially generate injurious reactive oxygen species in the brain that contribute to adverse neurological outcomes. Normoxemia, however, might not deliver adequate oxygen to support brain metabolism. In this study, we examine the impact of hyperoxemic versus normoxemic CPB on cerebral oxygen content and neurologic injury biomarkers in neonatal swine. We collected non-invasive optical cerebral neuromonitoring to examine cerebral oxygen content alongside cerebral microdialysis assessments of neurological injury. Hypothesis: Hyperoxic CPB will result in increased cerebral oxygenation and increased neurological injury.
12628-23
27 June 2023 • 09:30 - 09:45 CEST | Room 5 ICM Ground Floor
Show Abstract +
Functional diffuse correlation spectroscopy (fDCS) and electroencephalography (EEG) have shown distinct advantages in studying the infant´s brain. In this work, we used a 16-channel fDCS device and 128-sensors Geodesic EEG system to test the feasibility of measuring task-triggered responses in infants. We examined neural responses to visual stimuli (e.g., checkerboard display) and to speech stimuli presented in an alternating/non-alternating design. Our preliminary results of 46 infants found a strong neural response to visual stimuli in the occipital region, showing increased cerebral blood flow and visually evoked responses. This suggested that the fDCS-EEG setup is promising for exploring cognitive function in infants.
12628-24
On demand | Presented live 27 June 2023
Show Abstract +
Combining multidistance diffuse correlation spectroscopy (DCS) and time-resolved near-infrared spectroscopy (trNIRS) allows for depth-enhanced, simultaneous monitoring of multiple cerebral hemodynamic parameters related to cerebral autoregulation; however, optical methods can be confounded by signal contamination from extracerebral tissue. This study aimed to evaluate extracerebral signal contamination in trNIRS/DCS data acquired during transient hypotension. Results show significantly larger blood flow and oxygenation changes in the extracerebral tissue compared to the brain, demonstrating the importance of using depth-enhanced methods that account for extracerebral signal contamination.
Break
Coffee Break 10:00 - 10:30
Session 6:
Theory, Algorithms and Modeling I
27 June 2023 • 10:30 - 12:00 CEST | Room 5 ICM Ground Floor
Session Chairs:
Dirk Grosenick, Physikalisch-Technische Bundesanstalt (Germany), Federico Tommasi, Univ. degli Studi di Firenze (Italy)
12628-25
On demand | Presented live 27 June 2023
Show Abstract +
Optical imaging is a non-invasive technique that is able to monitor hemodynamic and metabolic responses during neurosurgery. However, a robust quantification is complicated to perform. To overcome this issue, phantoms that mimic biological tissues are required for the development of imaging systems in order to reach a true standardization. In this work, we explore the possibility to use a combined liquid blood phantom with cytochrome contained yeast to evaluate the reliability of hyperspectral imaging to measure oxygenation and metabolic changes. This phantom can be used to verify the reliability of intraoperative optical setups before moving on to clinical application.
12628-26
On demand | Presented live 27 June 2023
Show Abstract +
We propose a novel analytical time-domain model for migration of Raman scattered photons in inhomogeneous
two-layer diffusive media. Based on this model, the methods for reconstruction of the Raman spectra of the two
layers are developed, tested on simulations and validated on phantom measurements data. For the first time, the model-based reconstruction of the Raman spectra of the two-layered medium was performed.
12628-27
On demand | Presented live 27 June 2023
Show Abstract +
We present an application of Fourier space analysis to determine overall order of tissue architecture in samples of murine abdominal walls. In brief, hyperspectral microscopy images of hematoxylin and eosin stained histological slides are acquired and Beer-Lambert law is used to calculate relative volume fraction maps of both stains. A Fourier space representation of the eosin image is calculated, and differences between healthy and diseased subjects are quantified in the Fourier space through the ellipticity of spatial frequency distribution. The proposed metric discriminates between healthy and diseased subjects and is strongly correlated to macroscopic scattering properties.
12628-28
27 June 2023 • 11:15 - 11:30 CEST | Room 5 ICM Ground Floor
Show Abstract +
The first framework for real-time multi-parameter deep-learning diffuse optical tomography (DL-DOT) is presented. Enabled by high-speed FD measurement and bulk optical property recovery, the proposed CNN model predicts absorption/reduced-scattering comparable to conventional iterative model-based tomography, with 87% accuracy. Furthermore, the time taken to perform a single reconstruction is reduced by an order of magnitude as compared to conventional tomography. This facilitates high-resolution multi-parameter 3D optical imaging in real-time, providing important feedback for point-of-care clinicians, and thereby improving the speed, efficiency, and cost of disease diagnosis and monitoring.
12628-29
On demand | Presented live 27 June 2023
Show Abstract +
Infant head injuries and damage can be caused by various factors such as tumors or physical trauma. The treatment for a head injury will depend on the severity of the damage. As a result, the infant's head should be imaged before any treatment. High-density diffuse optical tomography (HD-DOT) is a non-invasive imaging technology that can be employed for subsurface imaging of the infant's brain. In this study, we propose an improvement of subsurface imaging of the infant's head, using an extreme gradient boosting (XGBoost) algorithm combined with HD-DOT achieving a similarity index greater than 0.97 in terms of cosine similarity.
12628-30
On demand | Presented live 27 June 2023
Show Abstract +
Diffuse Optical Tomography (DOT) is an imaging method that utilizes near-infrared light to image the human body.One of the most promising methods to solve DOT is deep learning, due to its high computational power and fast inference. However, the ill-posed nature of the problem and the non-uniqueness of its solution can pose challenges in learning the inverse transformation. To address these challenges, two main approaches are used: learning the forward mapping and then applying classical inversion techniques, or directly learning the inverse mapping. In this study, both approaches were applied on a realistic breast model to evaluate the impact of dataset size on the optimal technique for DL-DOT. The results showed that for the specific scenario the direct inversion approach was superior for large datasets (over 2K), improving the RMSE and CNR by 44% and 97%, while the forward optimization approach was better for smaller datasets (150), improving both the RMSE and CNR by 10% and 67%.
Break
Lunch Break 12:00 - 14:00
World of Photonics Plenary
27 June 2023 • 14:00 - 15:30 CEST | Room 1 ICM Ground Floor-1st Floor
This plenary session features a presentation by Tammy Ma and Constantin Haefner on laser-driven inertial confinement fusion.
Break
Coffee Break 15:30 - 16:00
Session 7:
Advances in Instrumentation and Technology I
27 June 2023 • 16:00 - 17:15 CEST | Room 5 ICM Ground Floor
12628-31
Ultra-portable, fast and low-cost blood flow meter
(Invited Paper)
27 June 2023 • 16:00 - 16:30 CEST | Room 5 ICM Ground Floor
Show Abstract +
We present an ultra-portable blood flow meter device based on speckle contrast optical spectroscopy. The device comprises of low-cost, off-the-shelf components and can measure fast pulsatile microvascular blood flow in real-time. We will discuss features, capabilities and the software of the device and show data of fast pulsatile blood flow measured from forearm of a subject and discuss high signal to noise ratio in the measurement. Such a portable and affordable device can make huge impact for markets such as the blood flow restriction for muscle training/therapy as well as continuous bedside monitoring of cerebral blood flow.
12628-32
On demand | Presented live 27 June 2023
Show Abstract +
In this abstract, we present a test platform based on speckle contrast optical tomography for high-density, continuous, non-invasive, point-of-care mapping of the microvascular cerebral blood flow (CBF). We demonstrate the ability of the platform to acquire data from phantom and in vivo from a single region. We will show easy scalability of our platform for large brain area coverage, which will be demonstrated in the next update.
12628-33
27 June 2023 • 16:45 - 17:00 CEST | Room 5 ICM Ground Floor
Show Abstract +
VASCOVID is hybrid diffuse optical platform developed within the Horizon2020 project VASCOVID. The device combines time resolved near-infrared and diffuse correlation spectroscopy alongside pulse oximetry and an automatized tourniquet, for performing localized vascular occlusions. This device has been designed to enable fast transition to medical approvals process and documented in such a way to enable standardized multi-center clinical studies. Here we demonstrate its accuracy, precision and variability both in-vivo and on tissue mimicking phantom measurements.
12628-34
27 June 2023 • 17:00 - 17:15 CEST | Room 5 ICM Ground Floor
Session 8:
Advances in Instrumentation and Technology II
28 June 2023 • 08:30 - 10:00 CEST | Room 5 ICM Ground Floor
Session Chairs:
Ilias Tachtsidis, Univ. College London (United Kingdom), Laura Di Sieno, Politecnico di Milano (Italy)
12628-35
NearWave imager: the first entirely handheld real-time frequency-domain near-infrared spectroscopy imaging system
(Invited Paper)
28 June 2023 • 08:30 - 09:00 CEST | Room 5 ICM Ground Floor
Show Abstract +
We demonstrate the first entirely handheld frequency-domain near-infrared spectroscopy imager capable of displaying 2D images in real-time. The system provides real-time imaging and addresses many of the limitations of prior fdNIRS systems including system size, speed, and ease of use.
12628-36
Development and preliminary testing of a multi-wavelength wearable diffuse optical tomography system
28 June 2023 • 09:00 - 09:15 CEST | Room 5 ICM Ground Floor
Show Abstract +
We present a prototype wearable multi-wavelength high-density diffuse optical tomography (HD-DOT) neuroimaging system to simultaneously measure brain oxygenation and metabolism. An array of hexagonal imaging modules has been designed to extract changes in concentration of oxyhaemoglobin (HbO), deoxyhaemoglobin (HbR) and cytochrome-c-oxidase (CCO). Each imaging module contains four detectors and a single LED module emitting at five discrete wavelengths. Dynamic phantom experiments with blood and yeast were designed to validate the system against the current gold standard technique (broadband NIRS or bNIRS). The peak changes in concentration as measured by the HD-DOT system were: ∆HbO = -5.9μM, ∆HbR = +11.3μM and ∆oxCCO = -2.1μM, and the changes measured by the bNIRS system were: ∆HbO = -14.6μM, ∆HbR = +16.9μM and ∆oxCCO = -0.6μM.
12628-37
On demand | Presented live 28 June 2023
Show Abstract +
Near-infrared optical tomography (NIROT) is a non-invasive imaging technique based on diffuse propagation of light in turbid media. It has high sensitivity to tissue oxygenation, which is a vital biomarker. NIROT enables one to quantify and image oxygenation at a bed-side in clinics, thus complementing other imaging modalities. Time-domain (TD) NIROT systems benefit from time-of-flight (ToF) information, but are often affected by relatively low signal-to-noise ratio and long acquisition time. However, fast acquisition is needed for in vivo assessment of oxygenation. In this work we present a time-multiplexing approach which enables multiple-fold faster acquisition with high SNR, suitable for various ToF applications, including NIROT. We combine it with hybrid convolutional neural-network (hCNN) -enhanced reconstruction to achieve an impressive 11-fold increase in acquisition speed.
12628-38
28 June 2023 • 09:30 - 09:45 CEST | Room 5 ICM Ground Floor
Show Abstract +
We developed and applied parallel interferometric near-infrared spectroscopy (πNIRS) for rapid cerebral blood flow and absorption monitoring. By operating ~100-500x faster than competing optical techniques, we can monitor prefrontal cortex activation in humans in vivo
12628-39
On demand | Presented live 28 June 2023
Show Abstract +
Invasion depth information of cancer in early stages, which is difficult to obtain accurately using current biological imaging technologies, is very beneficial for cancer diagnosis. The circularly polarized light scattering method can provide depth profiles by varying the incident or detection angles as well as wavelengths of circularly polarized light. This paper reports the results of Monte Carlo simulations and experiments to demonstrate cancer depth estimation using this technique.
Break
Coffee Break 10:00 - 10:30
Session 9:
Advances in Instrumentation and Technology III
28 June 2023 • 10:30 - 11:45 CEST | Room 5 ICM Ground Floor
Session Chair:
Davide Contini, Politecnico di Milano (Italy)
12628-40
On demand | Presented live 28 June 2023
Show Abstract +
We present the application to time-domain diffuse optics of a device composed of 8x256 CMOS SPAD array with 256 7-bit time-to-digital converters. Thanks to its structure and despite the limitation on the maximum repetition rate of the laser (2 MHz), it has been demonstrated to be suitable for fast acquisitions (10 ms) provided that a high photon count-rate is used and pile-up distortion is corrected. We demonstrate that high penetration depth (>30 mm) and good linearity in absorption coefficient retrieval can be achieved. Finally, we were able to clearly record the heart beat in a resting state forehead measurement.
12628-41
On demand | Presented live 28 June 2023
Show Abstract +
Time domain diffuse correlation spectroscopy (td-DCS), has been proposed as a method that can increase the sensitivity of DCS for detecting blood flow index (BFI) in deep tissue. Several important parameters including the instrument response function (IRF), gate start time, gate width, and source-detector separation (SDS) must be taken into consideration. In our study, we characterized td-DCS system at three different SDS values and assessed each SDS's ability to detect dynamic changes of blood flow caused by moving red blood cells during cuff occlusion.
12628-42
28 June 2023 • 11:00 - 11:15 CEST | Room 5 ICM Ground Floor
Show Abstract +
Parallelized diffuse correlation spectroscopy (PDCS) is an emerging technology to measure flow based on decorrelating speckle analysis. PDCS relies on the use of an array of single-photon avalanche diodes (SPADs) to increase the signal-to-noise ratio (SNR) by measuring multiple speckles in parallel. Recently, a novel 1/4-megapixel SPAD camera was developed that can boost the SNR by a factor of 500, compared to conventional DCS. Here, we present how this label-free optical technology can measure blood flow in the human brain at unprecedented tissue depth and sensitivities.
12628-43
On demand | Presented live 28 June 2023
Show Abstract +
Bioresorbable materials have gained interest for implantable optical components such as fibers for medical devices and have been demonstrated as suitable to perform diffuse optical measurements. In this work, we demonstrate interstitial, broadband Time Domain Diffuse Optical Spectroscopy (TD-DOS) measurements using bioresorbable fibers by employing a Single Photon Avalanche Diode (SPAD) operated in an ultrafast time-gate mode for detection. Using tissue equivalent liquid phantoms, we test the system absorption linearity as per the MEDPHOT protocol and demonstrate the scattering independent absorption retrieval of the water spectrum in the 600-920 nm range. Consequently, we also attempt to measure the spectral changes due to the presence of meat inclusion in a tissue equivalent liquid phantom.
12628-44
On demand | Presented live 28 June 2023
Show Abstract +
Optical imaging in the second near-infrared (NIR-II, 1000–1700 nm) is suitable for visualizing tumor vascular imaging and targeting bone structures in small animals. In this study, we developed a novel three-dimensional (3D) NIR-II fluorescence rotational stereo imaging system for conducting 3D tumor vascular imaging and bone imaging in mice with only one NIR-II camera and a rotational stereo vision technique. Our system utilizes a 3D blood vessel reconstruction algorithm to present high-resolution 3D blood vessel maps and skeletal systems through two camera views. This technique allows for the visualization of bone structure and the identification of metabolic diseases such as osteoporosis. We validated the system with custom-made 3D printing phantoms and 4T1 tumor-bearing mice, demonstrating the ability to accurately recover the tumor blood vessels and bones with an imaging depth of 5 mm, an image resolution of 0.15 mm, and a depth resolution of 0.35 mm.
Break
Lunch Break 11:45 - 13:30
Session 10:
Advances in Instrumentation and Technology IV
28 June 2023 • 13:30 - 15:00 CEST | Room 5 ICM Ground Floor
Session Chairs:
Adam T. Eggebrecht, Washington Univ. School of Medicine in St. Louis (United States), Sanathana Konugolu Venkata Sekar, Irish Photonic Integration Ctr. (IPIC) (Ireland)
12628-45
Short and long-term photostability of 3D printed fluorescent phantoms for near-infrared diffuse optical imaging
(Invited Paper)
On demand | Presented live 28 June 2023
Show Abstract +
We have successfully printed an anatomically shaped hand model with properties similar to in vivo investigations with a fluorescence hand imager using indocyanine green (ICG). By adding the fluorescent dye Lumogen IR 765, titanium dioxide powder and black ink to a 3D printing methacrylate photopolymer we realized phantoms with physiologically relevant absorption and reduced scattering coefficients as well as fluorescence properties similar to the widely applied contrast agent ICG. The phantoms show an excellent long-term photostability making them well suited for device performance monitoring and comparison. In contrast, fluorescence of phantoms printed with ICG continuously decreases over time.
12628-46
On demand | Presented live 28 June 2023
Show Abstract +
We introduce a novel cerebral perfusion phantom to calibrate laser speckle imaging systems for small animal brain imaging. A method based on Hele-Shaw cell technique is used to create fractal like structures which serves as the mould for the phantom making. The structure is casted to create micro channels in PDMS phantoms which is found to closely mimic the structure of superficial cerebral blood vessels in small animals. The proposed method has the potential to fabricate optically and anatomically accurate cerebral perfusion phantom using a quick and inexpensive fabrication technique suitable for blood flow imaging studies
12628-47
On demand | Presented live 28 June 2023
Show Abstract +
The HyperProbe consortium started on October1, 2022: a EIC-funded, 5-years project that aims at delivering the technological capacity, based on innovative hyperspectral imaging, to shape the future of neuronavigation in brain surgery, by centering it on real-time, quantitative monitoring of brain activity and functions, with and without cerebral stimulation, to better assist and guide neurosurgeons. A consortium made of research groups and industries from Italy, France, Austria, Germany and the UK, in the HyperProbe project we will design, develop and validate clinically a novel, all-optical, multifunctional imaging device that can lead such transformation and advancement by providing exhaustive characterisation of the morpho-chemical features of cerebral tissue during surgery. Such a device can then allow surgeons to access unprecedented functional, structural and pathological information that can improve patient treatment during neurosurgical practices, such as glioma resection.
12628-48
On demand | Presented live 28 June 2023
Show Abstract +
Scanning Laser Optical Tomography (SLOT) is an imaging technique used to acquire three-dimensional data from biological and other samples on a mesoscale. With this technology, a set of two-dimensional images is processed into volume information. Different contrast mechanisms can be used, depending on the application.
In order to increase the level of automation and reduce motion artifacts, we present two new methods. The first is an automated sample detection and tracking, which makes any manual sample alignment obsolete. The second is an automated pre-processing algorithm which corrects occurring motion artifacts to increase the accuracy of the tomographic reconstruction.
12628-49
On demand | Presented live 28 June 2023
Show Abstract +
Transabdominal fetal pulse oximetry can be used to improve the maternal and fetal outcome during the delivery by measuring the fetal arterial oxygen saturation (SpO2). The feasibility of this application depends on if the change in fetal absorption is detectable. In this study, we performed photon simulation on a 3D model with anatomy of pregnancy. We found that with long source-detector distance, the measurement sensitivity to the fetus is small, but is it still possible to reconstruct the change in fetal absorption. These results could guide us towards better hardware design for measuring the fetal SpO2.
Break
Break 15:00 - 15:30
Session 11:
Theory, Algorithms and Modeling II
28 June 2023 • 15:30 - 16:45 CEST | Room 5 ICM Ground Floor
Session Chairs:
Davide Contini, Politecnico di Milano (Italy), Adam Liebert, Nalecz Institute of Biocybernetics and Biomedical Engineering PAN (Poland)
12628-50
On demand | Presented live 28 June 2023
Show Abstract +
Recently, deep learning has gained popularity as a reconstruction method to solve diffuse optical tomography. However, despite its success, previous studies only reconstructed semi-homogeneous breasts with an absorption coefficient resolution of 2e-3 mm ^(-1). In this paper, we propose a novel preprocessing method that considers the spatial correlations between different measurements to improve the reconstruction accuracy. Our algorithm is applied on a non-homogeneous breast phantom with absorption coefficient resolution of 5e-7 mm ^(-1) to reconstruct its optical properties. The proposed method is able to reduce the RMSE by more than 70% (0.44 to 0.11) and increase the contrast ratio by almost an order of magnitude (0.09 to 0.79).
12628-51
On demand | Presented live 28 June 2023
Show Abstract +
The spherical harmonics methods (classical and modified) can be used to solve the radiative transport equation in series form. However, the evaluation of the truncated series for the angular radiance near sources or boundaries is known to be a difficult or partly an impossible task.
In this conference paper, we report on a hybrid $P_N$-method which enables the evaluation of the angle-resolved radiance at the boundary of an anisotropically scattering medium.
The number of spherical harmonics required under the use of the hybrid model is reduced significantly compared with the classical or modified spherical harmonics method.
12628-52
28 June 2023 • 16:00 - 16:15 CEST | Room 5 ICM Ground Floor
12628-53
On demand | Presented live 28 June 2023
12628-96
On demand | Presented live 28 June 2023
Show Abstract +
Phantoms that accurately simulate in-vivo tissue properties are essential for the advancement of medical imaging methods. In this paper, we propose a novel approach to develop a fast and tunable dynamical phantom that mimics in-vivo blood flow, based on stochastic differential equations (SDE) and piezoelectric actuators. We validate the phantom using in-vivo human blood flow studies.
Program Committee
Washington Univ. School of Medicine in St. Louis (United States)
Program Committee
National Institute of Advanced Industrial Science and Technology (Japan)
Program Committee
Nalecz Institute of Biocybernetics and Biomedical Engineering PAN (Poland)
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