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- Front Matter: Volume 10820
- Photon Therapeutics II
- Biomedical Spectroscopy for Diagnostics
- Advanced Optical Techniques for Diagnostics I
- Advanced Optical Techniques for Diagnostics II
- Poster Session
Front Matter: Volume 10820
Front Matter: Volume 10820
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This PDF file contains the front matter associated with SPIE Proceedings Volume 10820, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.
Photon Therapeutics II
Compare the therapeutic effectiveness of photodynamic therapy with 980 nm laser on cervical intraepithelial neoplasia
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Aim: Cervical intraepithelial neoplasia (CIN) is the precursor of invasive cervical cancer and associated with human papilloma virus (HPV) infection. Standard treatment is conization and may be associated with subsequent pregnancy complications. Laser with wavelength of 980 nm is a treatment choice that can minimize the volume defect of the cervix. Photodynamic therapy (PDT) could targeted destroy the infective tissue and may be an interesting and safety alternative. The aim of this prospective unmatched-cohort study was therefore to compare the therapeutic effectiveness of PDT with 980 nm laser for CIN. Methods: 50 subjects consisted of CIN 1-2 patients treated at the present hospital. 30 patients were treated with PDT and 20 with 980 nm laser. The PDT procedure was irradiation with 630 nm laser (100 mW/cm2, 20 min) 72 h after intravenous injection of Hematoporphyrin derivative (3 mg/kg). 980 nm laser procedure was irradiation cervix with 10 W laser till color of coagulation tissue becoming gray. The cure standard of CIN was that pathological examination or TCT was normal, and HPV clearance rate were observed 3 month later. Results: 27 of the 30 patients (90%) in PDT group and 17 of the 20 patients (85%) in 980 nm laser group were cured. 18 of the 28 patients (64.3%) in PDT group and 11 of the 19 patients (57.9%) in 980 nm laser group HPV test was negative. There were no significant differences in cure rate and HPV clearance rate between PDT and 980 nm laser groups. Conclusions: PDT have same therapeutic effectiveness to 980 nm laser on CIN patients.
Time dependence of myocardial cell necrosis during photodynamic therapy with various photosensitizer contact time
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We studied how the photosensitizer contact time affects the myocardial necrosis time during photodynamic therapy under a confocal microscopic system. Electrical conduction block by photodynamic reaction would be utilized as new catheter ablation for tachyarrhythmia to reduce complications. Photodynamic therapy with a short drug-light interval, which induces the oxidation mainly on the cell membrane is profitable to induce immediate myocardial cell necrosis. The necessary time to induce necrosis is important in the catheter ablation since the real-time electrocardiogram diagnosis is used to judge the treatment effect in clinical. The photosensitizer distribution changes from moment to moment during the therapy in vivo. It is necessary to investigate the time dependence of myocardial cell necrosis with various photosensitizer contact time in vitro. We measured the intracellular Ca2+ using fluo-4 AM during and after the photosensitization reaction. Talaporfin sodium was used as the photosensitizer, a CW red diode laser of 664 nm in wavelength was used for the photosensitizer excitation. Irradiance was 120 mW/cm2 . The necrosis occurrence time was analyzed as the sufficient intracellular Ca2+ decrease after the membrane rupture. The photosensitizer contact time was varied up to 60 min. The necessary time for the myocardial cell necrosis decreased with photosensitizer contact time increasing and the necessary time for the myocardial cell necrosis reached a minimum value of 150 s when photosensitizer contact time was 15 min. After 15 min of photosensitizer contact time, the necessary time for the myocardial cell necrosis increased as photosensitizer contact time increased.
Biomedical Spectroscopy for Diagnostics
Comparative study between diagnostic mediums: human tissue and saliva for oral cancer detection using Stokes shift spectroscopy
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A comparative study has been accomplished between diagnostic mediums: human oral tissue and saliva for oral cancer detection on three groups: oral squamous cell carcinoma (OSCC), dysplastic, and control (normal) by using Stokes shift (SS) spectroscopy (SSS) at ▵λ of 120 nm, which is the Stokes shift of nicotinamide adenine dinucleotide (NADH). SS spectra obtained from tissue and saliva consist of major bands of collagen, tryptophan, NADH and minor bands of flavin adenine dinucleotide (FAD) and porphyrin. Principal component analysis (PCA) has been performed on the data sets of SS spectra for discrimination by dimension reduction. Linear discriminant analysis (LDA) has been applied on the PC scores to compute linear discriminant (LD) scores. Kernel probability density functions of LD scores are plotted to show how LD scores of each group are separated from one another. LD scores for oral tissue differentiates OSCC to normal, dysplasia to normal, and OSCC to dysplasia with sensitivities 100 %, 85 %, 94 % and specificities 88 %, 88 %, 89 % with the accuracy of 95 %, 87 % and 92 %. On the other hand for saliva, it differentiates respective groups with sensitivities 91 %, 82 %, 91 % and specificities 100 %, 88 %, 82 % with the accuracy of 95 %, 85 % and 87 %. Obtained results with human saliva are as prominent as oral tissue and we conclude that it may be used as a substitute diagnostic medium. In addition SS spectroscopy instead of fluorescence spectroscopy at 120 nm shift appears to be an important tool for in vivo detection of early oral cancer.
Advanced Optical Techniques for Diagnostics I
Detection of various Thrombin concentrations using etched fiber Bragg gratings functionalized with DNA aptamer
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The response of etched fiber Bragg grating (EFBG) functionalized with 29-mer DNA aptamer to the different concentrations of Thrombin protein has been investigated. Etched FBGs are an efficient technology for detection of refractive index, and have been demonstrated also for biosensors applications. EFBGs have a simpler manufacturing approach comparing to other methodologies and are based on a low-cost device; their fabrication can be achieved by simple chemical etching, without requiring fusion splicing. During the test we assessed its feasibility for small variations of thrombin concentrations (10μg/ml, 20μg/ml, 40μg/ml and 80μg/ml). In particular, we performed experiments of chemical etching with hydrofluoric acid, which progressively depletes the fiber cladding exposing the core to the outer medium. Additionally, unstriped not etched FBGs were also used as a control for temperature pattern compensation. Before functionalization, EFBG was calibrated with different sucrose and ethanol solutions that validated the sensitivity to refractive index change. EFBG was further silanized with 3-Aminopropyl-triethoxysilane (APTES) in order to immobilize Thrombin binding aptamer on the silica surface of the fiber. The change of Bragg wavelength when functionalized EFBG is exposed to different concentrations of Thrombin using Micron Optics Hyperion si255-x55 sensing system was demonstrated. A small yet detectable sensitivity (several tens of nanomolars) even between small protein variations allows hypothesizing a future use of this kind of functionalized fiber for biosensor development.
The influence of bilirubin and creatinine on the refractive index of whole blood in terahertz frequency range: a qualitative analysis
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The glucose level of blood can be obtained by terahertz time-domain spectroscopy using refractive index measurement method. The detected refractive indices vary from person to person since the impact of bilirubin and creatinine wasn’t considered. 14 human blood samples were tested using terahertz time-domain spectroscopy. The experiment results show that under the certain concentration of glucose, the refractive index of blood decreases with the increase of bilirubin and creatinine concentration, and thus the concentration of other blood components may also influence on the refractive index of blood. The feasibility of using terahertz time-domain spectroscopy to determine the level of glucose, bilirubin and creatinine qualitatively and quantitatively is provided.
Quantitative single-exposure laser speckle contrast imaging
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Laser speckle contrast imaging (LSCI) is a well-established blood flow imaging technique, through the computed whole field contrast map. Though LSCI offers high spatial and temporal resolution, accurate quantification of blood flow remains a challenge. In this paper, we demonstrate a single exposure system, introducing a modified velocity computing approach incorporating the effects of scattering events and other experimental parameters to result in a relatively inexpensive LSCI system with near real time results. Parameters like vessel dimension and concentration of scattering centers are cumulatively represented by defining the number of scattering events in the region of interest (ROI). The number of scattering events is considered along with the decorrelation time in deducing flow velocity. We present a modified equation for velocity computation incorporating the effects of scattering centers. This work attempts to bring consistency in flow velocity calculation across different samples to achieve a robust single exposure LSCI system. The LSCI setup was calibrated based on a system dependent constant, which was found to be a linear function of flow velocity, to predict velocity quantitatively. We present the results of the developed system on standard micron-sized flow channels.
Smart dental detector
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Smart dental detector uses UV LED light source with the wavelength of 405nm to stimulate auto-fluorescence of teeth and FH8610 camera is applied for fluorescence imaging. Then the images can be transferred to mobile phone through WIFI wireless transmission. According to those images, doctors can diagnose caries easily at the early stage of tooth demineralization. So far, more than 300 dentists have used it to diagnose tooth diseases in China. The new technology of diagnosing caries is consistent with traditional diagnosis results. In addition, smart dental detector is an effective and portable device and the artificial intelligence (AI) algorithm is utilized to realize auto-classification.
Advanced Optical Techniques for Diagnostics II
Calcified plaque segmentation of intracoronary optical coherence tomography images based on LBF
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The segmentation of the intracoronary optical coherence tomography (IVOCT) images is the basis of the plaque assessment. Calcified plaque is one of the main thrombus plaques. Accurate segmentation of calcified plaque is important to the plaque feature analysis, vulnerable plaque recognition and further coronary disease diagnosis. Based on the knowledge of imaging processing, the inner boundary of calcified plaques is clear, but the outer boundary is hard to identify because of the weak edge. This paper proposed an algorithm about calcified plaque segmentation for IVOCT. Taking the segmented vessel wall by using dynamic threshold as the region of interest, the location of calcified plaque was determined by K-means clustering to obtain the inner edge. The Local Binary Fitting (LBF) active contour model is used to solve the problem of weak edge to clarify the outer edge. Then the distribution of superficial calcification can be evaluated. Ten coronary images with typical plaques from 3 patients in our experiment were used to taking the segmentation. The processing results were compared with the clinician manual segmentation. It is indicated that the proposed algorithm could segment the plaque regions accurately. This work hopefully can be used for automatic processing the serials of IVOCT images to reduce subjectivity and divergence between different clinician and contribute to the diagnosis and treatment of coronary artery disease from IVOCT.
In vivo measurement of retinal neurovascular changes with transcorneal electrical stimulation using optical coherence tomography
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Transcorneal electrical stimulation (TES), which as a noninvasive approach of retinal electrical stimulation, can activate releasing of neurotrophic factors and regenerate injured retinal neurons, has become a potential therapeutic method for retinal diseases. However, the mechanism of TES on the regeneration of retinal neurons has not been completely determined. The purpose of this study was to explore how the depth-resolved intrinsic optical signals (IOSs) and blood flow in cat retina change with TES. In the experiments, the cat retinae were imaged by our custom-designed spectraldomain OCT with a central wavelength of 840nm. OCT scanning and TES were synchronized so as to record images of retina at pre-, during and post-stimulation period, respectively. In each period, the IOSs were then extracted in structure images by registration and segmentation algorithms. And the blood flow was extracted in phase contrast images derived by phase-resolved Doppler OCT method including bulk motion compensation and phase unwrapping. Based on our preliminary results on 5 eyes of 4 cats, we found a significant increase of both positive and negative IOSs in each layer during and after TES compared to those of pre-stimulation and sham stimulation, while the changes of average blood flow before, during and 6 seconds after TES were not obvious. The preliminary results provide experimental data of neurovascular alterations under TES, which will benefit the study of the therapeutic mechanism of TES. But complete understanding of neurovascular response to TES should be further investigated.
Segmentation of diabetic macular edema for retinal OCT images
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Optical coherence tomography (OCT) is becoming one of the most important detection modalities for fast and noninvasive assessment of ophthalmological diseases. Diabetic macular edema (DME) is one of the important reasons leads to blindness. Its pathological features are mainly manifested in the accumulation of fluid in the retina. An automated method is proposed to identify and quantify the volume of cystoid macular edema in Spectral Domain OCT (SD-OCT) images. In the first stage of preprocessing, we balance the apparent signal-to-noise of each retinal OCT image. Because the signal-to-noise of OCT images is variable from patient to patient, and balance of the signal-to-noise ensures consistent segmentation of cystoid fluid. Speckle noise is the main reason leads to quality degrading in OCT images. The denoising method should be efficient for the noise suppression, and the edge information can be preserved at the same time. Then we used the anisotropic diffusion filter to suppress shot noise. The intensity inhomogeneity in OCT images may lead to false detection in the further segmentation work. Then we used the gamma transformation to change the brightness, which eliminates the effect availably. In the second stage of segmentation, we solve the problem of segmentation effectively by the improved level set method and calculated the area of edema area, which provides quantitative analytic tools for clinical diagnosis and therapy. Finally, the proposed method was evaluated on 15 SD-OCT retinal images from DME adults. Leave-one-out evaluation resulted in a precision, sensitivity and dice similarity coefficient (DSC) of 81.12%, 86.90% and 80.05%, respectively.
Poster Session
Vessel extraction from angiography image using dictionary inpainting
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Due to the complex background and varying scanning conditions, extracting the vessel structure from the rotational angiography (RA) image is challenging. Various methods have been proposed for binary vessel segmentation with no gray level information which is essentially for diagnosis. A new method based on background inpainting and image subtraction is introduced in this paper. Instead of providing binary segmentation result, the proposed method estimates the background caused by surrounding tissues, and the vessel structure with gray level is obtained via image subtraction. The experiments verify that the proposed method works well for clinical sequences with different scanning conditions.
Measuring temperature-induced effective attenuation coefficient spectra of biological tissue based on diffuse reflection spectroscopy
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In the non-invasive blood glucose measurement based on near-infrared spectroscopy, the glucose signal is very weak and easy to be disturbed. Tissue temperature fluctuation is a primary disturbance source, since it would greatly affect the accuracy of blood glucose concentration results. We present a method called differential diffuse reflection spectroscopy, which makes a differential processing on the data from multiple source-detector distances (SDDs), and it can directly estimate the change in effective attenuation coefficient (EAC) of tissue. Using EAC spectra, we investigated the influence of temperature on the tissue spectra and then used a multivariable analysis of external parameters orthogonalization (EPO) to calibrate the spectra. The spectra of 1000-1800 nm caused by temperature and glucose are compared. Theoretical computing, Monte Carlo simulations and experiments were used to test this method. In conclusion, this proposed method using EAC spectrum to monitor the tissue change shows a promising application potential in non-invasive blood glucose measurement.
Monitoring of blood protein using double slot hybrid plasmonic waveguide
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The deterioration of environmental conditions decreases the quality of people lives permanently. The prime reason in mortality of people lives in industrial developing countries is disease related to blood circulation system. In this work, monitoring of blood protein i.e. fibrinogen is done by double slot hybrid plasmonic waveguide. The concentration of fibrinogen increases rapidly during various inflammatory processes. The fibrinogen is a type of protein which is found in blood coagulation system, which is the main factors of many cardiovascular diseases in human.
Antioxidant, anti-inflammatory, and immunostimulatory activity of polysaccharide from artemisiae argyi folium
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As the traditional Chinese medicine, artemisiae argyi folium has various functions such as analgesia, antitumor, and anti-hypertension. To study antioxidant activity in vitro and cell-based anti-inflammatory activity of artemisiae argyi folium polysaccharide (AAFP). The antioxidant activity of AAFP was investigated by ABTS+ • clearance rate, DPPH•clearance rate, • OH clearance rate and FRAP assays. The lipopolysaccharide-induced RAW264.7 cell inflammation model was established to assess its anti-inflammatory activity. The results showed that the AAFP had strong antioxidant activity and the IC50 on ABTS radicals, DPPH radicals, hydroxyl radicals, and the ferric reducing antioxidant power were 74.41, 268.5, 350.2μg/ml and the FRAP value was 163.5μg/ml. MTT experiments showed IC50 of AAFP was 441.5μg/ml. The quantitative polymerase chain reaction demonstrate the pro-inflammatory activity of AAFP. Immunological assay showed that AAFP significantly promoted lymphocyte proliferation. AAFP have huge potential to be developed as functional foods and medicines.
Determination of aloin in aloe extracts from different companies by HPLC-UV
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To give some foundation for quality standards of the aloe extracts, by studying the contents of the aloin in aloe extracts and evaluating scientifically the quality of the aloe extracts from different companies. The chromatographic separation was performed on a SunFire C18 column (250mm×4.6mm, 5 μm). The mobile phase comprised acetonitrile-water (25:75, V/V,) at a flow rate of 1.0 mL/min. The detection wavelength was set at 355nm. There was a great difference in the aloe extracts from different companies. There was a good linear relationship between peak area and the injection volume over the range of 2.5-20μL (R2 = 0.9992). The average spike recovery of the aloin was 99.62%, With a RSD of 1.20%(n=6). The contents of aloe extracts from different companies were 90.64-263.11mg/g. This method is simple, fast and the result is accurate and reliable and can be used for the determination of the aloin in aloe extracts.
Numerical analysis of optical super-resolution in a structure of quasi-Luneburg-sphere
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Luneburg-sphere (LS) is a spherically symmetric sphere with three-dimensional graded-refractive-index structure which can focus parallel beam to a perfect point on the sphere surface. Recent research shows that microsphere can generate super-resolution focusing beyond diffraction limit. Herein a quasi-Luneburg-lens can be used as an optically transparent microsphere for the super-resolution imaging. In this paper, the finite element model is used to investigate the optical properties of the Luneburg-lens. Our simulation results demonstrated that its focus size is below the conventional diffractive limit in the visible spectrum. An effective method of application of a quasiLuneburg-lens is proposed and discussed. Besides super-resolution imaging, Luneburg-lens have the potential applications in nanolithography, nanomedicine areas as well.
Effects of multiple factors on the photoacoustic detection of glucose based on artificial neural network
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In this paper, to study the effect of multiple factors on the photoacoustic detection of glucose, a Nd: YAG 532nm pumped optical parameters oscillator (OPO) pulsed laser induced photoacoustic detection system were established. The lateral model was used to capture the photoacoustic signals of glucose by using the ultrasonic transducer. The photoacoustic signals were averaged in 512 times. In the experiments, the photoacoustic experiments of different concentrations, temperatures, laser energies and flow velocities for glucose aqueous solutions were performed. Meanwhile, the effects of concentration, temperature, energy, flow velocity on the photoacoustic detection of glucose were investigated. Not only the relationships between the each factor and the photoacoustic detection of glucose were built, but also the coupled relationship between the multiple factors on the photoacoustic detection of glucose was also established by using the artificial neural network. In the artificial neural network, three levels neural network includes four input parameters and one output target was used. Prediction results show that the coupled relationship can better present the practical condition of glucose detection, which can offer the potential research value for the photoacoustic detection of diabetes mellitus.
Multiphoton imaging of gastric intestinal metaplasia
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Intestinal metaplasia has been widely considered as a precursor of gastric cancer, and early detection and accurate diagnosis will have important clinical significance. Therefore, multiphoton microscopy using two-photon excited fluorescence combined with second harmonic generation was used for investigating gastric intestinal metaplasia in this work, and imaging results showed that this microscope has the ability to directly differentiate this lesion in the absence of labels. This study highlights the potential of multiphoton microscopy as a diagnostic tool for label-freely identifying gastric intestinal metaplasia.
Testing of display color causing excitation in eye periphery creating nonlinear distortions of psychophysical response
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We used psychometric responses of phenomena as criteria – to study perception distortion strength in peripheral areas, while looking towards vertically falling round spots. Spots were objects peripherally projected in the eye, having periodical grey-colored (or red, green, blue) grating moving horizontally within the spot area. Such excitation creates psychophysical perception distortion; falling projected in the brain has slant – Shapiro and Lu effect (2010). We studied the phenomenon by comparing perceived slants of two falling balls viewed in opposite peripheral areas: a) reference object – uniform and neutrally grey, falling at a distinct angle; and b) textured object: falling vertically, with vertical stripe structure that moved along horizontal direction within the object area. Psychometric curves were built using 2ATC paradigm. Observers in Part I were naïve participants, who during one hour responded to series of events where the reference objects had a randomly selected slant of fall trajectory. Subjective equivalence point was determined at the centers of the sigmoidal fit of psychometric curves where abscise was a reference real slant. Mean (22 participants) illusionary slant of falling textured objects was α = 28±5 deg (for viewing directionality ≈8 deg; falling vertical speed 0.18 deg/sec, texture Michelson contrast 0.82, texture spatial frequency 0.42 cycles/deg, “spinning” speed 2 deg/sec). In Part II two observers repeated the experiments in similar viewing conditions each day for two weeks. Distinct decay of α was determined with exponential time constant of 11±2 days. Most surprisingly, the decay curves converge to zero values for supposed infinitive length of demonstrations. Preliminary discussion of the latter with illusion authors revealed coincidence of our results with author’s suggestions. As such learning effect has been detected, the observers in Part III compared two equiluminant striped falling balls in opposite viewing fields, but balls contained different color content. Here we find differences of the slant in perception, however these differences were statistically insignificant.
Cellular phase observations and measurements on red blood cells affected by lithium and lead ions with quantitative interferometric microscopy
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As an important marker in disease diagnosis, red blood cell morphology measurement is necessary in biological and medical fields. However, traditional setups as microscopes and cytometers cannot provide enough quantitative information in morphology detections. In order to capture tiny variations of red blood cells affected by metal ions in external environment, quantitative interferometric microscopy is applied: combining with phase retrieval and cell recognition, cellular phases as well as additional quantitative cellular parameters can be acquired automatically and accurately. The research proves that quantitative interferometric microscopy can be potentially applied in cellular observations and measurements for both biological and medical applications.
Digital field-of-view correction for dual-view transport-of-intensity equation-based quantitative microscopy
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As an ideal way for quantitative live cell imaging, dual view transport of intensity equation (TIE) method can provide both real time imaging, multi-mode observations, simple setup and large field of view (FoV). However, the image recorder installation error reduces the accuracy in both amplitude and phase retrievals, because of the inevitable FoV mismatch between the captured under- and over-focus intensities. In order to obtain higher accuracy amplitude and phase retrievals, the phase correlation based digital FoV correction is introduced into our method, rotation, scale and translation between the under- and over-focus images are compensated by the phase correlation based digital FoV correction. Measurements are implemented using standard sample detection and quantitative live cell imaging, proving that the proposed method can improve the accurate of the amplitude and phase computations.
High speed and large effective range autofocusing based on numerical wavefront propagation
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Autofocusing is widely used in microscopy since it provides sample details with high resolution and contrast. However, massive image recording along optical axis is often indispensable in classical autofocusing tactics, obviously decreasing autofocusing speed. To increase processing efficiency, we propose numerical wavefront propagation based autofocusing with high speed and large effective range. Firstly, quantitative sample phase is retrieved from multi-focal images according to transport of intensity equation with Gerchberg-Saxton algorithm. Then, various intensities along optical axis are numerically computed via wavefront propagation, thus focal position can be determined according to in-focus criterion. Finally, in-focus image is recorded via sample stage shifting. Since the proposed autofocusing approach can be easily integrated into commercial microscopes, additionally, it considerably reduces image captures as well as time consuming, we believe it can be adopted for rapid autofocusing in microscope.
Application of photodynamic fluorescence diagnosis in skin tumors
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Photodynamic fluorescence diagnosis（PDD）is a technology that use laser-induced fluorescence in the presence of photosensitizer to diagnose tumor. This application can help locate the extent of tumor and the edge of tumor lesion and is very important for the treatment of the tumor. PDD plays an important guiding role in accurately grasping the changes of photosensitizer information in the target tissue, understanding the progress of photodynamic therapy, and establishing a reasonable photodynamic therapy (PDT) program. A brief overview of the principles of fluorescence diagnostics is talked about here. And through experiments, it has obtained fluorescence before and after the treatment in several skin tumors, such as basal cell carcinoma (BCC) and Extramammary Paget's disease.
Quantitative measurements of gastric cancers based on spectrum-resolved multiphoton imaging
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Targeted therapy is crucial to improving the prognosis of gastric cancer and thus decreasing its mortality. The premise of designing targeted therapy strategy is the identification and subtype classification of malignant gastric lesions. Spectrum-resolved multiphoton microscopy (SMPM) is capable of providing not only structural, but also biochemical information at subcellular level. Comparing with conventional techniques that generally focus on qualitative morphological characterizing of gastric mucosa, this multidimensional imaging technique may provide more powerful diagnostic capabilities. However, its full potential value has not been extensively evaluated in clinical settings. Here, we performed an investigation on human gastric cancers based on label-free SMPM imaging of fresh tissue specimens of normal gastric mucosa, intestinal-type adenocarcinoma, and neuroendocrine carcinoma. By extracting emission spectral information of endogenous fluorophores, the three-dimensional subcellular histology and biochemical components of gastric mucosa are revealed. Based on these clues, the sub-structures of gastric mucosa, including surface epithelium, interstitial tissue of lamina propria, and gastric pit, are clearly identified. Furthermore, qualitative and quantitative indicators based on the SMPM signals of gastric mucosa were created, which are found to have the potential to discriminate normal gastric mucosa and different types of gastric cancers. This study fills the knowledge gap of human malignant gastric lesions under SMPM imaging and may shed new light on the diagnosis and classification of gastric cancers. With advances in multiphoton endoscopy, the SMPM has the potential to be developed into a noninvasive, label-free, real-time histological and functional diagnosis instrument in the future.
Detection of oligomerization of Epstein-Barr virus oncoprotein LMP1 by FRET-based probes
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In this study, two FRET-based probes are constructed to research oligomerization of Epstein-Barr virus Oncoprotein LMP1 in live cells. The images of wide-field fluorescence microscopy display that the majority of two LMP1-associated probes co-localized in internal perinuclear membranes. Furthermore, the fluorescence spectra of single cell co-expressed two probes indicated that the ratio of two emission peaks is around one, and the fluorescence spectra changed insignificantly during an hour observation. These findings indicated that LMP1/LMP1 interacted stably in live cells.
Combining EMD with ICA for photoacoustic imaging denoising
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Photoacoustic (PA) tomography is an imaging technology that reconstructs the distribution of light absorption in tissue by photoacoustic signals. In recent years, PA tomography has been widely used in anatomical, functional and molecular imaging. However, one of the great challenges is that the efficiency of light to sound conversion is very low due to photoacoustic effect, resulting in low signal-to-noise ratio (SNR) of photoacoustic signal, especially for deep tissue imaging. Conventional approach to enhance the SNR of photoacoustic signal is data averaging, which is quite time-consuming. In the absence of signal fidelity and imaging speed, an algorithm of using empirical mode decomposition (EMD) and independent component analysis (ICA) de-noising in photoacoustic tomography is proposed. Firstly, the photoacoustic signal is decomposed into a series of intrinsic mode functions (IMFs) with EMD. Each IMF is equivalent to an independent signal. Then, some IMFs are selected to construct the virtual noise channel according to the correlation between IMF and original photoacoustic signal. Finally, the original photoacoustic signal and the virtual noise channel are regarded as the input data for ICA. ICA extracts useful photoacoustic signals from artificially constructed multidimensional data. The de-noised results are compared with that the wavelet de-noising method and bandpass filtering method. The enhancement of the SNR of the photoacoustic signal and the contrast of the reconstructed image have been well demonstrated. The proposed method provides the potential to develop real-time low-cost PA tomography system with low-power laser source and poor PA signal’s SNR.
Quantitative FRET measurement of the interaction of A1 adenosine receptors and A2A adenosine receptors in living cell
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Adenosine plays important roles in the pain signal transduction by activating adenosine receptors of two subtypes of A1 and A2A. In this study, FRET system based independent emission -spectral spectral spectral unmixing method (Iem-spFRET) was set up and used to measure the energy transfer from A1R to A2AR. The energy transfer efficiency calculated by Iem-spFRET is about 17.44%. All the above date and results demonstrate that FRET with special designed fluorescence proteins could be used to investigate the interaction between adenosine receptors.
In-line taper fiber-optic interferometer and FBG for label-free detection of cancer biomarker
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A taper interferometer embedded in fiber Bragg grating (FBG) is proposed and experimentally demonstrated for labelfree detection of breast cancer biomarker (HER2). The tapered fiber-optic interferometer sensor is extremely sensitive to ambient refractive index (RI) and the resonant wavelength of FBG is essentially insensitive to the RI variation. The FBG can be applied as a temperature thermometer, which monitoring the undesired drifts due to its independent response to the temperature. The label-free bio-recognition scheme is achieved by the covalent immobilization method for conjugation with HER2 antibody to achieve target biomarker specific detection. The proposed sensor presents a low limit-of-detection (LOD) of 5 ng/mL, providing a platform for the application in early diagnosis on the breast cancer.
Label-free multiphoton microscopy for ex vivo brain imaging: toward assisting pathologic diagnosis
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Standard histopathology is well accepted as the gold standard for the diagnosis a wide range of diseases. Despite continuing advances in tissue staining automation, typical histological processing such as formalin-fixed paraffin-embedded are also labour- and time-intensive for treatment decisions in intraoperative histopathologic diagnosis. Multiphoton microscopy (MPM), based on second harmonic generation (SHG) and two-photon excited fluorescence (TPEF), can be a versatile tool that enables label-free mapping of endogenous fluorophores within a fresh specimen, which provides pathology-like images with cellular and subcellular details. Here, we describe the use of label-free MPM for visualizing rat and human ex vivo brain tissue without tissue fixation, processing, and staining. Moreover, MPM is able to identify 6 types of cells in rat cerebrum and cerebellum, including cortical neurons, glia cells, Purkinje cells, pyramidal neurons and granule neurons in hippocampus, as well as epithelial cells in lateral ventricle. In addition, we further demonstrate that MPM can provide definitive pathological features in cerebral ischemia and focal cortical dysplasia (FCD) for assisting pathologic diagnosis. Our work establishes the methodology and augments the diagnostic accuracy of traditional frozen section histopathology. With the development of the miniature two-photon microscope, MPM will show more potential as a practical clinical tool for providing intraoperative reference image guidance of resection in neurosurgery.
STED super-resolution imaging of mitochondria in live cells
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A series of new fluorescent probes were developed to carry out live cell super-resolution imaging with low STED laser power or suitable STORM working conditions. And STED-FLIM imaging of microtubules labeled with ATTO647N inside HeLa cells and the mitosis process was obtained, which provides new insight into the cell structure and functions.Finally, stochastic optical reconstruction microscopy (STORM) super-resolution imaging of mitochondrial membrane in live HeLa cells was obtained by the implementation of new fluorescent probes, improved imaging system and optimized single molecule localization algorithm. This provided an important tool and strategy for studying dynamic events and complex functions in living cells.
Modified optical coefficient measurements using a single high-NA fiber with detection parameter changes at a tip
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To avoid the instability of an optical coefficient measurement using sliced tissue preparation, an attenuation coefficient measurement by puncturing an optical fiber in bulk tissue have been reported. We proposed a modified puncturing method to obtain an absorption coefficient and scattering coefficient by increasing optical information. We used the light intensity measurement through a single high-NA fiber puncturing into an optically thick bulk tissue varying detection parameters, the depth and field of view (FOV), at the tip. The light intensity measurement and ray trace calculation using the Monte Carlo method (inverse or normal) were employed. We constructed the measurement system which can change the FOV at the fiber tip inside the bulk tissue using the variable aperture outside the bulk tissue. A 200 μmΦ NA:0.5 fiber installed in a 21G needle was punctured down to surface of the bulk tissue to measure light intensity in the bulk tissue. Using homogeneous optical model solution, the accuracy about attenuation coefficients of the constructed experimental system was confirmed. The error in the attenuation coefficient was up to 1.4%. We demonstrated the optical coefficient measurement of porcine myocardium using the proposed method. To fit dependence of the measured attenuation coefficients on FOV, we decided that the absorption coefficient, the scattering coefficient, and anisotropic parameter were 0.2 mm-1, 10 mm-1, and 0.96, respectively. We proposed modified puncturing optical coefficient measurement varying depth and FOV. We demonstrated its usefulness on myocardium.
Photoacoustic classification of tumor malignancy based on support vector machine
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Accurate diagnosis of malignancy tumor in early stage is great significance to achieve high curability, which could improve survival rate in this stage. Precise classification to differentiate malignancy of tumors is favourable to reduce cost in treatment when there is no obvious features in radiology diagnose in early phase. Photoacoustic tomography (PAT) is a burgeoning new imaging modality, which combines optical contrast and ultrasound penetrating in deep medium. However, it has not been fully exploited on the capability of PAT to discriminate tumor’s malignancy. In this paper, a multistatic classification approach in PAT is proposed, which could discriminate malignant/benign tumors based on its morphological feature in clinical diagnosis that tumors usually show different shape irregularity compared with healthy tissue. The multistatic photoacoustic waves were used to extract two different features to differentiate the two types of tumors with high accuracy (<90%) in three different scenarios using Support Vector Machines (SVM). In addition, two conventional PAT image reconstructing algorithms are also performed to reconstruct images as a comparative study, which unfortunately cannot differentiate their malignancy precisely because of limited detector bandwidth and severe acoustic distortion. We performed the feasibility study in this paper with both simulation and experimental results, which shows that the proposed multistatic photoacoustic classification method to distinguish between malignant and benign tumors works well, and could be easily applied for state-of-art array-based PAT system to ameliorate the diagnostic accuracy.
Deep learning for super-resolution localization microscopy
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Super-resolution localization microscopy techniques (e.g., STORM or PALM), breaks the optics diffraction limit, making possible the observation of sub-cellular structures in vivo. However, long acquisition time is required to maintain a desired high spatial resolution. To overcome the limitation, an effective method is to increase the density of activated emitters in each frame. The high-density emitters will cause them to overlap, which makes it difficult to accurately resolve each emitter location. Although some methods have been proposed to identify the overlapped emitters, these methods are computationally intensive and parameter dependent. To address these problems, in this paper, we proposed a novel method based on convolutional neural networks (CNN) for super-resolution localization microscopy, termed as DL-SRLM. DL-SRLM is capable of learning the nonlinear mapping between a camera frame (i.e., the experimentally acquired low-resolution image) and the true locations of emitters in the corresponding image region (i.e., the recovered super-resolution image). As a result, the method provides the possibility to faster resolve the high-density emitters, without requiring the parameters. To evaluate the performance of DL-SRLM, a series of simulations with varying emitter densities, signal-to-noise ratios (SNRs), and point spread functions (PSFs) were performed. The results show that DL-SRLM can accurately resolve the locations of high-density emitters, even if when the raw measurement data contained noise or was generated by using inaccurate PSF. In addition, DL-SRLM greatly improve the computational speed (~ 15 ms/frame) compared with the current methods while avoiding the effect of the parameters on the super-resolution imaging performance.
3D measurement of collagen directional variance in ovarian cancer by multiphoton microscopy
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Ovarian cancer accounts for the highest mortality rate among all gynecologic cancers. Current diagnosis methods of ovarian cancer are time-consuming and labor-intensive. We previously found that the organization changes within the extracellular matrix fiber network can occur during cancer progression. It is desired to monitor these organization changes of extracellular matrix in a rapid way so that it can be used for cancer diagnosis. The principal component of the extracellular matrix fibers is mainly collagen. Detecting the change of collagen orientation can improve our understanding of this deadly cancer and benefit clinical diagnosis and treatments. Collagen with highly non-centrosymmetric molecular assemblies can produce SHG signal, which can be detected by multiphoton microscopy. Multiphoton microscopy is a promising non-invasive, label-free nonlinear imaging technique, which has been proven to be an important diagnostic tool for the visualization of collagen. It also possesses intrinsic advantage for 3D visualization. In this study, we use multiphoton microscopy to obtain 3D image stacks of ovarian cancer and normal tissue without the need for tedious and cumbersome tissue processing. SHG from collagen was excited using 810 nm light and the emission signal was detected in the range of 395-415nm. Then the 3D collagen orientation parameter and collagen directional variance for discriminating cancer and normal tissue was gotten by using a specific 3D image processing method. Our results show that the 3D collagen directional variances between ovarian cancer and normal tissue are distinct (p<0.05). In conclusion, the association of multiphoton microscopy with specific 3D image processing method provides a powerful tool for ovarian cancer diagnosis. It may also help physicians to improve clinical outcomes of patients with ovarian cancer.
Diagnosis for photoacoustic breast cancer images with machine learning
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Nowadays, breast cancer has increasingly threatened the health of human, especially females. However, breast cancer is still hard to detect in the early stage, and the diagnostic procedure can be time-consuming with abundant expertise needed. In this paper, the main research is the application of deep learning method in the diagnosis of photoacoustic breast cancer and the comparison of the performance of the traditional machine learning classification algorithm and deep learning method in the actual scenario of the photoacoustic imaging breast cancer diagnosis. The traditional supervised learning method firstly obtains the photoacoustic images of breast cancer through preprocessing, extracts the SIFT features, and uses K-means clustering to obtain the feature dictionary. The histogram of the feature dictionary was used as the final feature of the image. Support vector machine (SVM) was used to classify the final features, achieving an accuracy of 82.14%. In the deep learning method, AlexNet and GoogLeNet were used to perform the transfer learning, achieving 88.23%, 89.23%, and 91.18% accuracy, respectively. Finally, by comparing the AUC, sensitivity, and specificity of SVM with AlexNet and GoogLeNet, it can be concluded that the combination of deep learning and photoacoustic imaging obtain a profound and important impact on clinical applications.
Improved super-resolution optical fluctuation imaging by multiple sparse Bayesian learning method
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By exploiting the statistics of temporal fluorescent fluctuations, super-resolution optical fluctuation imaging (SOFI) can implement a fast super-resolution microscopy imaging, which is suitable for dynamic live-cell imaging. However, the main drawback of SOFI is that the imaging spatial resolution can be surpassed by the localization-based super-resolution microscopy techniques. To address this problem, we propose a new method, which is achieved by using multiple sparse Bayesian learning (M-SBL) method. Since M-SBL method can take into account simultaneously temporal fluctuations and the sparsity priors of emitter, it provides the possibility to obtain an enhancement in spatial resolution compared to standard SOFI (only considering the temporal fluctuations). To measure the performance of our proposed method, we designed three sets of simulation experiments. Firstly, we compared the performance of M-SBL and SOFI in resolving single emitter, and simulation results have demonstrated that the M-SBL method outperforms SOFI. Furthermore, the other simulation data with varying signal to noise and frame number were used to evaluate the performance of M-SBL in resolving fine structures. And the results indicate that when using the proposed M-SBL method, the imaging spatial resolution can be improved compared to the standard SOFI method. Hence, the M-SBL method provides the potential for increasing the temporal resolution of super-resolution microscopy while maintaining a desired spatial resolution.
Metronidazole-substituted dendrimer silicon phthalocyanine: a novel photodynamic therapy photosensitizer
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As an excellent second-generation photosensitizer for photodynamic therapy (PDT), phthalocyanine (Pc) complex has strong absorption peak in the near-infrared region and strong tissue penetrating ability, which endowed them excellent properties for the detection of tumor tissue. In recent years, in order to further ehnaced the penetration depth of the photosensitizer to the tissue, a large number of functional groups have been synthesized . In this work, we designed and synthesized metronidazole-substituted dendrimer silicon phthalocyanine (MT-SiPc) with near-infrared region Q-band of UV absorption, excellent fluorescence properties and photochemical properties.
Illumination and projection optics for spatial frequency domain fluorescence imaging
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A digital micromirror device (DMD) based structural illumination and projection optical system were designed and evaluated for fluorescence imaging and diffuse reflectance imaging of tissue in spatial frequency domain, respectively. Light emitting diodes (LEDs) at discrete wavelengths (532, 620, 656 nm) provided illumination for the diffuse reflectance imaging while a 532 nm laser diode (LD) was used as excitation light source of photosensitizer (PS) fluorescence. Both the LEDs and LD light were collimated, homogenized and converged on a DMD to generate the structural illumination. A projection lens was also designed to project a rectangular structural illumination spot on target tissue. The designed optical system could be applied to provide variable frequency structural illumination for depth sensitive excitation of PS and diffuse reflectance imaging.
Collagen reversible denaturation by a weak near-infrared laser light irradiation for vascular softening
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We studied collagen reversible denaturation by a weak near-infrared laser light irradiation for vascular softening. Balloon angioplasty induced about 60% restenosis rate for superficial femoral artery at 6 months after the balloon dilatation originated from mechanical injuries in vascular wall. We anticipated that mechanical injuries can be prevented by softening of the collagen fibers in vascular wall. Collagen softening is resulted from dissociation of a few hydrogen bonds in collagen molecules in general. We estimated that hydrogen bonds can be dissociated by near-infrared photon energy with less heat production because hydrogen bond energy is about 30 kJ/mol corresponding to about 4 μm in wavelength. We studied collagen denaturation by a weak near-infrared laser light irradiation from mechanical and optical characteristic changes. A collagen film derived from bovine dermis was irradiated with 980 nm wavelength semiconductor laser under the condition that temperature rise was kept under 4.1°C. To evaluate collagen denaturation from mechanical characteristic change, the elastic modulus was analyzed from the stress-strain curve of the irradiated collagen film. Stress of the collagen film was measured with a load cell when 0.25%/s strain was loaded with a rack-andpinion automatic stage. Infrared absorption spectrum peak in 3300 cm-1 band of the collagen film, which is originated from hydrogen bonds, was measured to evaluate collagen denaturation from optical characteristic change. We found that the collagen film was 12% softened by a particular laser light irradiance.
Simulation of the dose control for vascular targeted photodynamic therapy
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Dose control is one of the key factors of clinical treatment for port wine stains (PWS) under vasculature-targeted photodynamic therapy. A skin simulation model was proposed to show the PDT Type II reaction around the microcapillaries, and to establish the optimal PDT protocol such as light modulation for different PWS vascular types. A simplified two-dimensional cross section of PWS vascular composed of a single superficial epidermal layer, a deeper dermal layer, and a microcapillaries was used. A series of capillary diameters of 40, 70, 100 and 130 micrometers were used to model typical PWS lesions with different blood flow rates. Oxygen and photosensitizers (PS) are pumped from the microartery at heartbeat frequency and exit the vasculature from the microvein, and a PDT type II reaction occurs near the vessel wall: PS excited by light absorption combines with free oxygen, which leads to a reactive singlet state of oxygen (SSO) that in turn causes direct endothelial cell damage. The mathematical simulation model equations are composed of light transmission, oxygen diffusion, photosensitizer diffusion, singlet oxygen generation and photobleaching, which were solved by finite element method. With the drug diffusion and optical absorption properties of human skin, the photon consumption, drugs and oxygen diffusion and photochemical processes within the vessel wall can be simulated. This simulation can provide a quantitative method to optimize the light and drug dose for clinical treatment of PWS.
The approach for quantification assessment for port-wine stains in three-dimensional and color space
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Quantification evaluation and outcomes analysis of photodynamic therapy for port-wine stains (PWS) is usually rely on the clinician subjective assessment. The aim of this study is focused on an objective assessment model for port-wine stains during the successive treatment sessions of photodynamic therapy. The assessments of the outcome were assessed in the clearance of the lesion area before and after treatment and the trace of the lesion across the entire color space in this paper. Firstly, 3D point clouds containing the lesion coordinates and color was achieved. Then, the obtained unorganized point cloud is projected onto a specified plane to generate an organized grid, and the depth image on that plane can be also obtained. Thirdly, the lesion region is separated by using the SLIC superpixel segmentation combined with the color feature of the lesion, and the lesion was re-projected to the original three-dimensional point cloud. In the end, depending on the color and location information of the 3D lesion skin points, triangulation reconstruction was performed by the greedy projection triangulation algorithm to calculate the irregular surface area of the lesion skin. The result show that the lesion skin area based on three-dimensional space are stable and reliable regardless of the scanning angle or distance difference and the chromaticity distribution in the color space can show the recovery trend of the lesion skin at different treatment stages, so three-dimensional scanning of patients can be an approach to monitor the progress of an individual’s PWS following treatments accurately and objectively.
Detection of dental carious lesions by swept-source optical coherence tomography
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The objective of this laboratory study was to evaluate the use of a swept-source optical coherence tomography (SS-OCT) as a diagnostic tool for dental caries. The carious molars were extracted from human volunteers and examined visually using conventional dental equipment without any magnification. SS-OCT observations were carried out on the same sites as where the conventional examination had been performed. The center wavelength of SS-OCT system is 1300 nm at a 100 kHz sweep rate. The results showed that SS-OCT could clearly create cross-sectional imaging of dental structures. Moreover, carious lesions could be detected and distinguished from normal tissues. In conclusion, the SS-OCT signal could be used as a marker for early caries detection.
Effect of PSF on super-resolution ultrasound imaging implemented by bSOFI method
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Ultrasound (US) imaging technique is one of the most common imaging techniques in clinical applications. However, the spatial resolution of ultrasound is limited. Recently, a fast super-resolution ultrasound imaging (SR-US) technique has been proposed to break the diffraction limit, which is implemented by using super-resolution optical fluctuation imaging (SOFI) method. Further, to reduce the nonlinear response to brightness and blinking heterogeneities in highorder SOFI image, a balanced SOFI (bSOFI) method can also be used in SR-US. It should note that when using bSOFI method, the point spread function (PSF) of the imaging system is a key factor that affect the obtained imaging performance of SR-US. However, bSOFI is a method from optical microscopy. The PSF of optical system is significantly different from PSF of US system. To better apply bSOFI method to ultrasound, in this paper, we investigate the effect of PSF on the imaging performance of SR-US. Especially, to speed up the data acquisition and further improve the temporal resolution of SR-US, here, the US data are acquired by plane wave (PW) scan. The results from the numerical simulation indicate that when considering the characteristic of PSF in ultrasound (i.e., σ x≠ σy ), by using bSOFI method, we can greatly improve the imaging performance of US, where the smaller line structure can be effectively resolved compared to the standard US imaging method. As a result, the technique (bSOFI method combined PW scan) provide the potential in ultrafast SR-US imaging.
Assessment of tissues' inhomogeneous optical properties by a cost-effective microscope based on LED illumination
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Assessing tissues’ inhomogeneous optical properties is helpful for diagnosis, but high-cost measurement and experimental setups limit its development, data collecting and applications. In this paper, a portable microscope is proposed to assess the inhomogeneous optical properties of the sample. With a LED illumination, accurate quantitative phase (QP) map can be recovered from 5 intensity images captured at different axial positions. Then based on the scattering-phase theorem and statistical dispersion relation (SDR), the inhomogeneous optical properties of the sample can be quantitatively assessed from these QP maps. In contrast to DHM and SLIM, our setup is cost-effective, use-flexible, and with a small amount of data acquisition, thus having the potential to promote the development of assessing tissues’ inhomogeneous optical properties, especially in resource-limited areas.
Effects of substrate stiffness on the elasticity of ovarian cells using atomic force microscopy
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In this study, HOSEpiC ovarian cell was cultured on hydrogel substrates with three different Young moduli of 3, 19 and 35 kPa. Atomic force microscopy was used to measure the elasticity of cells on three different stiffness substrates. Furthermore, the distribution of actin filaments in HOSEpiC cell was observed by confocal imaging. From the measurements of atomic force microscopy, we found that substrate stiffness would cause changes of cellular elasticity. The largest one was on the substrate of 35 kPa, followed by the 19 kPa and cells on 3 kPa was the smallest. Besides, from the confocal imaging, it could be observed that the distribution of actin filaments in the cells was different on the three substrates. All these results showed that the elasticity of the cells was lower on the substrates with smaller stiffness, which indicated that cells appeared softer when the stiffness of substrate decreased.
Effect of oxidative stress stimulation on intracellular PTEN trafficking in ovarian cancer by fluorescence correlation spectroscopy
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The phosphatase and tensin homolog on chromosome 10 (PTEN) is one of important tumor suppressor proteins in ovarian cancer via negatively regulating the phosphatidylinositol 3-kinase–AKT signaling pathway and controlling genomic stability. Recent studies showed the physiological function of PTEN was closely related with its subcellular compartments. But only a few technologies could quantitatively measure the concentration of PTEN at different subcellular compartments in living cells. In this study, we used fluorescence correlation spectroscopy to measure the concentrations and dynamics of EGFP-PTEN in ovarian cancer cells HO-8910. Our results showed the increasing concentration of PTEN in the cytoplasm had an opposite trends with the nucleus after the oxidative stress stimulation which was induced by H2O2. Furthermore, the altered diffusion of PTEN at different subcellular compartments also illustrated the PTEN was trafficked from the cytoplasm to nucleus.
Optical fiber detection system for sensing singlet oxygen luminescence in aqueous solution
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Singlet oxygen (1O2) is widely recognized as the primary cytotoxic agent during photodynamic therapy (PDT). The quantitation of 1O2 generation during PDT plays an important role for 1O2 based PDT dosimetry. However, it is still a challenging task for direct detection of 1O2 using an optical system due to its extremely weak luminescence at 1270 nm. In this paper, a highly sensitive optical fiber detection system was developed to measure the time-resolved 1O2 luminescence spectra from two model photosensitizers (Rose Bengal and TMPyP) at various concentrations (1.25, 2.5, 5.0, and 10.0 μM), The 1O2 luminescence signal was excited by a diode-pumped, Q-switched, frequency-doubled 523- nm Nd:YLF laser and collected by an optical fiber probe coupled with a highly sensitive NIR photomultiplier tube (PMT). Experimental results indicate that the 1O2 luminescence intensity shows a linear enhancement both with the increase of concentrations of Rose Bengal and TMPyP. The 1O2 luminescence signal dramatically decreased after the addition of 50 mM sodium azide, a specific 1O2 quencher. Furthermore, the signal-to-noise ratio (SNR), calculated under the condition of 10 mM Rose Bengal solution, is higher than those obtained from optical fiber 1O2 luminescence detection systems based on InGaAs/InP single photon avalanche diode and superconducting nanowire single-photon detector. Our results suggest that the home-built optical fiber system with a high sensitivity for 1O2 luminescence detection will have a great potential for clinical applications in PDT dosimetry.
Spatial autocorrelation of Mueller matrix images as indicator of cervical pre-cancer detection
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An autocorrelation study has been conducted on Mueller matrix images of stromal region of cervical tissue sections for early cancer detection. Changes in multiple scattering and deterioration of stromal architecture through their spatial autocorrelation maps are observed among healthy and various grades of cervical precancerous tissues. Autocorrelation maps of diagonal elements reflects increasing depolarization property while the disease progresses. These maps of Mueller elements governing polariance, di-attenuation and birefringence properties qualitatively establish a demarcation of different grades of cancer from normal tissue. Moreover, spatial autocorrelation on optical parameters like circular di-attenuation, liner and linear-45 di-attenuation along with circular birefringence is decreasing with the evolution of cervical cancer. These preliminary results about the stromal biology are very promising in the early detection of cervical cancer.
Photoacoustic imaging with custom-designed fingertip laser diode
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Photoacoustic (PA) imaging has attracted increasing research interest in recent years due to its unique merit of combining light and sound. Enabling deep tissue imaging with high ultrasound spatial resolution and optical absorption contrast, PA imaging has been applied in various application scenarios including anatomical, functional and molecular imaging. However, the bulky and expensive laser source is one of the key bottlenecks that needs to address for further compact system development. Photoacoustic imaging system based on low-cost laser diode is one of the promising solutions. In this paper, we report a custom-made fingertip laser diode system enabling both pulsed and continuous modulation modes with the shortest pulse width of 30 ns, driving current of 10 A, and single modulation frequency of 3 MHz, which is suitable for both time and narrow-band frequency domain PA imaging. The experiments for generating PA signals were performed with more than 70 millivolts signals amplitude. By sweeping the pulse width, it is observed that the amplitude of PA signals is increasing due to higher laser energy. To the best of our knowledge, this may be the most compact laser source used for photoacoustic applications for PA imaging. Owing to its super-compact size, the reported laser diode system could pave the pathway to low-cost photoacoustic sensing and imaging device, even wearable photoacoustic biomedical sensors.
Programme to improve systems resolution in multiconfiguration sensors
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A method of continuous zoom multiple configuration, with a micro lens array and core optics is attempt to establish model by novel principle on resonance energy transfer and high accuracy localization, by which the system resolution can be improved with a level of a few nanometers. A comparative study on traditional vs modern methods can demonstrate.
Numerical simulation and experimental study on photo-thermal damage distribution of skin
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Photo-thermal response is one of the basis processes of laser irradiated tissue, dominating the laser surgical process and depending on the effect of laser treatment. To better investigate the interaction between ablative laser and skin, and more understand the light distribution and temperature distribution during the laser irradiation. Numerical simulation, which based on finite elements method (FEM), was used to solve the bio-heat and the thermal damage equations. Laser parameters can be adjustable during the process of surgery. Optical transmission, scattering coefficient and absorption coefficient in bio-tissue under laser irradiation were carried out to analyze the thermal response, which resulted from the absorbed light energy. And then, optical coherence tomography (OCT) was applied to study the injure in mice skin. The result is consistent to Numerical simulation, which will help to improve the laser therapy.
Determination optical properties of tissue-like phantoms using diffuse reflectance and transmittance spectroscopy
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We present a simple, convenient fibre-optics probe system for the determination optical properties of tissue-like liquid phantoms based on diffuse reflectance and transmittance measurements at the wavelength of visible-near-infrared region. The method combined Monte Carlo simulations, multiple polynomial regression and a Newton-Raphson algorithm for solving nonlinear equation system. In the range of optical properties of phantom with the μa at 0 – 0.5 cm-1 and the μs’ at 3 – 45 cm-1, the mean prediction error at 630 nm was 1.91 % for μs’ and 7.51 % for μa. The performance of the method is further tested by predictive error and validated using similar matrix of milk-ink phantoms on reflectance and transmittance.
Photoacoustic sensing and imaging by sharing single data acquisition channel
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As an emerging hybrid imaging modality, photoacoustic imaging has attracted intensive research interest in recent years in various applications, such as breast cancer detection, brain imaging, and intravascular imaging, which provides functional and molecular information. In a typical photoacoustic imaging system, laser intensity fluctuation needs to be monitored by a photodiode (PD) that can provide proper normalization for photoacoustic signals. Conventionally, at least two data acquisition channels are necessary to receive both photoacoustic signal and photodiode signal. In this paper, we propose a simple and efficient method to receive both photoacoustic and photodiode signals using single data acquisition channel, which gives lower system cost and faster system speed. After connecting the photodiode output and ultrasound transducer for hybrid signal acquisition, sharing channel can be achieved in two ways: Use a direct separation algorithm when received a PA signal with desirable signal-to-noise. Filters are exploited to keep low SNR PA signal immune from the photodiode signal and separate them from the receiving hybrid signal. 2D PA images based on the separated PA and PD signals will be illustrated to demonstrate their performance and efficiency. This method will be valuable especially when designing a PAT imaging system with multi-channel ultrasound array and data-acquisition card.
Characterization of the germination kinetics of individual Nosema bombycis spores using phase contrast microscopy imaging and Raman spectroscopy
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We used phase-contrast microscopy and laser tweezers Raman spectroscopy to monitor the changes of intracellular components during the spore germination of microsporidian Nosema bombycis under artificial conditions. The kinetics of image brightness of individual spores showed three-phase profile. The Raman intensities of trehalose, nucleic acid, and protein showed little changes prior to germination, but dramatically decreased once germinated, which was consistent with the kinetics of brightness of the spore. The time of spore germination (ΔTgerm) was essentially identical, but the initial time of germination (Tlag) showed obvious heterogeneity. These results demonstrate that the firing of the polar tube is not performed via trehalose transformation to the spore’s osmosis during germination. Phase-contrast microscopy imaging and Raman spectroscopy provide a more comprehensive approach to understanding the germination of microsporidian spores.
Application and development of low-level laser therapy (LLLT) for osteoporosis
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Osteoporosis (OP) is a systemic bone disease in which the bone mass reduce, the microstructure of the bone degenerate, and the bone fragility increase, which would be prone to fracture. In the light of the aging society, the incidence of osteoporosis is increasing year by year. At present, the mainstream treatment is using drugs. Although drugs have certain therapeutic effect on osteoporosis, it require long-term medication and will arise different adverse reactions. Low-level laser therapy (LLLT) is an emerging treatment in recent years. It is the application of a coherent or incoherent low-intensity laser, usually in the infrared to near-infrared 630-1000nm wavelength range, to the lesion tissue or monolayer cells to cause non-destructive and non-thermal biological reactions for therapeutic purposes. It is a physical therapy for therapeutic purposes. Studies have shown that low-level laser therapy can activate osteoblasts, promote bone repair, enhance the bone structure of peri-menopausal rat models, and increase bone density, which can be used as an effective intervention for osteoporosis in middle-aged and elderly women. This article reviews recent advances in the study of low-level laser treatment of osteoporosis.
The study of optical properties and spectral characteristics of brain glioblastoma and lung adenocarcinoma
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This paper presents qualitative analysis of terahertz time-domain spectroscopy application for cancer diagnosis by measurement of the optical properties and spectral characteristics of cancer cells. For this purpose, the cultivation of two cancer cells, U-251 (glioblastoma brain) and A549 (lung adenocarcinoma), were carried out, then their refractive index, absorption coefficient and dielectric constant were measured, and the optical properties of tumor cells were compared with the optical properties of healthy cells (fibroblasts). Tumor cells contain more OH-components in comparison with healthy cells. Since terahertz radiation is heavily absorbed by water, there are differences in the spectra of healthy and oncological cells. To obtain the optical properties and spectral characteristics of the researched objects, a terahertz time-domain spectroscopy method in the transmission mode was used. The researched cell lines were cultured in vitro. Optical properties and spectral characteristics of the samples were calculated by the thin film method and Fourier transform. The results show the differences of refractive index, absorption coefficient and dielectric permittivity between the oncological cell lines U- 251, A549 and the healthy cells in the frequency range 0.2-1 THz. It was found that cancer cells have higher values of refractive indices and absorption coefficients than those of healthy cells. Brain glioblastoma (U-251) has a transmission peak at the frequency of 0.24 THz. The results obtained in this work can form the basis for the diagnosis of brain and lung cancer with the use of terahertz time-domain spectroscopy.
Dual-contrast nonlinear photoacoustic sensing based on quasi-CW single-pulsed laser
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Photoacoustic tomography (PAT) is a non-invasive imaging technique which provided high lateral resolution and axial resolution. Conventional linear photoacoustic (PA) imaging has been widely applied to state-of-art PA system, which excited by short pulse laser. Recently, nonlinear photoacoustic effect has been excavated and utilized, which indicates the different character with linear PA by dual-pulse laser. In this paper, we report a dual-contrast photoacoustic sensing by quasi-CW nonlinear PA effect. Using the high-repetition pulsed laser, and two different contrast imaging were extracted. Unless conventional contrast that using short laser pulse by detected tissue light absorption, we extracted another contrast that indicated the rising of temperature. The quasi-CW nonlinear PA effect could be illustrated by a simple mathematical derivation. The dual-contrast PA imaging have been demonstrated by experiment in vitro and ex vivo imaging. The results indicate different heat absorbency of different materials, which could be utilized to distinguish materials and intensify imaging contrast. Compared with conventional PA imaging, the proposed method has more scope of works and potential applications.
Simulation of light absorption in tumor-embedded uterus filled with strong scattering media by diffused light sources
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Photoacoustic imaging (PAI) is a promising technique to image tumor angiogenesis development and detect endometrial carcinoma in earlier stages. The light absorption distribution of uterine tissue determines the imaging depth and range of PAI. In this work, a 3D triangular meshes tumor-embedded uterine optical model was established by the histological structure of uterus. The model is filled with strong scattering media (undiluted raw and homogenized milk, URHM) and air, respectively. Monte Carlo simulation is implemented based on the molecular optical simulation environment (MOSE) to find the absorption profiles of photons by transcervical laser illumination with cylindrically diffused light source (CDLS) or spherically diffused light source (SDLS) at wavelength 800nm. The results show the media with an extremely high scattering coefficient and an extremely low absorption coefficient like URHM helps the light propagations in a relatively small cavity. CDLS performs better when the tumor happens far from the light source center than the SDLS. On the same time, embedded tumors of the model filled with URHM are easier to detect by the transcervical laser illumination of CDLS than SDLS in the fundus of the uterus. The conclusions are helpful to optimize the laser source and to improve the imaging depth in a photoacoustic imaging system.
Photoacoustic imaging of gastric cancer in vitro based on water-soluble nanoscale gold rods
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With the development of diagnostic and therapeutic options in gastric cancer, the incidence of gastric cancer is decreasing over the past two decades. However, it is still necessary to improve the early diagnosis technology of gastric cancer to reduce the mortality of gastric cancer. Photoacoustic imaging is a rapidly developing diagnostic modality of cancer which is based on optical excitation and ultrasonic detection. In this paper, photoacoustic imaging is proposed as a visual tool to compound structural and location information for early stage gastric cancer detection by using nanoscale gold rods. The experimental results showed that the nanoscale gold rods can increase penetration depth of tumor in addition to that diagnosing the early gastric cancer with no obvious symptoms.
Cuff-less blood pressure measurement using fingertip photoplethysmogram signals and physiological characteristics
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Blood pressure (BP) measurement data is an important indication of health and quality of life in clinical medicine and daily life. However, conventional measurement does not provide continuous monitoring data and sometimes is considered as inconvenient. With the ever increased urge for cuff-less continuous BP measurement, novel methods based on pulse transit time (PTT) obtained from the photoplethysmogram (PPG) and electrocardiogram (ECG) signals have gained its popularity. However, the collection of ECG signals involves the application of electrodes and inconvenience due to lengthy continuous measurement. In contrast, the collection of PPG signals is comparatively simpler and easier, therefore, novel methods that extract features from PPG signal are receiving more attentions. However, previous studies only focus on the features extracted from the PPG signal and did not include the physiological characteristics, which can serve as important predictors for BP. To improve the accuracy in the estimation of BP based on the PPG signal, this study not only extracts features from the PPG signal, but also includes the physiological characteristics of total 191 sets of subjects, such as height, weight, and age. After pre-processing the raw PPG signal, different machine learning methods are used to estimate the diastolic blood pressure (DBP) and the systolic blood pressure (SBP). The mean absolute error of DBP and SBP are 4.13 mmHg and 9.18 mmHg respectively. The results complied with the British Hypertension Society (BHS) standards and the implementation of physiological characteristics improved the accuracy of BP estimation.
In vivo imaging prednisolone-induced osteoporosis of the adult zebrafish with spectral domain optical coherence tomography
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Osteoporosis studies require precise visualization of the morphological structures. The adult zebrafish represents an excellent model to investigate osteoporosis. However, few imaging methods can effectively detect the adult zebrafish bone structure in real time with high resolution and good penetration depth. In this paper, long-term in vivo monitoring of Prednisolone-induced osteoporosis is achieved with spectral-domain optical coherence tomography (SD-OCT). The SD-OCT is able to noninvasively visualize the skull injury and osteoporosis of adult zebrafish. Valuable phenomenon such as the skull defect and bone loss can be conducted based on the SD-OCT images at different time points during a period of 21 days.
Wrist pulse signal acquisition by video motion processing
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Traditional sensors and systems for wrist pulse acquisition, known as inconvenient, contact, depends on the digital and analog circuits. In this paper, a method in video motion processing at one-demensional signal extraction and analysis is proposed. It can be applied for wrist pulse acquisition and based on subtle video motion amplification algorithm. This is the demostraction of a low-cost (only need ordinary camera on the cell phone), accurate method for cantact-free wrist pulse acquiring that is capable of performing measurements in different illumination conditions. As the ultimate recovered single and all periodic pulse signal shown, it can be demonstracted that the proposed method can get accurate pulse signal compared to traditional methods.
FEM simulation of laser-generated ultrasonic waves in human skin in different epidermal thickness
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The Laser-Ultrasonic technique uses laser energy to generate ultrasound waves in various solids. In normal conditions, this technique is used to inspect large structures without destruction, but in military use, we hope get this destruction. Different races and different parts of the human body have different thickness of the epidermis. When the laser irradiates the human skin, different thickness of the skin will inevitably affect the results. In this paper, 10 laser pulses were simulated to irradiate human skin with different thickness of epidermis. The results show that the thinner the thickness of epidermis, the greater the temperature rise of skin, and the greater the displacement. When the thickness is more than 200 microns, the temperature change under the skin is not obvious, but the displacement direction changes and the displacement amplitude is smaller than the positive displacement.
Detection of tilted fiber Bragg grating fiber-optic sensors with short-term KLT: towards low-cost biosensors
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Tilted Fiber Bragg Grating (TFBG) optical fiber sensors can be employed as refractive index sensors, and functionalized as biosensors. The TFBG cladding modes exhibit a small yet detectable sensitivity to the refractive index in the surrounding of the sensing region. One of the weaknesses of TFBG is that classical interrogation methods require narrow wavelength resolution to analyze these spectral features which can be achieved only through a bulky setup. In this work, we propose a demodulation method, namely the short term Karhunen-Loeve Transform (ST-KLT) that can be applied to a low-cost spectrometer that detects the TFBG reflection spectrum. The method is capable of detecting refractive index variations in the order of 10-3 - 10-4 refractive index units (RIU), and is a potential pillar towards low-cost TFBG biosensors.
An etched chirped fiber Bragg grating for measurement of refractive index and temperature pattern
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In this work, partially etched chirped fiber Bragg grating (pECFBG) for the real-time multi-parameter measurement of temperature and refractive index is proposed. The sensor is fabricated by wet-etching a portion of a linearly chirped FBG with linear chirp profile. Obtained CFBG has two active areas: the unetched part of the grating that can be used either as a uniform temperature sensor, or to detect thermal gradients experienced through the grating length; the etched part, besides having a similar thermal sensitivity, is exposed to refractive index sensing through the variations of external refractive index. Overall, the pECFBG structure behaves as a compact sensor with multi-parameter capability, that can both measure temperature and refractive index on the same grating, but also spatially resolve temperature detection through the grating section. The results have been validated through both a model and experimental setup, showing that the mutual correlation algorithm applied to different spectral parts of the grating is able to discriminate between uniform and gradient-shaped temperature profiles, and refractive index changes. The reflected spectra showed a clear correlation between the RI change of the surrounding media and spectral shift with temperature variations.
Evaluation of singlet oxygen luminescence of a novel chlorin photosensitizer
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Photodynamic therapy (PDT) utilizes the combined action of photosensitizer, light and molecular oxygen to generate singlet oxygen to treat various diseases. Photosensitizer is a key component and its optical properties and singlet oxygen quantum yield determine the effectiveness of its photodynamic reaction. This study evaluated the singlet oxygen production of a novel water solubility chlorin photosensitizer - namely YLG-I, which was developed in China. The absorption spectra and singlet oxygen luminescence different solvents were evaluated. It was estimated that the singlet oxygen quantum yield of the new photosensitizer YLG-I was at the same level of the potent chlorin sensitizer mTHPC. Preliminary evaluation suggested that YLG-I was a promising photosensitizer for PDT. This presentation will report the detection of singlet oxygen luminescence of the newly developed PDT sensitizer.
Label-free imaging using multimodal microscopy in vivo and in vitro
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Many imaging technologies, such as two photon microscopy (TPM), second generation microscopy (SHG) and photoacoustic microscopy (PAM), have successfully demonstrated the ability to extract anatomical, functional and molecular information of biological samples. However, they always fail to obtain comprehensive information from biological tissue due to single imaging modality. To address this limitation, we developed a multimodal microscopy with fully integrated PAM, TPM and SHG. The home-built multimodal microscopy system enable label-free imaging of biomedical tissue with sub-micron resolution in vivo and in vitro. The results may offer a new tool to provide the capable of fast comprehensive information capturing for biological studies.
In vivo monitoring optical clearing process of skin using two-photon microscopy
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The skin is the largest organ in the human body, and it is an important window for optical imaging and diagnosis. However, the turbid characteristics of skin limits the penetration of light. Skin optical clearing technique provides an important tool for improving optical imaging performance. However, study on mechanism for skin optical clearing was mostly based on ex vivo skin experiments, the in vivo skin optical clearing process still needs further exploration. In this work, we can in vivo monitor the changes in skin during treatment of skin optical clearing agent by using two-photon imaging. For untreated skin, collagen has a strong second harmonic generation (SHG) signal, the structure of epidermis and collagen is relatively complete. After treatment of skin optical clearing agent, the SHG signal of collagen is significantly weakened. After optical clearing agent removed and saline treated, the skin can recover to initial state obviously, and the SHG is greatly enhanced, even is stronger than initial level. The results indicated that the treatment of optical clearing agents (OCA) can induce the structural change of skin, which lead to skin transparent consequently, and optical clearing agent–induced decrease of collagen SHG is invertible by recovery with treatment of physiological saline. This work is very helpful for understanding the in vivo skin optical clearing process, which is of great significant to revealing the mechanism of in vivo skin optical clearing.
Method of detection of resting heart rate based on imaging photoplethysmography technology
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Resting heart rate (RHR) is considered an important biomedical indicator to evaluate cardiovascular function. High RHR is an important prognostic factor for sudden cardiac death and heart failure in the general population, and especially among patients with known cardiac disease. The imaging photoplethysmography (IPPG) technology is used to achieve the accurate detection of RHR signal, which has the advantages of low cost, simple operation, fast acquisition speed etc. In this paper, we propose a new simple, inexpensive and easy-to-use method to measure the RHR in vivo. The result shows that Fast Fourier Transform with Hamming window filters, band-pass filter gives more accurate results. The color change of the fingertip is enlarged by using the mobile phone camera. From the distribution of color change of the fingertip, the RHR is estimated with the primary calibration result of the relationship between color variation and the blood volume change.
The impact of optical radiation of femtosecond duration on human glial cells
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The paper presents the results of the studies of influence of optical radiation with wavelengths of 520 and 780 nm on human glial cells (U251) at the range of exposure times ~ 1-15 min. It was found that after the first minute of irradiation at the wavelength of 780 nm, the relative number of apoptotic cells significantly increased. The result corroborates the concept of biological hazard of optical radiation for tumor cells, and suggests that the approach has a great potential in clinical application for the treatment of human glioma.
Impacts of vascular diameter and depth on singlet oxygen luminescence imaging in tissue simulating phantom
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Singlet oxygen (1O2) is the primary cytotoxic production in type-II photodynamic therapy (PDT). The correlation between 1O2 generation and PDT efficacy during treatment has received considerable attention. The direct detection of 1O2 luminescence is the gold standard for 1O2 identification. However, the intensity of 1O2 luminescence could be influenced by tissue optical properties, location and morphology of lesion, especially for vascular targeting PDT. In this study, the impacts of vascular diameter and depth on 1O2 luminescence imaging have been investigated in tissue simulating phantom. A near-IR sensitive InGaAs camera with adaptive optics and CW laser 532 nm were used for fast imaging of 1O2 luminescence. Rose Bengal (RB) was used as photosensitizer to generate 1O2 during photosensitization. Intralipid was diluted with different concentrations in order to establish the scattering properties of tissues. The capillary tubes, containing solution of RB, with varied diameters from 0.1 to 0.9 mm were used to simulate the vascular with the depth varied from 0 to 5 mm in phantom. The preliminary results indicate that the profile range ratio of 1O2 luminescence images are negatively correlated to the diameter of capillary tube, and the attenuation of intensity of 1O2 luminescence is non-linear with the increase of depth.
Esophageal cancer detection based on two-photon excitation fluorescence combined with membrane electrophoresis of blood serum
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Nonlinear optical spectroscopy has wide applications in the medical field with special advantages. Through combining nonlinear optical spectroscopy with membrane electrophoresis, we endeavored to develop a novel method for blood serum analysis for cancer detection applications. In this method, albumin and globin are isolated from blood serum by membrane electrophoresis to perform two-photon excitation fluorescences (TPEF) spectral analysis. The obtained spectra present rich signatures of the biochemical constituents of whole proteins. We evaluated the utility of this method by analyzing albumin and globin samples of blood serum from esophageal cancer patients and healthy volunteers. Twophoton excitation fluorescences revealed that esophageal cancer group can be unambiguously discriminated from the normal group, and I457/I639, I511/I639, and I543/I639 ratios can be used as indicators to diagnose early esophageal cancer. These results are very promising for developing a label-free, non-invasive clinical tool for early cancer detection and screening.
The effects of water-mediated cavitation on hard tissue ablation with Ho:YAG laser
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Liquid-assisted hard tissue ablation has been paid more and more attentions in recent years and its enhancement mechanism has not yet been fully understood. In the present paper, the dynamic process of cavitation bubble and microjet generation induced by Ho:YAG laser, as well as their effects on hard dental tissue ablation were monitored by a high-speed camera. The results showed that the maximum size of the cavitation bubble increases with the increase of laser energy, and the collapse time of cavitation bubbles is also extended accordingly.
Detection of limb ischemia based on Eulerian Video Magnification
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The study of micro-motion amplification technology has been widely concerned. Eulerian Video Magnification is one of the methods of concern and affirmation. Ischemia refers to the lack of blood flowing in certain parts of the body, which can occur in the limb, heart, brain or other parts of the body. Ischemia is a serious disease, which can cause serious tissue damage or let limbs not move. In this paper, we use Eulerian Video Magnification to initially detect whether someone suffers from limb ischemia by amplifying the movement of limb blood.
Pigmented skin lesion segmentation based on random forest and full convolutional neural networks
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Segmentation of pigmented lesions is often affected by factors such as hair around the skin lesions, artificial markings, etc., and the complexity of the lesion itself, such as lesions and skin boundaries is not clear, the internal color of lesions is variable, etc., resulting in segmentation difficulties. Aiming at the problem that the segmentation method of pigmented skin lesions using only random forests is not accurate, a segmentation method for pigmented skin lesion using a combination of random forest and fully convolutional neural networks (FCN) is proposed. This method firstly classifies and recognizes skin lesion images based on random forests to obtain a probability distribution of the lesions and the background. Then, the other probability distribution is obtained using FCN based on an improved loss function. Finally, the classification results of random forest and FCN are fused into the final image segmentation results. The experimental results show that the combination of random forest and FCN yields better performances than using random forest alone, in particular, can increase the sensitivity by about 20%.
Finite element simulation of pulsed laser-induced thermotherapy for biological liver tissue
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Laser-induced thermotherapy (LITT) predicts the effects of laser applications in LITT and optimizes the efficacy of irradiation plans, the light distribution in liver tissue, the optical tissue properties, and the changes caused by thermal denaturation. In this paper, COMSOL Multiphysics, a commercially available Finite Element (FE) simulation software package, was used to simulate the interaction between laser and liver tissue. A short-pulse laser point source, coagulated liver tissue and uniform soft tissue submerged in water were established. In this study, two sets of simulation models were used to describe the principles: 1) Diffusion equation was used to simulate light propagation; 2) Temperature changes were simulated using biothermal equations. The experimental results show that there are significant differences in penetration depth and light energy distribution of native and coagulated liver tissues under laser irradiation with different wavelengths. The penetration depth of the liver tissue after heat coagulation is significantly reduced. In addition, the simulation can present the temperature curve during the clinical hyperthermia of liver cancer and determine the effect by various treatment parameters. These results provide a better understanding of laser-tissue interactions and may be helpful to researchers in the fields of laser medical.
Distributed strain sensing medical catheter for epidural anesthesia
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Epidural anesthesia is a pain relief method achieved by injecting anesthetic into the epidural space using a medical catheter inserted in an epidural needle. To reach the epidural space, the needle penetrates through subcutaneous fat, interspinous ligament, intraspinous ligament and ligamentum flavum. Existing manual methods for epidural space identification are based on the decrease of pressure applied to the needle when it penetrates from the dense ligamentum flavum to the soft epidural space. The failure rate of the manual techniques is high. This work proposes to measure the strain using a single-mode optical fiber, mounted externally on the needle. By the use of an optical backscattering reflectometer, it is possible to achieve a distributed strain sensing over the whole length of the needle. The spectral intensity distribution of the scattered light changes when the optical fiber is exposed to strain variations, so a strain pattern can be retrieved by correlating the unperturbed spectrum to the perturbed one. According to the strain pattern, obtained during the needle insertion into a custom made phantom, which mimics the spinal anatomy, when the needle penetrates the ligamentum flavum, a significant strain increase is determined. When the needle pierces the soft epidural space, the strain slightly drops. The proposed design brings the following advantages: optical fiber embedded externally on the needle does not obstruct the flow of anesthetic fluid; the whole needle acts as a sensor which allows the operator to discriminate tissue layers as well as to define the epidural space.
Efficacy of deep convolutional neural network features on histological manifold for robust breast carcinoma detection
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In this study, exploratory deep feature engineering using convolutional neural network (CNN) on histological manifold has been proposed for robust breast carcinoma detection. A comparative evaluation emphasizing the adequacy of manifold learning and CNN aided deep features over state-of-the-art biomarkers and other deep learning models is done for histopathological image (HI) classification. The proposed framework efficiently differentiate the spatial textural non-stationarity in HI and apprehend the topographic aberrations of cancerous tissues and exemplifies its competency for clinical settings deployment in developing countries. Experimental results are discussed in detail.