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18 pages, 25881 KiB

Open AccessArticle

Optimization of the Distance between Cylindrical Light Distributors Used for Interstitial Light Delivery in Biological Tissues

by Aurélien Gregor, Shohei Sase and Georges Wagnieres

Photonics 2022, 9(9), 597; https://doi.org/10.3390/photonics9090597 - 23 Aug 2022

Cited by 2 | Viewed by 2403

Abstract

Cylindrical light diffusers (CLDs) are often employed for the treatment of large tumors by interstitial photodynamic therapy (iPDT) and photoimmunotherapy (PIT), which involves careful treatment planning to maximize therapeutic dose coverage while minimizing the number of CLDs used. There is, however, a lack [...] Read more.

Cylindrical light diffusers (CLDs) are often employed for the treatment of large tumors by interstitial photodynamic therapy (iPDT) and photoimmunotherapy (PIT), which involves careful treatment planning to maximize therapeutic dose coverage while minimizing the number of CLDs used. There is, however, a lack of general guidelines regarding optimal positioning of CLDs, in particular when they are inserted in parallel to treat head and neck squamous cell cancer (HNSCC). Therefore, the purpose of this study is to determine the CLD-CLD distances maximizing the necrosis for different geometries of CLD positions and shed light on the influence of different optical parameters on this distance, in particular when HNSCCs are treated by interstitial PIT with cetuximab–IR700 using up to seven CLDs. To that end, Monte-Carlo simulations of the light propagation around CLDs inserted perpendicularly in a semi-infinite tumor were performed to determine the volume receiving a fluence larger than a therapeutic threshold. An optimization algorithm was then used to calculate and maximize the necrosed tumor volumes. Tumor optical properties were derived from published data. Our findings suggest that optimal CLD positioning maximizing the volume of necrosed tumor during interstitial PIT for typical HNSCC optical properties corresponds to a CLD-CLD distance between 11.5- and 13-mm. Variations of the absorption and reduced scattering coefficients have the greatest influence on CLD placements, while tissue anisotropy factor, CLD insertion geometry, CLD length, and the angular dependence of the radiance emitted by the CLDs have minimal influence. At first approximation the influence of these optical parameters on optimal CLD-CLD distance are independent. Our data also suggests it is possible to derive new treatment plans using knowledge of previous treatment plans. Full article

(This article belongs to the Special Issue Tissue Optics)

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13 pages, 4050 KiB

Open AccessArticle

Probing Dynamic Variation of Layered Microstructure Using Backscattering Polarization Imaging

by Tongjun Bu, Conghui Shao, Yuanhuan Zhu, Tongyu Huang, Qianhao Zhao, Yanan Sun, Yi Wang and Hui Ma

Photonics 2022, 9(3), 153; https://doi.org/10.3390/photonics9030153 - 4 Mar 2022

Cited by 3 | Viewed by 2057

Abstract

Polarization imaging can quantitatively probe the microscopic structure of biological tissues which can be complex and consist of layered structures. In this paper, we established a fast-backscattering Mueller matrix imaging system to characterize the dynamic variation in the microstructure of single-layer and double-layer [...] Read more.

Polarization imaging can quantitatively probe the microscopic structure of biological tissues which can be complex and consist of layered structures. In this paper, we established a fast-backscattering Mueller matrix imaging system to characterize the dynamic variation in the microstructure of single-layer and double-layer tissues as glycerin solution penetrated into the samples. The characteristic response of Mueller matrix elements, as well as polarization parameters with clearer physics meanings, show that polarization imaging can capture the dynamic variation in the layered microstructure. The experimental results are confirmed by Monte Carlo simulations. Further examination on the accuracy of Mueller matrix measurements also shows that much faster speed has to be considered when backscattering Mueller matrix imaging is applied to living samples. Full article

(This article belongs to the Special Issue Tissue Optics)

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14 pages, 2880 KiB

Open AccessArticle

Fast Estimation of the Spectral Optical Properties of Rabbit Pancreas and Pigment Content Analysis

by Inês Soraia Martins, Hugo Filipe Silva, Valery Victorovich Tuchin and Luís Manuel Oliveira

Photonics 2022, 9(2), 122; https://doi.org/10.3390/photonics9020122 - 21 Feb 2022

Cited by 7 | Viewed by 2030

Abstract

The pancreas is a highly important organ, since it produces insulin and prevents the occurrence of diabetes. Although rare, pancreatic cancer is highly lethal, with a small life expectancy after being diagnosed. The pancreas is one of the organs less studied in the [...] Read more.

The pancreas is a highly important organ, since it produces insulin and prevents the occurrence of diabetes. Although rare, pancreatic cancer is highly lethal, with a small life expectancy after being diagnosed. The pancreas is one of the organs less studied in the field of biophotonics. With the objective of acquiring information that can be used in the development of future applications to diagnose and treat pancreas diseases, the spectral optical properties of the rabbit pancreas were evaluated in a broad-spectral range, between 200 and 1000 nm. The method used to obtain such optical properties is simple, based almost on direct calculations from spectral measurements. The optical properties obtained show similar wavelength dependencies to the ones obtained for other tissues, but a further analysis on the spectral absorption coefficient showed that the pancreas tissues contain pigments, namely melanin, and lipofuscin. Using a simple calculation, it was possible to retrieve similar contents of these pigments from the absorption spectrum of the pancreas, which indicates that they accumulate in the same proportion as a result of the aging process. Such pigment accumulation was camouflaging the real contents of DNA, hemoglobin, and water, which were precisely evaluated after subtracting the pigment absorption. Full article

(This article belongs to the Special Issue Tissue Optics)

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11 pages, 3240 KiB

Open AccessCommunication

Quantitative Photoacoustic Reconstruction of the Optical Properties of Intervertebral Discs Using a Gradient Descent Scheme

by Antoine Capart, Julien Wojak, Roman Allais, Moncef Ghiss, Olivier Boiron and Anabela Da Silva

Photonics 2022, 9(2), 116; https://doi.org/10.3390/photonics9020116 - 18 Feb 2022

Cited by 3 | Viewed by 1644

Abstract

The intervertebral discs (IVD) are among the essential organs of the human body, ensuring the mobility of the spine. These organs possess a high proportion of water. However, as the discs age, this content decreases, which can potentially lead to various diseases called [...] Read more.

The intervertebral discs (IVD) are among the essential organs of the human body, ensuring the mobility of the spine. These organs possess a high proportion of water. However, as the discs age, this content decreases, which can potentially lead to various diseases called degenerative disc diseases. This water content is therefore an important indicator of the well-being of the disc. In this paper, we propose photoacoustic imaging as a means of probing a disc and quantitatively recovering its molecular composition, which should allow concluding on its state. An adjoint-assisted gradient descent scheme is implemented to recover the optical absorption coefficient in the disc, from which, if spectroscopic measurements are performed, the molecular composition can be deduced. The algorithm was tested on synthetic measurements. A realistic numerical phantom was built from magnetic resonance imaging of an actual IVD of a pig. A simplified experiment, with a single laser source, was performed. Results show the feasibility of using photoacoustics imaging to probe IVDs. The influences of exact and approximate formulations of the gradient are studied. The impact of noise on the reconstructions is also evaluated. Full article

(This article belongs to the Special Issue Tissue Optics)

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15 pages, 4911 KiB

Open AccessArticle

Evaluation of Mannitol Intervention Effects on Ischemic Cerebral Edema in Mice Using Swept Source Optical Coherence Tomography

by Zhenhe Ma, Ziyue Meng, Yifu Tian, Jian Liu, Ang Li, Yang Lin, Yao Yu, Jingmin Luan, Hongtu Wang, Yuqian Zhao and Yi Wang

Photonics 2022, 9(2), 81; https://doi.org/10.3390/photonics9020081 - 30 Jan 2022

Cited by 4 | Viewed by 3853

Abstract

Cerebral edema is a serious complication of ischemic cerebrovascular disease and mannitol is a commonly used dehydrating agent for relieving cerebral edema. However, the edema state and surrounding vascular perfusion level during mannitol treatment remains unclear, which affects the clinical application of the [...] Read more.

Cerebral edema is a serious complication of ischemic cerebrovascular disease and mannitol is a commonly used dehydrating agent for relieving cerebral edema. However, the edema state and surrounding vascular perfusion level during mannitol treatment remains unclear, which affects the clinical application of the medicine. In this paper, we demonstrated the role of swept-source optical coherence tomography (OCT) in the evaluation of mannitol efficacy using mouse models. The OCT-based angiography and attenuation imaging technology were used to obtain the cerebral vascular perfusion level and cerebral edema state at different times. Vascular parameters and edema parameters were quantified and compared. Experimental results show that mannitol can significantly reduce the water content in the central region of edema, effectively inhibiting the rapid growth of the edema area, and restoring cerebral blood flow. On average, the edema area decreased by 33% after 2 h, and the vascular perfusion density increased by 12% after 5 h. This work helps to provide a valuable theoretical basis and research ideas for the clinical treatment of cerebral edema. Full article

(This article belongs to the Special Issue Tissue Optics)

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9 pages, 1649 KiB

Open AccessCommunication

Comparison of the Capabilities of Spectroscopic and Quantitative Video Analysis of Fluorescence for the Diagnosis and Photodynamic Therapy Control of Cholangiocellular Cancer

by Dmitry Yakovlev, Artem Shiryaev, Dina Farrakhova, Tatiana Savelieva, Kanamat Efendiev, Maxim Loshchenov, Gleb Zhemerikin, Marine Amouroux, Christian Daul, Walter Blondel, Igor Reshetov and Victor Loschenov

Photonics 2022, 9(2), 65; https://doi.org/10.3390/photonics9020065 - 26 Jan 2022

Cited by 1 | Viewed by 2416

Abstract

Cholangiocellular cancer (CCC) is a malignant neoplasm of the hepatobiliary system that is difficult to diagnose and treat. Currently, the most effective treatment of CCC is demonstrated under the control by fluorescent diagnosis. Photodynamic therapy (PDT) has also shown good results in the [...] Read more.

Cholangiocellular cancer (CCC) is a malignant neoplasm of the hepatobiliary system that is difficult to diagnose and treat. Currently, the most effective treatment of CCC is demonstrated under the control by fluorescent diagnosis. Photodynamic therapy (PDT) has also shown good results in the treatment of this disease, and fluorescence analysis of the photosensitizer is a good approach to control PDT. This article presents the results of a comparison of spectroscopic and quantitative video-fluorescent analysis of chlorin e6 photosensitizer fluorescence in vivo during cholangiocellular cancer surgery. Spectroscopic analysis provides accurate information about the concentration of the photosensitizer in the tumor, while the video-fluorescence method is convenient for visualizing tumor margins. A direct correlation is shown between these two methods when comparing the fluorescence signals before and after PDT. The applied paired Student’s t-test shows a significant difference between fluorescence signal before and after PDT in both diagnostic methods. In this regard, video-fluorescence navigation is not inferior in accuracy, sensitivity, or efficiency to spectroscopic methods. Full article

(This article belongs to the Special Issue Tissue Optics)

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9 pages, 3453 KiB

Open AccessArticle

Design and Simulation of an Ultra-Wide Field Optical Coherence Tomography Retinal Imaging System

by Shanshan Liang, Xinyu Li, Jiajing Kang, Mingming Wan, Jiahui Wang and Jun Zhang

Photonics 2021, 8(11), 476; https://doi.org/10.3390/photonics8110476 - 27 Oct 2021

Cited by 1 | Viewed by 2544

Abstract

Peripheral retinal imaging is a unique approach for assessing and monitoring ocular diseases. In this paper, we proposed a design for an optical coherence tomography system to accomplish ultrawide field (>120°) retinal imaging without montages. Scanning of the sample arm was achieved via [...] Read more.

Peripheral retinal imaging is a unique approach for assessing and monitoring ocular diseases. In this paper, we proposed a design for an optical coherence tomography system to accomplish ultrawide field (>120°) retinal imaging without montages. Scanning of the sample arm was achieved via two ellipsoidal mirrors. The optical design software Zemax and an eye model were used to estimate the inherent aberrations in the system and the optical performance of retinal imaging. Simulation results of the aberrations in the designed system indicated that the designed system can achieve an unprecedented imaging field of view (FOV) while maintaining acceptable resolution without sacrificing the working distance. This work suggests that ultrawide field optical coherence tomography retinal imaging is achievable, which is highly important for the diagnosis and treatment of ocular—especially peripheral—retinopathy. Full article

(This article belongs to the Special Issue Tissue Optics)

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23 pages, 1079 KiB

Open AccessArticle

Proposal for a Skin Layer-Wise Decomposition Model of Spatially-Resolved Diffuse Reflectance Spectra Based on Maximum Depth Photon Distributions: A Numerical Study

by Victor Colas, Walter Blondel, Grégoire Khairallah, Christian Daul and Marine Amouroux

Photonics 2021, 8(10), 444; https://doi.org/10.3390/photonics8100444 - 14 Oct 2021

Cited by 10 | Viewed by 3210

Abstract

In the context of cutaneous carcinoma diagnosis based on in vivo optical biopsy, Diffuse Reflectance (DR) spectra, acquired using a Spatially Resolved (SR) sensor configuration, can be analyzed to distinguish healthy from pathological tissues. The present contribution aims at studying the depth distribution [...] Read more.

In the context of cutaneous carcinoma diagnosis based on in vivo optical biopsy, Diffuse Reflectance (DR) spectra, acquired using a Spatially Resolved (SR) sensor configuration, can be analyzed to distinguish healthy from pathological tissues. The present contribution aims at studying the depth distribution of SR-DR-detected photons in skin from the perspective of analyzing how these photons contribute to acquired spectra carrying local physiological and morphological information. Simulations based on modified Cuda Monte Carlo Modeling of Light transport were performed on a five-layer human skin optical model with epidermal thickness, phototype and dermal blood content as variable parameters using (i) wavelength-resolved scattering and absorption properties and (ii) the geometrical configuration of a multi-optical fiber probe implemented on an SR-DR spectroscopic device currently used in clinics. Through histograms of the maximum probed depth and their exploitation, we provide numerical evidence linking the characteristic penetration depth of the detected photons to their wavelengths and four source–sensor distances, which made it possible to propose a decomposition of the DR signals related to skin layer contributions. Full article

(This article belongs to the Special Issue Tissue Optics)

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11 pages, 1657 KiB

Open AccessArticle

Intraoperative Control of Hemoglobin Oxygen Saturation in the Intestinal Wall during Anastomosis Surgery

by Daniil M. Kustov, Tatiana A. Savelieva, Timofey A. Mironov, Sergey S. Kharnas, Vladimir V. Levkin, Andrey S. Gorbunov, Artem A. Shiryaev and Victor B. Loschenov

Photonics 2021, 8(10), 427; https://doi.org/10.3390/photonics8100427 - 4 Oct 2021

Cited by 4 | Viewed by 2152

Abstract

During surgery for colon cancer, monitoring of the oxygen saturation of hemoglobin in the tissues under study makes it possible to assess the degree of blood supply to the anastomosis areas of the colon. Adequate blood supply in this area is decisive in [...] Read more.

During surgery for colon cancer, monitoring of the oxygen saturation of hemoglobin in the tissues under study makes it possible to assess the degree of blood supply to the anastomosis areas of the colon. Adequate blood supply in this area is decisive in terms of the consistency of the anastomosis and can significantly reduce the risk leakage of anastomosis. In this work, we propose a new approach to assessing the hemoglobin oxygen saturation based on measuring both the diffuse reflectance and transmittance spectra of the colon wall tissues. The proposed method is based on the use of two fiber-optic tools for irradiation from both sides—the intestinal lumen and the outside of the intestinal wall. The spectra are recorded from the external side. To determine the degree of hemoglobin saturation, two algorithms, both based on the Taylor series expansion of the coefficient of light attenuation by tissues, are proposed. The results of a clinical study of the proposed approach on volunteers were obtained, allowing to draw a conclusion about the applicability of the approach in a clinical setting. Full article

(This article belongs to the Special Issue Tissue Optics)

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13 pages, 5672 KiB

Open AccessArticle

Multimodal and Multiview Wound Monitoring with Mobile Devices

by Evelyn Gutierrez, Benjamín Castañeda, Sylvie Treuillet and Ivan Hernandez

Photonics 2021, 8(10), 424; https://doi.org/10.3390/photonics8100424 - 2 Oct 2021

Cited by 4 | Viewed by 2545

Abstract

Along with geometric and color indicators, thermography is another valuable source of information for wound monitoring. The interaction of geometry with thermography can provide predictive indicators of wound evolution; however, existing processes are focused on the use of high-cost devices with a static [...] Read more.

Along with geometric and color indicators, thermography is another valuable source of information for wound monitoring. The interaction of geometry with thermography can provide predictive indicators of wound evolution; however, existing processes are focused on the use of high-cost devices with a static configuration, which restricts the scanning of large surfaces. In this study, we propose the use of commercial devices, such as mobile devices and portable thermography, to integrate information from different wavelengths onto the surface of a 3D model. A handheld acquisition is proposed in which color images are used to create a 3D model by using Structure from Motion (SfM), and thermography is incorporated into the 3D surface through a pose estimation refinement based on optimizing the temperature correlation between multiple views. Thermal and color 3D models were successfully created for six patients with multiple views from a low-cost commercial device. The results show the successful application of the proposed methodology where thermal mapping on 3D models is not limited in the scanning area and can provide consistent information between multiple thermal camera views. Further work will focus on studying the quantitative metrics obtained by the multi-view 3D models created with the proposed methodology. Full article

(This article belongs to the Special Issue Tissue Optics)

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12 pages, 1173 KiB

Open AccessArticle

Characterization of Collagen I Fiber Thickness, Density, and Orientation in the Human Skin In Vivo Using Second-Harmonic Generation Imaging

by Marius Kröger, Johannes Schleusener, Sora Jung and Maxim E. Darvin

Photonics 2021, 8(9), 404; https://doi.org/10.3390/photonics8090404 - 21 Sep 2021

Cited by 12 | Viewed by 4350

Abstract

The assessment of dermal alterations is necessary to monitor skin aging, cancer, and other skin diseases and alterations. The gold standard of morphologic diagnostics is still histopathology. Here, we proposed parameters to distinguish morphologically different collagen I structures in the extracellular matrix and [...] Read more.

The assessment of dermal alterations is necessary to monitor skin aging, cancer, and other skin diseases and alterations. The gold standard of morphologic diagnostics is still histopathology. Here, we proposed parameters to distinguish morphologically different collagen I structures in the extracellular matrix and to characterize varying collagen I structures in the skin with similar SAAID (SHG-to-AF Aging Index of Dermis, SHG—second-harmonic generation; AF—autofluorescence) values. Test datasets for the papillary and reticular extracellular matrix from images in 24 female subjects, 36 to 50 years of age, were generated. Parameters for SAAID, edge detection, and fast Fourier transformation directionality were determined. Additionally, textural analyses based on the grey level co-occurrence matrix (GLCM) were conducted. At first, changes in the GLCM parameters were determined in the native greyscale images and, furthermore, in the Hilbert-transformed images. Our results demonstrate a robust set of parameters for noninvasive in vivo classification for morphologically different collagen I structures in the skin, with similar and different SAAID values. We anticipate our method to enable an automated prevention and monitoring system with an age- and gender-specific algorithm. Full article

(This article belongs to the Special Issue Tissue Optics)

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19 pages, 2358 KiB

Open AccessArticle

Ex Vivo Determination of Broadband Absorption and Effective Scattering Coefficients of Porcine Tissue

by Florian Bergmann, Florian Foschum, Leonie Marzel and Alwin Kienle

Photonics 2021, 8(9), 365; https://doi.org/10.3390/photonics8090365 - 31 Aug 2021

Cited by 13 | Viewed by 4100

Abstract

A novel approach for precise determination of the optical scattering and absorption properties of porcine tissue using an optimized integrating sphere setup was applied. Measurements on several sample types (skin, muscle, adipose tissue, bone, cartilage, brain) in the spectral range between 400 nm [...] Read more.

A novel approach for precise determination of the optical scattering and absorption properties of porcine tissue using an optimized integrating sphere setup was applied. Measurements on several sample types (skin, muscle, adipose tissue, bone, cartilage, brain) in the spectral range between 400 nm and 1400 nm were performed. Due to the heterogeneity of biological samples, measurements on different individual animals as well as on different sections for each sample type were carried out. For all samples, we used an index matching method to reduce surface roughness effects and to prevent dehydration. The derived absorption spectra were used to estimate the concentration of important tissue chromophores such as water, oxy- and deoxyhemoglobin, collagen and fat. Full article

(This article belongs to the Special Issue Tissue Optics)

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19 pages, 5248 KiB

Open AccessArticle

Evaluation of Three Iterative Algorithms for Phase Modulation Regarding Their Application in Concentrating Light Inside Biological Tissues for Laser Induced Photothermal Therapy

by João Guerreiro, Pedro Vieira and João M. P. Coelho

Photonics 2021, 8(9), 355; https://doi.org/10.3390/photonics8090355 - 27 Aug 2021

Cited by 1 | Viewed by 2054

Abstract

The focusing of light through turbid media like biological tissues is strongly hindered by the scattering of light which limits its safe practice and application in medicine. In order to control this phenomenon, we shaped the incident wavefront using three algorithms including a [...] Read more.

The focusing of light through turbid media like biological tissues is strongly hindered by the scattering of light which limits its safe practice and application in medicine. In order to control this phenomenon, we shaped the incident wavefront using three algorithms including a four-element division algorithm, a partitioning algorithm, and simulated annealing to control, iteratively, a spatial light modulator (SLM). We have tested two different convergence criteria to achieve a focal point inside a turbid environment, made up of a mixture of agar and milk, set to mimic a specific depth of human skin, and provide comparison results. A camera and a lens are used to visualize the focal area and give feedback information to the algorithms. A discussion on the use of these algorithms and convergence criteria is presented, being focused on its convergence time and performance. Depending on the algorithm and operational parameters, improvements of 29% to 46% of the irradiance in the region of interest were accomplished. Full article

(This article belongs to the Special Issue Tissue Optics)

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18 pages, 13159 KiB

Open AccessArticle

Spectroscopic Approach to Correction and Visualisation of Bright-Field Light Transmission Microscopy Biological Data

by Ganna Platonova, Dalibor Štys, Pavel Souček, Kirill Lonhus, Jan Valenta and Renata Rychtáriková

Photonics 2021, 8(8), 333; https://doi.org/10.3390/photonics8080333 - 13 Aug 2021

Cited by 5 | Viewed by 2210

Abstract

The most realistic information about a transparent sample such as a live cell can be obtained using bright-field light microscopy. Under high-intensity pulsing LED illumination, we captured a primary 12-bit-per-channel (bpc) response from an observed sample using a bright-field microscope equipped with a [...] Read more.

The most realistic information about a transparent sample such as a live cell can be obtained using bright-field light microscopy. Under high-intensity pulsing LED illumination, we captured a primary 12-bit-per-channel (bpc) response from an observed sample using a bright-field microscope equipped with a high-resolution (4872 × 3248) image sensor. In order to suppress data distortions originating from the light interactions with elements in the optical path, poor sensor reproduction (geometrical defects of the camera sensor and some peculiarities of sensor sensitivity), we propose a spectroscopic approach for the correction of these uncompressed 12 bpc data by simultaneous calibration of all parts of the experimental arrangement. Moreover, the final intensities of the corrected images are proportional to the photon fluxes detected by a camera sensor. It can be visualized in 8 bpc intensity depth after the Least Information Loss compression. Full article

(This article belongs to the Special Issue Tissue Optics)

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15 pages, 3481 KiB

Open AccessArticle

A Pixel-Dependent Finite Element Model for Spatial Frequency Domain Imaging Using NIRFAST

by Ben O. L. Mellors and Hamid Dehghani

Photonics 2021, 8(8), 310; https://doi.org/10.3390/photonics8080310 - 2 Aug 2021

Viewed by 2172

Abstract

Spatial frequency domain imaging (SFDI) utilizes the projection of spatially modulated light patterns upon biological tissues to obtain optical property maps for absorption and reduced scattering. Conventionally, both forward modeling and optical property recovery are performed using pixel-independent models, calculated via analytical solutions [...] Read more.

Spatial frequency domain imaging (SFDI) utilizes the projection of spatially modulated light patterns upon biological tissues to obtain optical property maps for absorption and reduced scattering. Conventionally, both forward modeling and optical property recovery are performed using pixel-independent models, calculated via analytical solutions or Monte-Carlo-based look-up tables, both assuming a homogenous medium. The resulting recovered maps are limited for samples of high heterogeneity, where the homogenous assumption is not valid. NIRFAST, a FEM-based image modeling and reconstruction tool, simulates complex heterogeneous tissue optical interactions for single and multiwavelength systems. Based on the diffusion equation, NIRFAST has been adapted to perform pixel-dependent forward modeling for SFDI. Validation is performed within the spatially resolved domain, along with homogenous structured illumination simulations, with a recovery error of <2%. Heterogeneity is introduced through cylindrical anomalies, varying size, depth and optical property values, with recovery errors of <10%, as observed across a variety of simulations. This work demonstrates the importance of pixel-dependent light interaction modeling for SFDI and its role in quantitative accuracy. Here, a full raw image SFDI modeling tool is presented for heterogeneous samples, providing a mechanism towards a pixel-dependent SFDI image modeling and parameter recovery system. Full article

(This article belongs to the Special Issue Tissue Optics)

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15 pages, 52068 KiB

Open AccessArticle

Spectroscopic Measurement of Methylene Blue Distribution in Organs and Tissues of Hamadryas Baboons during Oral Administration

by Elizaveta I. Kozlikina, Daria V. Pominova, Anastasia V. Ryabova, Kanamat T. Efendiev, Aleksei S. Skobeltsin, Natalia S. Rudenko, Olga G. Kulik, Evgeniya I. Muhametzyanova, Dzina D. Karal-ogly, Gleb A. Zhemerikin, Dmitry V. Bulgin, Artem A. Shiryaev, Igor V. Reshetov and Victor B. Loschenov

Photonics 2021, 8(8), 294; https://doi.org/10.3390/photonics8080294 - 24 Jul 2021

Cited by 3 | Viewed by 3246

Abstract

New research on Methylene Blue (MB), carried out in 2020, shows that it can be an effective antiviral drug as part of COVID-19 treatment. According to the research findings, MB has potential as a direct antiviral drug for the prevention and treatment of [...] Read more.

New research on Methylene Blue (MB), carried out in 2020, shows that it can be an effective antiviral drug as part of COVID-19 treatment. According to the research findings, MB has potential as a direct antiviral drug for the prevention and treatment of COVID-19 in the first stages of the disease. However, the MB accumulation by various types of tissues, as well as by immune cells, has not been previously studied. Therefore, the objective of this study was to obtain spectral data on the interstitial distribution of the administered drug in endothelial tissues in primates. The data on interstitial MB distribution obtained by spectroscopic measurement at both macro- and microlevels during oral administration to Hamadryas baboon individuals demonstrate that MB accumulates in mucous membranes of gastrointestinal tract and the tissues of the respiratory, cardiovascular, immune, and nervous systems. Additionally, it was found that MB was present in lung and brain myeloid cells in significant concentrations, which makes it potentially useful for protection from autoimmune response (cytokine storm) and as a tool for the correction of immunocompetent cells’ functional state during laser irradiation. Since the cytokine storm starts from monocytic cells during SARS-CoV-2 cellular damage and since tumor-associated macrophages can significantly alter tumor metabolism, accumulation of MB in these cells provides a reason to conclude that the immune response correction in COVID-19 patients and change in macrophages phenotype can be achieved by deactivation of inflammatory macrophages in tissues with MB using laser radiation of red spectral range. Full article

(This article belongs to the Special Issue Tissue Optics)

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9 pages, 3729 KiB

Open AccessArticle

Characterization of Ex Vivo Nonmelanoma Skin Tissue Using Raman Spectroscopy

by Hieu T. M. Nguyen, Yao Zhang, Austin J. Moy, Xu Feng, Katherine R. Sebastian, Jason S. Reichenberg, Matthew C. Fox, Mia K. Markey and James W. Tunnell

Photonics 2021, 8(7), 282; https://doi.org/10.3390/photonics8070282 - 16 Jul 2021

Cited by 7 | Viewed by 2475

Abstract

Raman spectroscopy has shown great potential in detecting nonmelanoma skin cancer accurately and quickly; however, little direct evidence exists on the sensitivity of measurements to the underlying anatomy. Here, we aimed to correlate Raman measurements directly to the underlying tissue anatomy. We acquired [...] Read more.

Raman spectroscopy has shown great potential in detecting nonmelanoma skin cancer accurately and quickly; however, little direct evidence exists on the sensitivity of measurements to the underlying anatomy. Here, we aimed to correlate Raman measurements directly to the underlying tissue anatomy. We acquired Raman spectra of ex vivo skin tissue from 25 patients undergoing Mohs surgery with a fiber probe. We utilized a previously developed biophysical model to extract key biomarkers in the skin from the Raman spectra. We then examined the correlations between the biomarkers and the major skin structures (including the dermis, sebaceous glands, hair follicles, fat, and two types of nonmelanoma skin cancer—basal cell carcinoma (BCC) and squamous cell carcinoma (SCC)). SCC had a significantly different concentration of keratin, collagen, and nucleic acid than normal structures, while ceramide differentiated BCC from normal structures. Our findings identified the key proteins, lipids, and nucleic acids that discriminate nonmelanoma tumors and healthy skin using Raman spectroscopy. These markers may be promising surgical guidance tools for detecting tumors in resection margins. Full article

(This article belongs to the Special Issue Tissue Optics)

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11 pages, 3231 KiB

Open AccessArticle

Elasticity Changes in the Crystalline Lens during Oxidative Damage and the Antioxidant Effect of Alpha-Lipoic Acid Measured by Optical Coherence Elastography

by Hongqiu Zhang, Manmohan Singh, Achuth Nair, Kirill V. Larin and Salavat R. Aglyamov

Photonics 2021, 8(6), 207; https://doi.org/10.3390/photonics8060207 - 8 Jun 2021

Cited by 10 | Viewed by 3855

Abstract

Age-related cataracts are one of the most prevalent causes of visual impairment around the world. Understanding the mechanisms of cataract development and progression is essential to enable early clinical diagnosis and treatment to preserve visual acuity. Reductive chemicals are potential medicines effective on [...] Read more.

Age-related cataracts are one of the most prevalent causes of visual impairment around the world. Understanding the mechanisms of cataract development and progression is essential to enable early clinical diagnosis and treatment to preserve visual acuity. Reductive chemicals are potential medicines effective on cataract treatment. In this work, we investigated the cataract-induced oxidative damage in the crystalline lens and a kind of reductant, α-lipoic acid (ALA), ability to reduce the damage. We created oxidative environment to investigate the relationship between the progression of oxidative cataract and lenticular biomechanical properties measured by dynamic optical coherence elastography in porcine crystalline lenses ex vivo. The efficacy of ALA to minimize the stiffening of the lens was also quantified. The results showed a significant increase in Young’s modulus of the lens due to the formation of the oxidative cataract. We found a statistically significant difference between Young’s modulus of the lenses stored in phosphate-buffered saline and ALA solution after incubation in H₂O₂ solution for 3 h (43.0 ± 9.0 kPa versus 20.7 ± 3.5 kPa, respectively). These results show that the lens stiffness increases during oxidative cataract formation, and ALA has the potential to reverse stiffening of the lens caused by oxidative damage. Full article

(This article belongs to the Special Issue Tissue Optics)

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Graphical abstract

14 pages, 2785 KiB

Open AccessArticle

Three-Dimensional Mapping of Retrograde Multi-Labeled Motor Neuron Columns in the Spinal Cord

by Jianyi Xu, Xiaofeng Yin, Yisong Qi, Bo Chen, Yusha Li, Peng Wan, Yingtao Yao, Dan Zhu, Baoguo Jiang and Tingting Yu

Photonics 2021, 8(5), 145; https://doi.org/10.3390/photonics8050145 - 28 Apr 2021

Cited by 2 | Viewed by 3963

Abstract

The quantification and distribution characteristics of spinal motor neurons play important roles in the study of spinal cord and peripheral nerve injury and repair. In most research, the sole retrograde labeling of each nerve or muscle could not simultaneously obtain the distributions of [...] Read more.

The quantification and distribution characteristics of spinal motor neurons play important roles in the study of spinal cord and peripheral nerve injury and repair. In most research, the sole retrograde labeling of each nerve or muscle could not simultaneously obtain the distributions of different motor neuron subpopulations. Therefore, it did not allow mapping of spatial relationships of different motor neuron columns for disclosing the functional relationship of different nerve branches. Here, we combined the multiple retrograde labeling, optical clearing, and imaging for three-dimensional (3D) visualization of motor neurons of multiple brachial plexus branches. After screening fluorescent tracers by the labeling feasibility of motor neurons and fluorescence compatibility with optical clearing, we performed mapping and quantification of the motor neurons of ulnar, median, and radial nerves in the spinal cord, then disclosed the relative spatial distribution among different neuronal subpopulations. This work will provide valuable mapping data for the understanding of the functional relationships among brachial plexus branches, hopefully facilitating the study of regeneration of axons and remodeling of motor neurons in peripheral nerve repair. Full article

(This article belongs to the Special Issue Tissue Optics)

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19 pages, 5572 KiB

Open AccessArticle

Compressional Optical Coherence Elastography of the Cornea

by Manmohan Singh, Achuth Nair, Salavat R. Aglyamov and Kirill V. Larin

Photonics 2021, 8(4), 111; https://doi.org/10.3390/photonics8040111 - 7 Apr 2021

Cited by 27 | Viewed by 4369

Abstract

Assessing the biomechanical properties of the cornea is crucial for detecting the onset and progression of eye diseases. In this work, we demonstrate the application of compression-based optical coherence elastography (OCE) to measure the biomechanical properties of the cornea under various conditions, including [...] Read more.

Assessing the biomechanical properties of the cornea is crucial for detecting the onset and progression of eye diseases. In this work, we demonstrate the application of compression-based optical coherence elastography (OCE) to measure the biomechanical properties of the cornea under various conditions, including validation in an in situ rabbit model and a demonstration of feasibility for in vivo measurements. Our results show a stark increase in the stiffness of the corneas as IOP was increased. Moreover, UV-A/riboflavin corneal collagen crosslinking (CXL) also dramatically increased the stiffness of the corneas. The results were consistent across 4 different scenarios (whole CXL in situ, partial CXL in situ, whole CXL in vivo, and partial CXL in vivo), emphasizing the reliability of compression OCE to measure corneal biomechanical properties and its potential for clinical applications. Full article

(This article belongs to the Special Issue Tissue Optics)

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Review

Jump to: Research

12 pages, 2743 KiB

Open AccessReview

Challenges in 3D Live Cell Imaging

by Herbert Schneckenburger and Verena Richter

Photonics 2021, 8(7), 275; https://doi.org/10.3390/photonics8070275 - 13 Jul 2021

Cited by 11 | Viewed by 4207

Abstract

A short overview on 3D live cell imaging is given. Relevant samples are described and various problems and challenges—including 3D imaging by optical sectioning, light scattering and phototoxicity—are addressed. Furthermore, enhanced methods of wide-field or laser scanning microscopy together with some relevant examples [...] Read more.

A short overview on 3D live cell imaging is given. Relevant samples are described and various problems and challenges—including 3D imaging by optical sectioning, light scattering and phototoxicity—are addressed. Furthermore, enhanced methods of wide-field or laser scanning microscopy together with some relevant examples and applications are summarized. In the future one may profit from a continuous increase in microscopic resolution, but also from molecular sensing techniques in the nanometer range using e.g., non-radiative energy transfer (FRET). Full article

(This article belongs to the Special Issue Tissue Optics)

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20 pages, 4609 KiB

Open AccessReview

Spatial-Frequency Domain Imaging: An Emerging Depth-Varying and Wide-Field Technique for Optical Property Measurement of Biological Tissues

by Zhizhong Sun, Dong Hu, Zhong Wang, Lijuan Xie and Yibin Ying

Photonics 2021, 8(5), 162; https://doi.org/10.3390/photonics8050162 - 12 May 2021

Cited by 13 | Viewed by 5057

Abstract

Measurement of optical properties is critical for understanding light-tissue interaction, properly interpreting measurement data, and gaining better knowledge of tissue physicochemical properties. However, conventional optical measuring techniques are limited in point measurement, which partly hinders the applications on characterizing spatial distribution and inhomogeneity [...] Read more.

Measurement of optical properties is critical for understanding light-tissue interaction, properly interpreting measurement data, and gaining better knowledge of tissue physicochemical properties. However, conventional optical measuring techniques are limited in point measurement, which partly hinders the applications on characterizing spatial distribution and inhomogeneity of optical properties of biological tissues. Spatial-frequency domain imaging (SFDI), as an emerging non-contact, depth-varying and wide-field optical imaging technique, is capable of measuring the optical properties in a wide field-of-view on a pixel-by-pixel basis. This review first describes the typical SFDI system and the principle for estimating optical properties using the SFDI technique. Then, the applications of SFDI in the fields of biomedicine, as well as food and agriculture, are reviewed, including burn assessment, skin tissue evaluation, tumor tissue detection, brain tissue monitoring, and quality evaluation of agro-products. Finally, a discussion on the challenges and future perspectives of SFDI for optical property estimation is presented. Full article

(This article belongs to the Special Issue Tissue Optics)

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