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Vu T, Klippel P, Canning AJ, Ma C, Zhang H, Kasatkina LA, Tang Y, Xia J, Verkhusha VV, Vo-Dinh T, Jing Y, Yao J. On the Importance of Low-Frequency Signals in Functional and Molecular Photoacoustic Computed Tomography. IEEE TRANSACTIONS ON MEDICAL IMAGING 2024; 43:771-783. [PMID: 37773898 PMCID: PMC10932611 DOI: 10.1109/tmi.2023.3320668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/01/2023]
Abstract
In photoacoustic computed tomography (PACT) with short-pulsed laser excitation, wideband acoustic signals are generated in biological tissues with frequencies related to the effective shapes and sizes of the optically absorbing targets. Low-frequency photoacoustic signal components correspond to slowly varying spatial features and are often omitted during imaging due to the limited detection bandwidth of the ultrasound transducer, or during image reconstruction as undesired background that degrades image contrast. Here we demonstrate that low-frequency photoacoustic signals, in fact, contain functional and molecular information, and can be used to enhance structural visibility, improve quantitative accuracy, and reduce spare-sampling artifacts. We provide an in-depth theoretical analysis of low-frequency signals in PACT, and experimentally evaluate their impact on several representative PACT applications, such as mapping temperature in photothermal treatment, measuring blood oxygenation in a hypoxia challenge, and detecting photoswitchable molecular probes in deep organs. Our results strongly suggest that low-frequency signals are important for functional and molecular PACT.
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2
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Sánchez-Ramos LL, Morales-Cruzado B, Pérez-Gutiérrez FG. Determination of tissue oxygen saturation by diffuse reflectance spectroscopy. JOURNAL OF BIOMEDICAL OPTICS 2023; 28:095002. [PMID: 37780203 PMCID: PMC10534074 DOI: 10.1117/1.jbo.28.9.095002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 09/09/2023] [Accepted: 09/13/2023] [Indexed: 10/03/2023]
Abstract
Significance Tissue oxygenation is a parameter that allows for determining the health status of human beings. In diabetic patients, it is particularly important to evaluate this parameter as an indicator of microcirculatory problems in the extremities. Aim We aim to obtain tissue oxygen saturation from diffuse reflectance measurements. Approach A computational algorithm to automate the methodology was implemented with the aim of establishing a medical diagnosis technique that is non-invasive and easy to apply and requires a short evaluation time. Tissue oxygen saturation measurements were performed on a group of volunteers to whom a vascular occlusion was applied. It was observed that, by increasing the applied pressure to the arm of each volunteer, the tissue oxygen saturation progressively decreased. Results The results indicate that the developed technique is an effective method for monitoring changes in blood hemodynamics in patients with some type of pathology in which tissue oxygenation is compromised. In addition, the expected behavior of tissue oxygen saturation during a vascular occlusion was obtained. Conclusions A methodology to obtain tissue oxygen saturation from diffuse reflectance measurements was successfully developed. It meets the necessary characteristics to be considered a technique for obtaining StO 2 because it can be applied in vivo and non-invasively and does not require a high computational cost; thus it is fast and capable of providing an objective and quantifiable evaluation.
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Affiliation(s)
| | - Beatriz Morales-Cruzado
- CONACYT-Universidad Autónoma de San Luis Potosí, Facultad de Ingeniería, San Luis Potosí, México
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Vu T, Klippel P, Canning AJ, Ma C, Zhang H, Kasatkina LA, Tang Y, Xia J, Verkhusha VV, Vo-Dinh T, Jing Y, Yao J. On the importance of low-frequency signals in functional and molecular photoacoustic computed tomography. ARXIV 2023:arXiv:2308.00870v1. [PMID: 37576129 PMCID: PMC10418541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
In photoacoustic computed tomography (PACT) with short-pulsed laser excitation, wideband acoustic signals are generated in biological tissues with frequencies related to the effective shapes and sizes of the optically absorbing targets. Low-frequency photoacoustic signal components correspond to slowly varying spatial features and are often omitted during imaging due to the limited detection bandwidth of the ultrasound transducer, or during image reconstruction as undesired background that degrades image contrast. Here we demonstrate that low-frequency photoacoustic signals, in fact, contain functional and molecular information, and can be used to enhance structural visibility, improve quantitative accuracy, and reduce spare-sampling artifacts. We provide an in-depth theoretical analysis of low-frequency signals in PACT, and experimentally evaluate their impact on several representative PACT applications, such as mapping temperature in photothermal treatment, measuring blood oxygenation in a hypoxia challenge, and detecting photoswitchable molecular probes in deep organs. Our results strongly suggest that low-frequency signals are important for functional and molecular PACT.
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Affiliation(s)
- Tri Vu
- Photoacoustic Imaging Laboratory, Duke University, Durham, NC 27708 USA
| | - Paul Klippel
- Graduate Program in Acoustics, Penn State University, University Park, PA 16802
| | - Aidan J Canning
- Department of Biomedical Engineering, Department of Chemistry, and Fitzpatrick Institute of Photonics, Duke University, Durham, NC 27708
| | - Chenshuo Ma
- Photoacoustic Imaging Laboratory, Duke University, Durham, NC 27708 USA
| | - Huijuan Zhang
- Department of Biomedical Engineering, State University of New York, Buffalo, NY 14260
| | - Ludmila A Kasatkina
- Department of Genetics and Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Yuqi Tang
- Photoacoustic Imaging Laboratory, Duke University, Durham, NC 27708 USA
| | - Jun Xia
- Department of Biomedical Engineering, State University of New York, Buffalo, NY 14260
| | - Vladislav V Verkhusha
- Department of Genetics and Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Tuan Vo-Dinh
- Department of Biomedical Engineering, Department of Chemistry, and Fitzpatrick Institute of Photonics, Duke University, Durham, NC 27708
| | - Yun Jing
- Graduate Program in Acoustics, Penn State University, University Park, PA 16802
| | - Junjie Yao
- Photoacoustic Imaging Laboratory, Duke University, Durham, NC 27708 USA
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Helical Nanostructures of Ferroelectric Liquid Crystals as Fast Phase Retarders for Spectral Information Extraction Devices: A Comparison with the Nematic Liquid Crystal Phase Retarders. MATERIALS 2021; 14:ma14195540. [PMID: 34639937 PMCID: PMC8509210 DOI: 10.3390/ma14195540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 09/06/2021] [Accepted: 09/14/2021] [Indexed: 11/17/2022]
Abstract
Extraction of spectral information using liquid crystal (LC) retarders has recently become a topic of great interest because of its importance for creating hyper- and multispectral images in a compact and inexpensive way. However, this method of hyperspectral imaging requires thick LC-layer retarders (50 µm-100 µm and above) to obtain spectral modulation signals for reliable signal reconstruction. This makes the device extremely slow in the case of nematic LCs (NLCs), since the response time of NLCs increases proportionally to the square of the LC-layer thickness, which excludes fast dynamic processes monitoring. In this paper, we explore two approaches for solving the speed problem: the first is based on the use of faster nanospiral ferroelectric liquid crystals as an alternative to NLCs, and the second is based on using a passive multiband filter and focuses on multispectral extraction rather than hyperspectral. A detailed comparative study of nematic and ferroelectric devices is presented. The study is carried out using a 9-spectral bands passive spectral filter, covering the visible and near-infrared ranges. We propose the concept of multispectral rather than hyperspectral extraction, where a small number of wavelengths are sufficient for specific applications.
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5
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He Q, Wang RK. Analysis of skin morphological features and real-time monitoring using snapshot hyperspectral imaging. BIOMEDICAL OPTICS EXPRESS 2019; 10:5625-5638. [PMID: 31799035 PMCID: PMC6865098 DOI: 10.1364/boe.10.005625] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 09/11/2019] [Accepted: 09/20/2019] [Indexed: 05/07/2023]
Abstract
We propose a snapshot hyperspectral imaging system and methods for skin morphological feature analysis and real-time monitoring of skin activities. The analysis method includes a strategy using weighted subtractions between sub-channel images to extract absorption information due to specific chromophores within skin tissue, for example hemoglobin and melanin. Based on morphological analysis results, we carry out real-time monitoring of the skin features to verify the ability of this method to provide temporal responses of the skin tissue activities, which is experimentally shown to be useful in the measurement of heartrate, monitoring of the tissue recovery after a body exercise, and studying of the tissue response due to a vascular occlusion. Compared to conventional multispectral imaging system, the proposed system improves the device simplicity and is immune to motion artifacts. Coupled with the extraction algorithms, the hyperspectral imaging promises a robust skin assessment tool with abilities for qualitative visualization and potentially quantitative analysis of skin features, useful in the applications of cosmetics and clinical dermatology.
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Affiliation(s)
- Qinghua He
- Department of Bioengineering, University of Washington, Seattle, Washington 98105, USA
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, Washington 98105, USA
- Department of Ophthalmology, University of Washington, Seattle, Washington 98109, USA
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6
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Ali Shah SA, Laude A, Faye I, Tang TB. Automated microaneurysm detection in diabetic retinopathy using curvelet transform. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:101404. [PMID: 26868326 DOI: 10.1117/1.jbo.21.10.101404] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 01/18/2016] [Indexed: 06/05/2023]
Abstract
Microaneurysms (MAs) are known to be the early signs of diabetic retinopathy (DR). An automated MA detection system based on curvelet transform is proposed for color fundus image analysis. Candidates of MA were extracted in two parallel steps. In step one, blood vessels were removed from preprocessed green band image and preliminary MA candidates were selected by local thresholding technique. In step two, based on statistical features, the image background was estimated. The results from the two steps allowed us to identify preliminary MA candidates which were also present in the image foreground. A collection set of features was fed to a rule-based classifier to divide the candidates into MAs and non-MAs. The proposed system was tested with Retinopathy Online Challenge database. The automated system detected 162 MAs out of 336, thus achieved a sensitivity of 48.21% with 65 false positives per image. Counting MA is a means to measure the progression of DR. Hence, the proposed system may be deployed to monitor the progression of DR at early stage in population studies.
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Affiliation(s)
- Syed Ayaz Ali Shah
- Universiti Teknologi PETRONAS, Department of Electrical and Electronic Engineering, Centre for Intelligent Signal and Imaging Research, Bandar Seri Iskandar, Perak 32610, Malaysia
| | - Augustinus Laude
- National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore 308433, Singapore
| | - Ibrahima Faye
- Universiti Teknologi PETRONAS, Department of Fundamental and Applied Sciences, Centre for Intelligent Signal and Imaging Research, Bandar Seri Iskandar, Perak 32610, Malaysia
| | - Tong Boon Tang
- Universiti Teknologi PETRONAS, Department of Electrical and Electronic Engineering, Centre for Intelligent Signal and Imaging Research, Bandar Seri Iskandar, Perak 32610, Malaysia
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7
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Ehler M, Dobrosotskaya J, Cunningham D, Wong WT, Chew EY, Czaja W, Bonner RF. Modeling Photo-Bleaching Kinetics to Create High Resolution Maps of Rod Rhodopsin in the Human Retina. PLoS One 2015. [PMID: 26196397 PMCID: PMC4510609 DOI: 10.1371/journal.pone.0131881] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
We introduce and describe a novel non-invasive in-vivo method for mapping local rod rhodopsin distribution in the human retina over a 30-degree field. Our approach is based on analyzing the brightening of detected lipofuscin autofluorescence within small pixel clusters in registered imaging sequences taken with a commercial 488nm confocal scanning laser ophthalmoscope (cSLO) over a 1 minute period. We modeled the kinetics of rhodopsin bleaching by applying variational optimization techniques from applied mathematics. The physical model and the numerical analysis with its implementation are outlined in detail. This new technique enables the creation of spatial maps of the retinal rhodopsin and retinal pigment epithelium (RPE) bisretinoid distribution with an ≈ 50μm resolution.
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Affiliation(s)
- Martin Ehler
- Faculty of Mathematics, University of Vienna, Vienna, Austria
- * E-mail:
| | - Julia Dobrosotskaya
- Department of Mathematics, Applied Mathematics, and Statistics, Case Western Reserve University, Cleveland, OH, United States of America
| | - Denise Cunningham
- Office of the Clinical Director, National Eye Institute, National Institutes of Health, Bethesda, MD, United States of America
| | - Wai T. Wong
- Unit on Neuron-Glia Interactions, National Eye Institute, National Institutes of Health, Bethesda, MD, United States of America
| | - Emily Y. Chew
- Division of Epidemiology and Clinical Applications, National Eye Institute, National Institutes of Health, Bethesda, MD, United States of America
| | - Wojtek Czaja
- Department of Mathematics, University of Maryland, College Park, MD, United States of America
| | - Robert F. Bonner
- Section on Medical Biophysics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States of America
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8
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Martín-Mateos P, Crespo-Garcia S, Ruiz-Llata M, Lopez-Fernandez JR, Jorcano JL, Del Rio M, Larcher F, Acedo P. Remote diffuse reflectance spectroscopy sensor for tissue engineering monitoring based on blind signal separation. BIOMEDICAL OPTICS EXPRESS 2014; 5:3231-7. [PMID: 25401034 PMCID: PMC4230878 DOI: 10.1364/boe.5.003231] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 08/11/2014] [Accepted: 08/22/2014] [Indexed: 05/26/2023]
Abstract
In this study the first results on evaluation and assessment of grafted bioengineered skin substitutes using an optical Diffuse Reflectance Spectroscopy (DRS) system with a remote optical probe are shown. The proposed system is able to detect early vascularization of skin substitutes expressing the Vascular Endothelial Growth Factor (VEGF) protein compared to normal grafts, even though devitalized skin is used to protect the grafts. Given the particularities of the biological problem, data analysis is performed using two Blind Signal Separation (BSS) methods: Principal Component Analysis (PCA) and Independent Component Analysis (ICA). These preliminary results are the first step towards point-of-care diagnostics for skin implants early assessment.
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Affiliation(s)
- Pedro Martín-Mateos
- Department of Electronics Technology, Universidad Carlos III de Madrid, Leganes, Madrid 28911, Spain
| | - Sergio Crespo-Garcia
- Epithelial Biomedicine Division, CIEMAT, Avenida Complutense 40, Madrid 28040, Spain and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Marta Ruiz-Llata
- Department of Electronics Technology, Universidad Carlos III de Madrid, Leganes, Madrid 28911, Spain
| | | | - José Luis Jorcano
- Epithelial Biomedicine Division, CIEMAT, Avenida Complutense 40, Madrid 28040, Spain and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain ; Department of Bioengineering, Universidad Carlos III de Madrid, Leganes, Madrid 28911, Spain
| | - Marcela Del Rio
- Epithelial Biomedicine Division, CIEMAT, Avenida Complutense 40, Madrid 28040, Spain and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain ; Department of Bioengineering, Universidad Carlos III de Madrid, Leganes, Madrid 28911, Spain
| | - Fernando Larcher
- Epithelial Biomedicine Division, CIEMAT, Avenida Complutense 40, Madrid 28040, Spain and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain ; Department of Bioengineering, Universidad Carlos III de Madrid, Leganes, Madrid 28911, Spain
| | - Pablo Acedo
- Department of Electronics Technology, Universidad Carlos III de Madrid, Leganes, Madrid 28911, Spain
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9
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Kainerstorfer JM, Polizzotto MN, Uldrick TS, Rahman R, Hassan M, Najafizadeh L, Ardeshirpour Y, Wyvill KM, Aleman K, Smith PD, Yarchoan R, Gandjbakhche AH. Evaluation of non-invasive multispectral imaging as a tool for measuring the effect of systemic therapy in Kaposi sarcoma. PLoS One 2013; 8:e83887. [PMID: 24386302 PMCID: PMC3873970 DOI: 10.1371/journal.pone.0083887] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Accepted: 11/09/2013] [Indexed: 11/18/2022] Open
Abstract
Diffuse multi-spectral imaging has been evaluated as a potential non-invasive marker of tumor response. Multi-spectral images of Kaposi sarcoma skin lesions were taken over the course of treatment, and blood volume and oxygenation concentration maps were obtained through principal component analysis (PCA) of the data. These images were compared with clinical and pathological responses determined by conventional means. We demonstrate that cutaneous lesions have increased blood volume concentration and that changes in this parameter are a reliable indicator of treatment efficacy, differentiating responders and non-responders. Blood volume decreased by at least 20% in all lesions that responded by clinical criteria and increased in the two lesions that did not respond clinically. Responses as assessed by multi-spectral imaging also generally correlated with overall patient clinical response assessment, were often detectable earlier in the course of therapy, and are less subject to observer variability than conventional clinical assessment. Tissue oxygenation was more variable, with lesions often showing decreased oxygenation in the center surrounded by a zone of increased oxygenation. This technique could potentially be a clinically useful supplement to existing response assessment in KS, providing an early, quantitative, and non-invasive marker of treatment effect.
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Affiliation(s)
- Jana M. Kainerstorfer
- Section on Analytical and Functional Biophotonics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Mark N. Polizzotto
- HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Thomas S. Uldrick
- HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Rafa Rahman
- Section on Analytical and Functional Biophotonics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Moinuddin Hassan
- Section on Analytical and Functional Biophotonics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Laleh Najafizadeh
- Section on Analytical and Functional Biophotonics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Yasaman Ardeshirpour
- Section on Analytical and Functional Biophotonics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Kathleen M. Wyvill
- HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Karen Aleman
- HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Paul D. Smith
- Biomedical Instrumentation and Multiscale Imaging Section, Laboratory of Cellular Imaging and Macromolecular Biophysics, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Robert Yarchoan
- HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Amir H. Gandjbakhche
- Section on Analytical and Functional Biophotonics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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10
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Dasgeb B, Kainerstorfer J, Mehregan D, Van Vreede A, Gandjbakhche A. An introduction to primary skin imaging. Int J Dermatol 2013; 52:1319-30. [PMID: 23879559 DOI: 10.1111/ijd.12048] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 08/26/2012] [Accepted: 10/09/2012] [Indexed: 11/30/2022]
Abstract
Dermatology is a field in which clinical examination is heavily relied upon for diagnosis. When required, a tissue biopsy may also be performed to confirm the diagnosis. Recent advances in imaging techniques have been applied to cutaneous lesions to improve diagnostic accuracy without the need for biopsy. These new imaging techniques are reviewed for their developing role in dermatology.
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Affiliation(s)
- Bahar Dasgeb
- Dermatology Department, Sloan Memorial Kettering Cancer Center, New York, NY, USA; Analytical and Stochastic Biomedical Physics Section, NICHD, NIH, Bethesda, MD, USA
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11
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Czaja W, Ehler M. Schroedinger Eigenmaps for the analysis of biomedical data. IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE 2013; 35:1274-1280. [PMID: 23520264 DOI: 10.1109/tpami.2012.270] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We introduce Schroedinger Eigenmaps (SE), a new semi-supervised manifold learning and recovery technique. This method is based on an implementation of graph Schroedinger operators with appropriately constructed barrier potentials as carriers of labeled information. We use our approach for the analysis of standard biomedical datasets and new multispectral retinal images.
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Affiliation(s)
- Wojciech Czaja
- Department of Mathematics, University of Maryland, College Park, MD 20742, USA.
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12
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Abstract
Diffusion geometry techniques are useful to classify patterns and visualize high-dimensional datasets. Building upon ideas from diffusion geometry, we outline our mathematical foundations for learning a function on high-dimension biomedical data in a local fashion from training data. Our approach is based on a localized summation kernel, and we verify the computational performance by means of exact approximation rates. After these theoretical results, we apply our scheme to learn early disease stages in standard and new biomedical datasets.
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Affiliation(s)
- M Ehler
- Helmholtz Zentrum München, Institute of Biomathematics and Biometry, Ingolstädter Landstrasse 1, D-85764 Neuherberg, Germany.
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13
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Medina JM, Pereira LM, Correia HT, Nascimento SMC. Hyperspectral optical imaging of human iris in vivo: characteristics of reflectance spectra. JOURNAL OF BIOMEDICAL OPTICS 2011; 16:076001. [PMID: 21806262 DOI: 10.1117/1.3595710] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report a hyperspectral imaging system to measure the reflectance spectra of real human irises with high spatial resolution. A set of ocular prosthesis was used as the control condition. Reflectance data were decorrelated by the principal-component analysis. The main conclusion is that spectral complexity of the human iris is considerable: between 9 and 11 principal components are necessary to account for 99% of the cumulative variance in human irises. Correcting image misalignments associated with spontaneous ocular movements did not influence this result. The data also suggests a correlation between the first principal component and different levels of melanin present in the irises. It was also found that although the spectral characteristics of the first five principal components were not affected by the radial and angular position of the selected iridal areas, they affect the higher-order ones, suggesting a possible influence of the iris texture. The results show that hyperspectral imaging in the iris, together with adequate spectroscopic analyses provide more information than conventional colorimetric methods, making hyperspectral imaging suitable for the characterization of melanin and the noninvasive diagnosis of ocular diseases and iris color.
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Affiliation(s)
- José M Medina
- University of Minho, Centre of Physics, Department of Physics, Campus de Gualtar, 4710-057, Braga, Portugal.
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14
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Kainerstorfer JM, Riley JD, Ehler M, Najafizadeh L, Amyot F, Hassan M, Pursley R, Demos SG, Chernomordik V, Pircher M, Smith PD, Hitzenberger CK, Gandjbakhche AH. Quantitative principal component model for skin chromophore mapping using multi-spectral images and spatial priors. BIOMEDICAL OPTICS EXPRESS 2011; 2:1040-58. [PMID: 21559118 PMCID: PMC3087563 DOI: 10.1364/boe.2.001040] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 03/29/2011] [Accepted: 03/29/2011] [Indexed: 05/06/2023]
Abstract
We describe a novel reconstruction algorithm based on Principal Component Analysis (PCA) applied to multi-spectral imaging data. Using numerical phantoms, based on a two layered skin model developed previously, we found analytical expressions, which convert qualitative PCA results into quantitative blood volume and oxygenation values, assuming the epidermal thickness to be known. We also evaluate the limits of accuracy of this method when the value of the epidermal thickness is not known. We show that blood volume can reliably be extracted (less than 6% error) even if the assumed thickness deviates 0.04mm from the actual value, whereas the error in blood oxygenation can be as large as 25% for the same deviation in thickness. This PCA based reconstruction was found to extract blood volume and blood oxygenation with less than 8% error, if the underlying structure is known. We then apply the method to in vivo multi-spectral images from a healthy volunteer's lower forearm, complemented by images of the same area using Optical Coherence Tomography (OCT) for measuring the epidermal thickness. Reconstruction of the imaging results using a two layered analytical skin model was compared to PCA based reconstruction results. A point wise correlation was found, showing the proof of principle of using PCA based reconstruction for blood volume and oxygenation extraction.
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Affiliation(s)
- Jana M. Kainerstorfer
- National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Program on Pediatric Imaging and Tissue Sciences, Section on Analytical and Functional Biophotonics, Bethesda, MD, 20892
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Waehringer Str. 13, 1090 Vienna, Austria
| | - Jason D. Riley
- National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Program on Pediatric Imaging and Tissue Sciences, Section on Analytical and Functional Biophotonics, Bethesda, MD, 20892
| | - Martin Ehler
- National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Program in Physical Biology, Laboratory of Integrative and Medical Biophysics, Section on Medical Biophysics, Bethesda, MD, 20892
| | - Laleh Najafizadeh
- National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Program on Pediatric Imaging and Tissue Sciences, Section on Analytical and Functional Biophotonics, Bethesda, MD, 20892
- Henry M. Jackson Foundation, Rockville, MD, 20852
| | - Franck Amyot
- National Institutes of Health, National Institutes of Neurological Disorders and Stroke, Clinical Neuroscience Program, Bethesda, MD, 20892
| | - Moinuddin Hassan
- National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Program on Pediatric Imaging and Tissue Sciences, Section on Analytical and Functional Biophotonics, Bethesda, MD, 20892
| | - Randall Pursley
- National Institutes of Health, Center for Information Technology, Division of Computational Bioscience, Signal Processing and Instrumentation Section, Bethesda, MD, 20892
| | | | - Victor Chernomordik
- National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Program on Pediatric Imaging and Tissue Sciences, Section on Analytical and Functional Biophotonics, Bethesda, MD, 20892
| | - Michael Pircher
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Waehringer Str. 13, 1090 Vienna, Austria
| | - Paul D. Smith
- National Institutes of Health, National Institute of Biomedical Imaging and Bioengineering, Laboratory of Cellular Imaging and Macromolecular Biophysics, Biomedical Instrumentation and Multiscale Imaging Section, Bethesda, MD, 20892
| | - Christoph K. Hitzenberger
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Waehringer Str. 13, 1090 Vienna, Austria
| | - Amir H. Gandjbakhche
- National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Program on Pediatric Imaging and Tissue Sciences, Section on Analytical and Functional Biophotonics, Bethesda, MD, 20892
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