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Charpignon ML, Carrel A, Jiang Y, Kwaga T, Cantada B, Hyslop T, Cox CE, Haines K, Koomson V, Dumas G, Morley M, Dunn J, Ian Wong AK. Going beyond the means: Exploring the role of bias from digital determinants of health in technologies. PLOS DIGITAL HEALTH 2023; 2:e0000244. [PMID: 37824494 PMCID: PMC10569586 DOI: 10.1371/journal.pdig.0000244] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
BACKGROUND In light of recent retrospective studies revealing evidence of disparities in access to medical technology and of bias in measurements, this narrative review assesses digital determinants of health (DDoH) in both technologies and medical formulae that demonstrate either evidence of bias or suboptimal performance, identifies potential mechanisms behind such bias, and proposes potential methods or avenues that can guide future efforts to address these disparities. APPROACH Mechanisms are broadly grouped into physical and biological biases (e.g., pulse oximetry, non-contact infrared thermometry [NCIT]), interaction of human factors and cultural practices (e.g., electroencephalography [EEG]), and interpretation bias (e.g, pulmonary function tests [PFT], optical coherence tomography [OCT], and Humphrey visual field [HVF] testing). This review scope specifically excludes technologies incorporating artificial intelligence and machine learning. For each technology, we identify both clinical and research recommendations. CONCLUSIONS Many of the DDoH mechanisms encountered in medical technologies and formulae result in lower accuracy or lower validity when applied to patients outside the initial scope of development or validation. Our clinical recommendations caution clinical users in completely trusting result validity and suggest correlating with other measurement modalities robust to the DDoH mechanism (e.g., arterial blood gas for pulse oximetry, core temperatures for NCIT). Our research recommendations suggest not only increasing diversity in development and validation, but also awareness in the modalities of diversity required (e.g., skin pigmentation for pulse oximetry but skin pigmentation and sex/hormonal variation for NCIT). By increasing diversity that better reflects patients in all scenarios of use, we can mitigate DDoH mechanisms and increase trust and validity in clinical practice and research.
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Affiliation(s)
- Marie-Laure Charpignon
- Massachusetts Institute of Technology; Institute for Data, Systems, and Society; Laboratory for Information and Decision Systems, Boston, Massachusetts, United States of America
| | - Adrien Carrel
- CentraleSupélec, Université Paris-Saclay, Gif-sur-Yvette, France
- Imperial College London, London, United Kingdom
| | - Yihang Jiang
- Duke University, Pratt School of Engineering, Department of Biomedical Engineering, Durham, North Carolina, United States of America
| | - Teddy Kwaga
- Mbarara University of Science and Technology, Department of Ophthalmology, Mbarara, Uganda
| | - Beatriz Cantada
- Massachusetts Institute of Technology; Institute Community and Equity Office, Boston, Massachusetts, United States of America
| | - Terry Hyslop
- Duke University, Department of Biostatistics and Bioinformatics, Durham, North Carolina, United States of America
| | - Christopher E. Cox
- Duke University, Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Durham, North Carolina, United States of America
| | - Krista Haines
- Duke University, Department of Surgery, Durham, North Carolina, United States of America
| | - Valencia Koomson
- Tufts University, Department of Electrical and Computer Engineering, Boston, Massachusetts, United States of America
| | - Guillaume Dumas
- CHU Sainte-Justine Research Center, Department of Psychiatry, Université de Montréal, Montréal, Quebec, Canada
- Mila–Quebec AI Institute, University of Montreal, Montréal, Quebec, Canada
| | - Michael Morley
- Ophthalmic Consultants of Boston, Boston, Massachusetts, United States of America
- Assistant Clinical Professor of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jessilyn Dunn
- Duke University, Pratt School of Engineering, Department of Biomedical Engineering, Durham, North Carolina, United States of America
- Duke University, Department of Biostatistics and Bioinformatics, Durham, North Carolina, United States of America
| | - An-Kwok Ian Wong
- Duke University, Department of Biostatistics and Bioinformatics, Durham, North Carolina, United States of America
- Duke University, Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Durham, North Carolina, United States of America
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2
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Efendiev K, Alekseeva P, Shiryaev A, Voitova A, Linkov K, Pisareva T, Reshetov I, Loschenov V. Near-infrared phototheranostics of tumors with protoporphyrin IX and chlorin e6 photosensitizers. Photodiagnosis Photodyn Ther 2023; 42:103566. [PMID: 37059163 DOI: 10.1016/j.pdpdt.2023.103566] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 04/06/2023] [Accepted: 04/11/2023] [Indexed: 04/16/2023]
Abstract
BACKGROUND The study aims to develop a method for phototheranostics of tumors in the near-infrared (NIR) range using protoporphyrin IX (PpIX) and chlorin e6 (Ce6) photosensitizers (PSs) MATERIALS AND METHODS: Phototheranostics includes spectral fluorescence diagnostics of PS distribution and photodynamic therapy (PDT) using a single laser in the red spectral range. PpIX and Ce6 fluorescence were registered in the NIR range. PpIX and Ce6 photobleaching was determined during PDT by the change in PS fluorescence. NIR phototheranostics with PpIX and Ce6 were performed on optical phantoms and tumors of patients with oral leukoplakia and basal cell carcinoma. RESULTS NIR spectral fluorescence diagnostics of optical phantoms with PpIX or Ce6 is possible when fluorescence is excited by 635 or 660 nm lasers. Fluorescence intensity of PpIX and Ce6 was measured in the range of 725-780 nm. The highest values of signal-to-noise in the case of phantoms with PpIX were observed at λexc=635 nm, and for phantoms with Ce6 at λexc=660 nm. NIR phototheranostics provides the detection of tumor tissues with PpIX or Ce6 accumulation. The PSs photobleaching in the tumor during PDT occurs according to a bi-exponential law. CONCLUSION Phototheranostics of tumors containing PpIX or Ce6 allows fluorescent monitoring of PS distribution in the NIR range and measuring PSs photobleaching during light exposure that provides personalization of the photodynamic exposure duration to deeper tumors. Using a single laser for fluorescence diagnostics and PDT reduces patient treatment time.
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Affiliation(s)
- Kanamat Efendiev
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia; Department of Laser Micro-, Nano-, and Biotechnology, Institute of Engineering Physics for Biomedicine, National Research Nuclear University "MEPhI", 115409 Moscow, Russia.
| | - Polina Alekseeva
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia.
| | - Artem Shiryaev
- Sechenov First Moscow State Medical University, Ministry of Health of the Russian Federation, Levshin Institute of Cluster Oncology, University Clinical Hospital No.1, 119435 Moscow, Russia.
| | | | - Kirill Linkov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia.
| | - Tatiana Pisareva
- Sechenov First Moscow State Medical University, Ministry of Health of the Russian Federation, Levshin Institute of Cluster Oncology, University Clinical Hospital No.1, 119435 Moscow, Russia.
| | - Igor Reshetov
- Sechenov First Moscow State Medical University, Ministry of Health of the Russian Federation, Levshin Institute of Cluster Oncology, University Clinical Hospital No.1, 119435 Moscow, Russia.
| | - Victor Loschenov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 119991 Moscow, Russia; Department of Laser Micro-, Nano-, and Biotechnology, Institute of Engineering Physics for Biomedicine, National Research Nuclear University "MEPhI", 115409 Moscow, Russia.
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3
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Webb EK, Etter JA, Kwasa JA. Addressing racial and phenotypic bias in human neuroscience methods. Nat Neurosci 2022; 25:410-414. [PMID: 35383334 PMCID: PMC9138180 DOI: 10.1038/s41593-022-01046-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 03/01/2022] [Indexed: 11/09/2022]
Abstract
Despite their premise of objectivity, neuroscience tools for physiological data collection, such as electroencephalography and functional near-infrared spectroscopy, introduce racial bias into studies by excluding individuals on the basis of phenotypic differences in hair type and skin pigmentation. Furthermore, at least one methodology-electrodermal activity recording (skin conductance responses)-may be influenced not only by potential phenotypic differences but also by negative psychological effects stemming from the lived experience of racism. Here we situate these issues within structural injustice, urge researchers to challenge racism in their scientific work and propose procedures and changes that may lead to more equitable science.
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Affiliation(s)
- E Kate Webb
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA.
- Division of Depression and Anxiety, McLean Hospital, Belmont, MA, USA.
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA.
| | - J Arthur Etter
- Department of Philosophy, McGill University, Montréal, QC, Canada
| | - Jasmine A Kwasa
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA, USA
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4
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Adnan A, Yaroslavsky AN, Carroll JD, Selting W, Juliano AF, London WB, Sonis ST, Duncan CN, Treister NS. The Path to an Evidence-Based Treatment Protocol for Extraoral Photobiomodulation Therapy for the Prevention of Oral Mucositis. FRONTIERS IN ORAL HEALTH 2022; 2:689386. [PMID: 35048034 PMCID: PMC8757848 DOI: 10.3389/froh.2021.689386] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 06/22/2021] [Indexed: 12/15/2022] Open
Abstract
Oral mucositis is a painful complication of hematopoietic stem cell transplantation for which photobiomodulation therapy (PBMT) is a safe and effective intervention. Extraoral delivery of PBMT has clinical advantages over intraoral delivery but requires additional dosimetric considerations due to the external tissue layers through which the light must propagate before reaching the oral mucosa. Additionally, to date there has been no dose modeling study, a task essential to developing a justified treatment protocol. We review here some of the complexities surrounding extraoral photobiomodulation therapy and offer that may help guide researchers toward an evidence-based treatment protocol for the prevention of oral mucositis.
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Affiliation(s)
- Ather Adnan
- Texas A&M University Health Science Center, College of Medicine, Houston, TX, United States
| | - Anna N Yaroslavsky
- Advanced Biophotonics Laboratory, Department of Physics and Applied Physics, University of Massachusetts Lowell, Lowell, MA, United States.,Department of Dermatology, Massachusetts General Hospital, Boston, MA, United States
| | | | - Wayne Selting
- Department of Surgical Science and Integrated Diagnostics, University of Genoa, Genoa, Italy
| | - Amy F Juliano
- Department of Radiology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, United States
| | - Wendy B London
- Department of Pediatrics, Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Harvard Medical School, Boston, MA, United States
| | - Stephen T Sonis
- Department of Surgery, Divisions of Oral Medicine and Dentistry, Brigham and Women's Hospital and the Dana-Farber Cancer Institute, Boston, MA, United States.,Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, United States.,Biomodels LLC., Waltham, MA, United States
| | - Christine N Duncan
- Department of Pediatrics, Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Harvard Medical School, Boston, MA, United States
| | - Nathaniel S Treister
- Department of Surgery, Divisions of Oral Medicine and Dentistry, Brigham and Women's Hospital and the Dana-Farber Cancer Institute, Boston, MA, United States.,Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, United States
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Bachir W, Abo Dargham F. Feasibility of 830 nm laser imaging for vein localization in dark skin tissue-mimicking phantoms. Phys Eng Sci Med 2022; 45:135-142. [PMID: 34982404 DOI: 10.1007/s13246-021-01096-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 12/25/2021] [Indexed: 10/19/2022]
Abstract
Accessing blood vessels by medical professionals has been a challenge in healthcare centers worldwide. The main objective of this work is to investigate the localization of blood vessels in dark skin based on near infrared laser imaging. An 830 nm diode laser was used as a light source to irradiate dark skin mimicking optical phantoms. Phantoms were constructed to simulate dark skin with embedded polymer tubes filled with human blood to mimic subcutaneous veins. Appropriate image processing techniques were also used to enhance the detection and depth resolved differentiation of the vein phantoms. Results show that a linear regression model can represent the relation between the grey level in subcutaneous vein images and the depth of vessels down to 3 mm or deeper (n = 15, R2 = 0.88, P < 0.001). The effect of laser power on the system performance is also discussed. Analysis of the collected images demonstrates the feasibility of 830 nm laser imaging for differentiating vein depths under dark skin surface. The proposed method would enhance the localization of invisible subcutaneous veins. This, in turn, would further improve the success rate of related medical procedures such as blood sampling, drawing, in the dark skin population.
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Affiliation(s)
- Wesam Bachir
- Biomedical Photonics Laboratory, Higher Institute for Laser Research and Applications, Damascus University, Damascus, Syria. .,Faculty of Informatics Engineering, Al-Sham Private University, Damascus, Syria.
| | - Farah Abo Dargham
- Biomedical Photonics Laboratory, Higher Institute for Laser Research and Applications, Damascus University, Damascus, Syria.,Faculty of Informatics Engineering, Aljazeera Private University, Damascus, Syria
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Ganti V, Carek AM, Jung H, Srivatsa AV, Cherry D, Johnson LN, Inan OT. Enabling Wearable Pulse Transit Time-Based Blood Pressure Estimation for Medically Underserved Areas and Health Equity: Comprehensive Evaluation Study. JMIR Mhealth Uhealth 2021; 9:e27466. [PMID: 34338646 PMCID: PMC8369375 DOI: 10.2196/27466] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/10/2021] [Accepted: 05/10/2021] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Noninvasive and cuffless approaches to monitor blood pressure (BP), in light of their convenience and accuracy, have paved the way toward remote screening and management of hypertension. However, existing noninvasive methodologies, which operate on mechanical, electrical, and optical sensing modalities, have not been thoroughly evaluated in demographically and racially diverse populations. Thus, the potential accuracy of these technologies in populations where they could have the greatest impact has not been sufficiently addressed. This presents challenges in clinical translation due to concerns about perpetuating existing health disparities. OBJECTIVE In this paper, we aim to present findings on the feasibility of a cuffless, wrist-worn, pulse transit time (PTT)-based device for monitoring BP in a diverse population. METHODS We recruited a diverse population through a collaborative effort with a nonprofit organization working with medically underserved areas in Georgia. We used our custom, multimodal, wrist-worn device to measure the PTT through seismocardiography, as the proximal timing reference, and photoplethysmography, as the distal timing reference. In addition, we created a novel data-driven beat-selection algorithm to reduce noise and improve the robustness of the method. We compared the wearable PTT measurements with those from a finger-cuff continuous BP device over the course of several perturbations used to modulate BP. RESULTS Our PTT-based wrist-worn device accurately monitored diastolic blood pressure (DBP) and mean arterial pressure (MAP) in a diverse population (N=44 participants) with a mean absolute difference of 2.90 mm Hg and 3.39 mm Hg for DBP and MAP, respectively, after calibration. Meanwhile, the mean absolute difference of our systolic BP estimation was 5.36 mm Hg, a grade B classification based on the Institute for Electronics and Electrical Engineers standard. We have further demonstrated the ability of our device to capture the commonly observed demographic differences in underlying arterial stiffness. CONCLUSIONS Accurate DBP and MAP estimation, along with grade B systolic BP estimation, using a convenient wearable device can empower users and facilitate remote BP monitoring in medically underserved areas, thus providing widespread hypertension screening and management for health equity.
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Affiliation(s)
- Venu Ganti
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, United States
| | - Andrew M Carek
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, United States
| | - Hewon Jung
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, United States
| | - Adith V Srivatsa
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, United States
| | | | | | - Omer T Inan
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, United States
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, United States
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7
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Tseng SH, Liang BJ, Wang W, Tsai BX, Hu PS. Monitoring adaptation of skin tissue oxygenation during cycling ergometer exercise by frequency-domain diffuse optical spectroscopy. BIOMEDICAL OPTICS EXPRESS 2021; 12:5023-5035. [PMID: 34513240 PMCID: PMC8407841 DOI: 10.1364/boe.428207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 07/04/2021] [Accepted: 07/09/2021] [Indexed: 06/13/2023]
Abstract
In addition to supplying oxygen molecule O2 for metabolic functions during the adaptation to exercise, blood also plays a critical role in heat dissipation for core temperature stabilization. This study investigates the status of hemodynamic oxygenation in the forearm's skin tissue of three participants during a complete ergometer exercise from the resting to exercising, and to recovering conditions using a three-wavelength frequency-domain diffuse reflectance spectroscopy (FD DRS) alongside the monitoring of heartbeat rate and skin temperature. The FD DRS system was synchronized with radiofrequency (RF)-modulated input photon sources and the respective output to extract time-course absorption and scattering coefficients of the skin tissue, which, through the fitting of lambert's law of absorbance, can be used to determine the concentration of oxygenated/deoxygenated hemoglobin molecules, and consequentially, the oxygen saturation of skin tissue and total hemoglobin (THb) concentration. Expressly, a sudden jump in heartbeat rate at the beginning of the exercise, a temporal lag of the rising edge of skin temperature behind that of the THb concentration in the procession of step-wise incremental working intensity, and the uprising of THb in the exhaustion zone in responses to the physiological adaptation to exercise were identified. Finally, conclusive remarks were drawn that the FD DRS system is useful in extracting the hemodynamic properties of forearm skin which is often being neglected in previous exercise physiology studies by DRS-related techniques. The detailed variation of hemodynamic and optical scattering parameters of forearm skin elucidated in the studies can be applied for the analysis of athletes' physiological status, and may be a potential reference for the design of future wearable devices.
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Affiliation(s)
- Sheng-Hao Tseng
- Department of Photonics, National Cheng Kung University, Tainan, 701, Taiwan
| | - Bo-Jian Liang
- Department of Photonics, National Cheng Kung University, Tainan, 701, Taiwan
| | - Wen Wang
- Department of Photonics, National Cheng Kung University, Tainan, 701, Taiwan
| | - Bo-Xiang Tsai
- College of Photonics, National Yang Ming Chiao Tung University, Tainan, 71150, Taiwan
| | - Po-Sheng Hu
- College of Photonics, National Yang Ming Chiao Tung University, Tainan, 71150, Taiwan
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8
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Han T, Yang M, Yang F, Zhao L, Jiang Y, Li C. A three-dimensional modeling method for quantitative photoacoustic breast imaging with handheld probe. PHOTOACOUSTICS 2021; 21:100222. [PMID: 33318929 PMCID: PMC7726342 DOI: 10.1016/j.pacs.2020.100222] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/10/2020] [Accepted: 11/12/2020] [Indexed: 05/08/2023]
Abstract
By providing complementary functional information, photoacoustic (PA) breast imaging based on the handheld ultrasound (US) probe has demonstrated promising potential for breast cancer diagnosis. However, the quantitative PA imaging primarily relies on the knowledge of the optical fluence distribution in the three-dimensional (3D) heterogeneous breast tissue. Previous studies based on the handheld system generally provided two-dimensional (2D) B-scan results, which contains limited anatomical information of the tissue and the lesion. This study proposed a method to perform 3D modeling of the photon transportation for dual-modality PA/US system based on the local 3D breast anatomical information by scanning US probe. Then the calculated optical fluence distribution can be used for PA imaging. Our phantom and clinical pilot study results demonstrated that this method has potential to improve the accuracy of the quantitative PA breast imaging, and it can also be used in other clinical implementations.
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Affiliation(s)
- Tao Han
- Biomedical Engineering Department, Peking University, Beijing, 100871, China
| | - Meng Yang
- Department of Ultrasonography, Peking Union Medical College Hospital, Beijing, 100730, China
| | - Fang Yang
- Mindray Bio-Medical Electronics Co., Ltd., Shenzhen, 518057, China
| | - Lingyi Zhao
- Biomedical Engineering Department, Peking University, Beijing, 100871, China
| | - Yuxin Jiang
- Department of Ultrasonography, Peking Union Medical College Hospital, Beijing, 100730, China
| | - Changhui Li
- Biomedical Engineering Department, Peking University, Beijing, 100871, China
- Corresponding author.
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9
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Phan T, Rowland R, Ponticorvo A, Le BC, Wilson RH, Sharif SA, Kennedy GT, Bernal N, Durkin AJ. Characterizing reduced scattering coefficient of normal human skin across different anatomic locations and Fitzpatrick skin types using spatial frequency domain imaging. JOURNAL OF BIOMEDICAL OPTICS 2021; 26:JBO-200290R. [PMID: 33569936 PMCID: PMC7874851 DOI: 10.1117/1.jbo.26.2.026001] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 12/23/2020] [Indexed: 05/20/2023]
Abstract
SIGNIFICANCE Spatial frequency domain imaging (SFDI), a noncontact wide-field imaging technique using patterned illumination with multiple wavelengths, has been used to quantitatively measure structural and functional parameters of in vivo tissue. Using SFDI in a porcine model, we previously found that scattering changes in skin could potentially be used to noninvasively assess burn severity and monitor wound healing. Translating these findings to human subjects necessitates a better understanding of the variation in "baseline" human skin scattering properties across skin types and anatomical locations. AIM Using SFDI, we aim to characterize the variation in the reduced scattering coefficient (μs') for skin across a range of pigmentation and anatomic sites (including common burn locations) for normal human subjects. These measurements are expected to characterize baseline human skin properties to inform our use of SFDI for clinical burn severity and wound healing assessments. APPROACH SFDI was used to measure μs' in the visible- and near-infrared regime (471 to 851 nm) in 15 subjects at 10 anatomical locations. Subjects varied in age, gender, and Fitzpatrick skin type. RESULTS For all anatomical locations, the coefficient of variation in measured μs' decreased with increasing wavelength. High intersubject variation in μs' at visible wavelengths coincided with large values of the melanin extinction coefficient at those wavelengths. At 851 nm, where intersubject variation in μs' was smallest for all anatomical locations and absorption from melanin is minimal, significant intrasubject differences in μs' were observed at the different anatomical locations. CONCLUSIONS Our study is the first report of wide-field mapping of human skin scattering properties across multiple skin types and anatomical locations using SFDI. Measured μs' values varied notably between skin types at wavelengths where absorption from melanin was prominent. Additionally, μs' varied considerably across different anatomical locations at 851 nm, where the confounding effects from melanin absorption are minimized.
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Affiliation(s)
- Thinh Phan
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, Irvine, California, United States
- University of California, Irvine, Department of Biomedical Engineering, Irvine, California, United States
| | - Rebecca Rowland
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, Irvine, California, United States
| | - Adrien Ponticorvo
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, Irvine, California, United States
| | - Binh C. Le
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, Irvine, California, United States
| | - Robert H. Wilson
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, Irvine, California, United States
| | - Seyed A. Sharif
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, Irvine, California, United States
| | - Gordon T. Kennedy
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, Irvine, California, United States
| | - Nicole Bernal
- University of California, Irvine, UC Irvine Regional Burn Center, Department of Surgery, Orange, California, United States
| | - Anthony J. Durkin
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, Irvine, California, United States
- University of California, Irvine, Department of Biomedical Engineering, Irvine, California, United States
- Address all correspondence to Anthony J. Durkin,
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10
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Ulrich L, Held KG, Jaeger M, Frenz M, Akarçay HG. Reliability assessment for blood oxygen saturation levels measured with optoacoustic imaging. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:1-15. [PMID: 32323509 PMCID: PMC7175414 DOI: 10.1117/1.jbo.25.4.046005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 03/25/2020] [Indexed: 06/11/2023]
Abstract
SIGNIFICANCE Quantitative optoacoustic (OA) imaging has the potential to provide blood oxygen saturation (SO2) estimates due to the proportionality between the measured signal and the blood's absorption coefficient. However, due to the wavelength-dependent attenuation of light in tissue, a spectral correction of the OA signals is required, and a prime challenge is the validation of both the optical characterization of the tissue and the SO2. AIM We propose to assess the reliability of SO2 levels retrieved from spectral fitting by measuring the similarity of OA spectra to the fitted blood absorption spectra. APPROACH We introduce a metric that quantifies the trends of blood spectra by assigning a pair of spectral slopes to each spectrum. The applicability of the metric is illustrated with in vivo measurements on a human forearm. RESULTS We show that physiologically sound SO2 values do not necessarily imply a successful spectral correction and demonstrate how the metric can be used to distinguish SO2 values that are trustworthy from unreliable ones. CONCLUSIONS The metric is independent of the methods used for the OA data acquisition, image reconstruction, and spectral correction, thus it can be readily combined with existing approaches, in order to monitor the accuracy of quantitative OA imaging.
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Affiliation(s)
- Leonie Ulrich
- University of Bern, Institute of Applied Physics, Biomedical Photonics, Bern, Switzerland
| | - Kai Gerrit Held
- University of Bern, Institute of Applied Physics, Biomedical Photonics, Bern, Switzerland
- ABB Switzerland, Corporate Research, Baden-Daettwil, Switzerland
| | - Michael Jaeger
- University of Bern, Institute of Applied Physics, Biomedical Photonics, Bern, Switzerland
| | - Martin Frenz
- University of Bern, Institute of Applied Physics, Biomedical Photonics, Bern, Switzerland
| | - Hidayet Günhan Akarçay
- University of Bern, Institute of Applied Physics, Biomedical Photonics, Bern, Switzerland
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11
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Shimojo Y, Nishimura T, Hazama H, Ozawa T, Awazu K. Measurement of absorption and reduced scattering coefficients in Asian human epidermis, dermis, and subcutaneous fat tissues in the 400- to 1100-nm wavelength range for optical penetration depth and energy deposition analysis. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:1-14. [PMID: 32356424 PMCID: PMC7191311 DOI: 10.1117/1.jbo.25.4.045002] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 04/20/2020] [Indexed: 05/02/2023]
Abstract
SIGNIFICANCE In laser therapy and diagnosis of skin diseases, the irradiated light distribution, which is determined by the absorption coefficient μa and reduced scattering coefficient μs' of the epidermis, dermis, and subcutaneous fat, affects the treatment outcome and diagnosis accuracy. Although values for μa and μs' have been reported, detailed analysis for Asian skin tissues is still lacking. AIM We present μa and μs' measurements of Asian skin tissues in the 400- to 1100-nm wavelength range for evaluating optical penetration depth and energy deposition. APPROACH The measurements with Asian human skin samples are performed employing a double integrating sphere spectrometric system and an inverse Monte Carlo technique. Using the measured parameters, the optical penetration depth and energy deposition are quantitatively analyzed. RESULTS The μa of the epidermis layer varies among different ethnic groups, while the μa of the other layers and the μs' of all of the layers exhibit almost no differences. The analysis reveals that the optical penetration depth and the energy deposition affect the photodynamic therapy treatment depth and the heat production in skin tissue, respectively. CONCLUSIONS The experimentally measured values of μa and μs' for Asian skin tissues are presented, and the light behavior in Asian skin tissues is analyzed using a layered tissue model.
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Affiliation(s)
- Yu Shimojo
- Osaka University, Graduate School of Engineering, Suita, Japan
- Address all correspondence to Yu Shimojo, E-mail: ; Takahiro Nishimura, E-mail:
| | - Takahiro Nishimura
- Osaka University, Graduate School of Engineering, Suita, Japan
- Address all correspondence to Yu Shimojo, E-mail: ; Takahiro Nishimura, E-mail:
| | - Hisanao Hazama
- Osaka University, Graduate School of Engineering, Suita, Japan
| | - Toshiyuki Ozawa
- Osaka City University, Graduate School of Medicine, Department of Dermatology, Osaka, Japan
| | - Kunio Awazu
- Osaka University, Graduate School of Engineering, Suita, Japan
- Osaka University, Graduate School of Frontier Biosciences, Suita, Japan
- Osaka University, Global Center for Medical Engineering and Informatics, Suita, Japan
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12
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Bent B, Goldstein BA, Kibbe WA, Dunn JP. Investigating sources of inaccuracy in wearable optical heart rate sensors. NPJ Digit Med 2020; 3:18. [PMID: 32047863 PMCID: PMC7010823 DOI: 10.1038/s41746-020-0226-6] [Citation(s) in RCA: 240] [Impact Index Per Article: 60.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 01/17/2020] [Indexed: 11/15/2022] Open
Abstract
As wearable technologies are being increasingly used for clinical research and healthcare, it is critical to understand their accuracy and determine how measurement errors may affect research conclusions and impact healthcare decision-making. Accuracy of wearable technologies has been a hotly debated topic in both the research and popular science literature. Currently, wearable technology companies are responsible for assessing and reporting the accuracy of their products, but little information about the evaluation method is made publicly available. Heart rate measurements from wearables are derived from photoplethysmography (PPG), an optical method for measuring changes in blood volume under the skin. Potential inaccuracies in PPG stem from three major areas, includes (1) diverse skin types, (2) motion artifacts, and (3) signal crossover. To date, no study has systematically explored the accuracy of wearables across the full range of skin tones. Here, we explored heart rate and PPG data from consumer- and research-grade wearables under multiple circumstances to test whether and to what extent these inaccuracies exist. We saw no statistically significant difference in accuracy across skin tones, but we saw significant differences between devices, and between activity types, notably, that absolute error during activity was, on average, 30% higher than during rest. Our conclusions indicate that different wearables are all reasonably accurate at resting and prolonged elevated heart rate, but that differences exist between devices in responding to changes in activity. This has implications for researchers, clinicians, and consumers in drawing study conclusions, combining study results, and making health-related decisions using these devices.
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Affiliation(s)
- Brinnae Bent
- Department of Biomedical Engineering, Duke University, Durham, NC USA
| | | | - Warren A. Kibbe
- Department of Bioinformatics and Biostatistics, Duke University, Durham, NC USA
| | - Jessilyn P. Dunn
- Department of Biomedical Engineering, Duke University, Durham, NC USA
- Department of Bioinformatics and Biostatistics, Duke University, Durham, NC USA
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13
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Sitiwin E, Madigan MC, Gratton E, Cherepanoff S, Conway RM, Whan R, Macmillan A. Shedding light on melanins within in situ human eye melanocytes using 2-photon microscopy profiling techniques. Sci Rep 2019; 9:18585. [PMID: 31819095 PMCID: PMC6901595 DOI: 10.1038/s41598-019-54871-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 11/12/2019] [Indexed: 01/17/2023] Open
Abstract
Choroidal melanocytes (HCMs) are melanin-producing cells in the vascular uvea of the human eye (iris, ciliary body and choroid). These cranial neural crest-derived cells migrate to populate a mesodermal microenvironment, and display cellular functions and extracellular interactions that are biologically distinct to skin melanocytes. HCMs (and melanins) are important in normal human eye physiology with roles including photoprotection, regulation of oxidative damage and immune responses. To extend knowledge of cytoplasmic melanins and melanosomes in label-free HCMs, a non-invasive 'fit-free' approach, combining 2-photon excitation fluorescence lifetimes and emission spectral imaging with phasor plot segmentation was applied. Intracellular melanin-mapped FLIM phasors showed a linear distribution indicating that HCM melanins are a ratio of two fluorophores, eumelanin and pheomelanin. A quantitative histogram of HCM melanins was generated by identifying the image pixel fraction contributed by phasor clusters mapped to varying eumelanin/pheomelanin ratio. Eumelanin-enriched dark HCM regions mapped to phasors with shorter lifetimes and longer spectral emission (580-625 nm) and pheomelanin-enriched lighter pigmented HCM regions mapped to phasors with longer lifetimes and shorter spectral emission (550-585 nm). Overall, we demonstrated that these methods can identify and quantitatively profile the heterogeneous eumelanins/pheomelanins within in situ HCMs, and visualize melanosome spatial distributions, not previously reported for these cells.
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Affiliation(s)
- Ephrem Sitiwin
- School of Optometry and Vision Science, University of New South Wales, Kensington, NSW, 2052, Australia.
- Biomedical Imaging Facility, University of New South Wales, Kensington, NSW, 2052, Australia.
- Save Sight Institute, University of Sydney, NSW, 2000, Sydney, Australia.
| | - Michele C Madigan
- School of Optometry and Vision Science, University of New South Wales, Kensington, NSW, 2052, Australia
- Save Sight Institute, University of Sydney, NSW, 2000, Sydney, Australia
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California Irvine, California, USA
| | | | - Robert Max Conway
- Save Sight Institute, University of Sydney, NSW, 2000, Sydney, Australia
| | - Renee Whan
- Biomedical Imaging Facility, University of New South Wales, Kensington, NSW, 2052, Australia
| | - Alexander Macmillan
- Biomedical Imaging Facility, University of New South Wales, Kensington, NSW, 2052, Australia.
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14
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Zhang Y, Moy AJ, Feng X, Nguyen HTM, Reichenberg JS, Markey MK, Tunnell JW. Physiological model using diffuse reflectance spectroscopy for nonmelanoma skin cancer diagnosis. JOURNAL OF BIOPHOTONICS 2019; 12:e201900154. [PMID: 31325232 DOI: 10.1002/jbio.201900154] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 07/10/2019] [Accepted: 07/17/2019] [Indexed: 05/25/2023]
Abstract
Diffuse reflectance spectroscopy (DRS) is a noninvasive, fast, and low-cost technology with potential to assist cancer diagnosis. The goal of this study was to test the capability of our physiological model, a computational Monte Carlo lookup table inverse model, for nonmelanoma skin cancer diagnosis. We applied this model on a clinical DRS dataset to extract scattering parameters, blood volume fraction, oxygen saturation and vessel radius. We found that the model was able to capture physiological information relevant to skin cancer. We used the extracted parameters to classify (basal cell carcinoma [BCC], squamous cell carcinoma [SCC]) vs actinic keratosis (AK) and (BCC, SCC, AK) vs normal. The area under the receiver operating characteristic curve achieved by the classifiers trained on the parameters extracted using the physiological model is comparable to that of classifiers trained on features extracted via Principal Component Analysis. Our findings suggest that DRS can reveal physiologic characteristics of skin and this physiologic model offers greater flexibility for diagnosing skin cancer than a pure statistical analysis. Physiological parameters extracted from diffuse reflectance spectra data for nonmelanoma skin cancer diagnosis.
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Affiliation(s)
- Yao Zhang
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas
| | - Austin J Moy
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas
| | - Xu Feng
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas
| | - Hieu T M Nguyen
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas
| | | | - Mia K Markey
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - James W Tunnell
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas
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15
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Dremin V, Zherebtsov E, Bykov A, Popov A, Doronin A, Meglinski I. Influence of blood pulsation on diagnostic volume in pulse oximetry and photoplethysmography measurements. APPLIED OPTICS 2019; 58:9398-9405. [PMID: 31873531 DOI: 10.1364/ao.58.009398] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 10/25/2019] [Indexed: 05/27/2023]
Abstract
Recent advances in the development of ultra-compact semiconductor lasers and technology of printed flexible hybrid electronics have opened broad perspectives for the design of new pulse oximetry and photoplethysmography devices. Conceptual design of optical diagnostic devices requires careful selection of various technical parameters, including spectral range; polarization and intensity of incident light; actual size, geometry, and sensitivity of the detector; and mutual position of the source and detector on the surface of skin. In the current study utilizing a unified Monte Carlo computational tool, we explore the variations in diagnostic volume due to arterial blood pulsation for typical transmitted and back-scattered probing configurations in a human finger. The results of computational studies show that the variations in diagnostic volumes due to arterial pulse wave are notably (up to 45%) different in visible and near-infrared spectral ranges in both transmitted and back-scattered probing geometries. While these variations are acceptable for relative measurements in pulse oximetry and/or photoplethysmography, for absolute measurements, an alignment normalization of diagnostic volume is required and can be done by a computational approach utilized in the framework of the current study.
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16
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Johansson JD, Portaluppi D, Buttafava M, Villa F. A multipixel diffuse correlation spectroscopy system based on a single photon avalanche diode array. JOURNAL OF BIOPHOTONICS 2019; 12:e201900091. [PMID: 31339649 DOI: 10.1002/jbio.201900091] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 07/19/2019] [Accepted: 07/21/2019] [Indexed: 05/21/2023]
Abstract
The autocorrelation of laser speckles from coherent near infrared light is used for noninvasive estimates of relative changes in blood perfusion in techniques such as laser Doppler flowmetry (LDF) and diffuse correlation spectroscopy (DCS). In this study, a 2D array of single photon avalanche diodes (SPADs) was used to combine the strengths of multiple detectors in LDF with high light sensitivity in DCS. The system was tested on milk phantoms with varying detector fiber diameter (200 and 600 μm), source-detector fiber separation (4.6-10.2 mm), fiber-SPAD distance (2.5-36.5 mm), contiguous measurement time per repetition for the autocorrelation (1-33 ms) and temperature (15.6-46.7°C). An in vivo blood occlusion test was also performed. The multipixel approach improved signal-to-noise ratio (SNR) and, in our setup, the use of a multimode detector fiber was beneficial for SNR. In conclusion, the multipixel system works, but improvements and further studies regarding, for example, the data acquisition and optimal settings are still needed.
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Affiliation(s)
| | - Davide Portaluppi
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan, Italy
| | - Mauro Buttafava
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan, Italy
| | - Federica Villa
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan, Italy
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17
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Cheng NY, Lin YL, Fang MC, Lu WH, Yang CC, Tseng SH. Noninvasive transcutaneous bilirubin assessment of neonates with hyperbilirubinemia using a photon diffusion theory-based method. BIOMEDICAL OPTICS EXPRESS 2019; 10:2969-2984. [PMID: 31259067 PMCID: PMC6583349 DOI: 10.1364/boe.10.002969] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 05/18/2019] [Accepted: 05/19/2019] [Indexed: 06/09/2023]
Abstract
Transcutaneous bilirubinometers are widely used to screen neonatal jaundice. However, it was reported that their accuracy is compromised at low and high bilirubin levels. We used a photon diffusion theory-based method valid in the 450-600 nm wavelength region to overcome this obstacle. Our clinical study results showed that our system could properly determine the transcutaneous bilirubin concentrations at total serum bilirubin levels higher than 14 mg/dL, where a commercial bilirubinometer failed to provide proper results in several cases. These findings suggested that photon diffusion theory could be employed to improve the core algorithm of modern bilirubinometers and enhance their applicability.
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Affiliation(s)
- Nan-Yu Cheng
- Department of Photonics, National Cheng Kung University, Tainan, Taiwan
| | - Yi-Ling Lin
- Department of Photonics, National Cheng Kung University, Tainan, Taiwan
| | - Ming-Chien Fang
- Department of Photonics, National Cheng Kung University, Tainan, Taiwan
| | - Wen-Hsien Lu
- Department of Pediatrics, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
| | - Chin-Chieh Yang
- Department of Pediatrics, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
| | - Sheng-Hao Tseng
- Department of Photonics, National Cheng Kung University, Tainan, Taiwan
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18
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Horan ST, Gardner AR, Saager R, Durkin AJ, Venugopalan V. Recovery of layered tissue optical properties from spatial frequency-domain spectroscopy and a deterministic radiative transport solver. JOURNAL OF BIOMEDICAL OPTICS 2018; 24:1-11. [PMID: 30456934 PMCID: PMC6995875 DOI: 10.1117/1.jbo.24.7.071607] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 10/12/2018] [Indexed: 05/26/2023]
Abstract
We present a method to recover absorption and reduced scattering spectra for each layer of a two-layer turbid media from spatial frequency-domain spectroscopy data. We focus on systems in which the thickness of the top layer is less than the transport mean free path ( 0.1 - 0.8l * ) . We utilize an analytic forward solver, based upon the N'th-order spherical harmonic expansion with Fourier decomposition ( SHEFN ) method in conjunction with a multistage inverse solver. We test our method with data obtained using spatial frequency-domain spectroscopy with 32 evenly spaced wavelengths within λ = 450 to 1000 nm on six-layered tissue phantoms with distinct optical properties. We demonstrate that this approach can recover absorption and reduced scattering coefficient spectra for both layers with accuracy comparable with current Monte Carlo methods but with lower computational cost and potential flexibility to easily handle variations in parameters such as the scattering phase function or material refractive index. To our knowledge, this approach utilizes the most accurate deterministic forward solver used in such problems and can successfully recover properties from a two-layer media with superficial layer thicknesses.
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Affiliation(s)
- Sean T. Horan
- University of California, Department of Mathematics, Irvine, California, United States
- University of California, Beckman Laser Institute, Laser Microbeam and Medical Program, Irvine, California, United States
| | - Adam R. Gardner
- University of California, Beckman Laser Institute, Laser Microbeam and Medical Program, Irvine, California, United States
- University of California, Department of Chemical Engineering and Materials Science, Irvine, California, United States
| | - Rolf Saager
- University of California, Beckman Laser Institute, Laser Microbeam and Medical Program, Irvine, California, United States
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
| | - Anthony J. Durkin
- University of California, Beckman Laser Institute, Laser Microbeam and Medical Program, Irvine, California, United States
- University of California, Department of Biomedical Engineering, Irvine, California, United States
| | - Vasan Venugopalan
- University of California, Beckman Laser Institute, Laser Microbeam and Medical Program, Irvine, California, United States
- University of California, Department of Chemical Engineering and Materials Science, Irvine, California, United States
- University of California, Department of Biomedical Engineering, Irvine, California, United States
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19
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Jonasson H, Fredriksson I, Bergstrand S, Östgren CJ, Larsson M, Strömberg T. In vivo characterization of light scattering properties of human skin in the 475- to 850-nm wavelength range in a Swedish cohort. JOURNAL OF BIOMEDICAL OPTICS 2018; 23:1-6. [PMID: 30267487 DOI: 10.1117/1.jbo.23.12.121608] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 08/31/2018] [Indexed: 05/04/2023]
Abstract
We have determined in vivo optical scattering properties of normal human skin in 1734 subjects, mostly with fair skin type, within the Swedish CArdioPulmonary bioImage Study. The measurements were performed with a noninvasive system, integrating spatially resolved diffuse reflectance spectroscopy and laser Doppler flowmetry. Data were analyzed with an inverse Monte Carlo algorithm, accounting for both scattering, geometrical, and absorbing properties of the tissue. The reduced scattering coefficient was found to decrease from 3.16 ± 0.72 to 1.13 ± 0.27 mm-1 (mean ± SD) in the 475- to 850-nm wavelength range. There was a negative correlation between the reduced scattering coefficient and age, and a significant difference between men and women in the reduced scattering coefficient as well as in the fraction of small scattering particles. This large study on tissue scattering with mean values and normal variation can serve as a reference when designing diagnostic techniques or when evaluating the effect of therapeutic optical systems.
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Affiliation(s)
- Hanna Jonasson
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
- Linköping University, Department of Medical and Health Sciences, Linköping, Sweden
| | - Ingemar Fredriksson
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
- Perimed AB, Järfälla, Stockholm, Sweden
| | - Sara Bergstrand
- Linköping University, Department of Medical and Health Sciences, Linköping, Sweden
| | - Carl Johan Östgren
- Linköping University, Department of Medical and Health Sciences, Linköping, Sweden
| | - Marcus Larsson
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
| | - Tomas Strömberg
- Linköping University, Department of Biomedical Engineering, Linköping, Sweden
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20
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Myllylä T, Harju M, Korhonen V, Bykov A, Kiviniemi V, Meglinski I. Assessment of the dynamics of human glymphatic system by near-infrared spectroscopy. JOURNAL OF BIOPHOTONICS 2018; 11:e201700123. [PMID: 28802090 DOI: 10.1002/jbio.201700123] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Revised: 07/25/2017] [Accepted: 08/10/2017] [Indexed: 06/07/2023]
Abstract
Fluctuations in brain water content has attracted increasing interest, particularly as regards studies of the glymphatic system, which is connected with the complex organization of dural lymphatic vessels, responsible for cleaning tissue. Disturbances of glymphatic circulation are associated with several brain disorders, including dementia. This article introduces an approach to noninvasive measurement of water dynamics in the human brain utilizing near-infrared spectroscopy (NIRS). We demonstrate the possibility to sense dynamic variations of water content between the skull and grey matter, for instance, in the subarachnoid space. Measured fluctuations in water content, especially in the cerebrospinal fluid (CSF), are assumed to be correlated with the dynamics of glymphatic circulation. The sampling volume for the NIRS optode was estimated by Monte Carlo modelling for the wavelengths of 660, 740, 830 and 980 nm. In addition, using combinations of these wavelengths, this article presents the calculation models for quantifying water and haemodynamics. The presented NIRS technique allows long-term functional brain monitoring, including sleeping time. Furthermore, it is used in combination with different magnetic neuroimaging techniques, particularly magnetic resonance encephalography. Using the combined setup, we report the preliminary results on the interaction between CSF and blood oxygen level-dependent fluctuations.
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Affiliation(s)
- Teemu Myllylä
- Optoelectronics and Measurement Techniques Unit, University of Oulu, Oulu, Finland
- Oulu Functional Neuroimaging Group, Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland
| | - Markus Harju
- Inverse Problems Group, Department of Mathematical Sciences, University of Oulu, Oulu, Finland
| | - Vesa Korhonen
- Oulu Functional Neuroimaging Group, Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland
- Department of Diagnostic Radiology, Medical Research Center (MRC), Oulu University Hospital, Oulu, Finland
| | - Alexander Bykov
- Optoelectronics and Measurement Techniques Unit, University of Oulu, Oulu, Finland
- Department of Photonics and Optical Information Technology, ITMO University, St Petersburg, Russia
| | - Vesa Kiviniemi
- Oulu Functional Neuroimaging Group, Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland
- Department of Diagnostic Radiology, Medical Research Center (MRC), Oulu University Hospital, Oulu, Finland
| | - Igor Meglinski
- Optoelectronics and Measurement Techniques Unit, University of Oulu, Oulu, Finland
- Department of Photonics and Optical Information Technology, ITMO University, St Petersburg, Russia
- Institute of Biology, Irkutsk State University, Irkutsk, Russia
- Institute of Engineering Physics for Biomedicine, National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow, Russia
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21
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Evans CL. Nonlinear Optical Microscopy for Melanoma: Challenges, Tools and Opportunities. Photochem Photobiol 2018; 94:624-632. [PMID: 29485199 DOI: 10.1111/php.12916] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 02/17/2018] [Indexed: 02/02/2023]
Abstract
The natural pigments known as melanins are thought to play a role in the etiology and progression of melanoma, but many of their roles are currently not well understood. While quantification of melanins have, up until now, have been performed in bulk tissue ex vivo, new imaging technologies have unlocked the means to visualize and quantify melanins at the sub-cellular scale. The nonlinear imaging methods known as pump-probe, coherent Raman, and sum-frequency absorption microscopies provide subcellular resolution imaging of melanins, enabling label-free, longitudinal quantification of both eumelanin and pheomelanin in situ and in vivo. These nonlinear imaging toolkits have been well proven in both animal models and human samples, moving them tantalizingly close to clinical application. Future efforts integrating these tools into practical, mobile imaging systems will provide immense benefit both to clinical research and practice.
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Affiliation(s)
- Conor L Evans
- Wellman Center for Photomedicine, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA
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22
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Spigulis J, Oshina I, Berzina A, Bykov A. Smartphone snapshot mapping of skin chromophores under triple-wavelength laser illumination. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:91508. [PMID: 28253387 DOI: 10.1117/1.jbo.22.9.091508] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 02/10/2017] [Indexed: 05/12/2023]
Abstract
Chromophore distribution maps are useful tools for skin malformation severity assessment and for monitoring of skin recovery after burns, surgeries, and other interactions. The chromophore maps can be obtained by processing several spectral images of skin, e.g., captured by hyperspectral or multispectral cameras during seconds or even minutes. To avoid motion artifacts and simplify the procedure, a single-snapshot technique for mapping melanin, oxyhemoglobin, and deoxyhemoglobin of in-vivo skin by a smartphone under simultaneous three-wavelength (448–532–659 nm) laser illumination is proposed and examined. Three monochromatic spectral images related to the illumination wavelengths were extracted from the smartphone camera RGB image data set with respect to crosstalk between the RGB detection bands. Spectral images were further processed accordingly to Beer’s law in a three chromophore approximation. Photon absorption path lengths in skin at the exploited wavelengths were estimated by means of Monte Carlo simulations. The technique was validated clinically on three kinds of skin lesions: nevi, hemangiomas, and seborrheic keratosis. Design of the developed add-on laser illumination system, image-processing details, and the results of clinical measurements are presented and discussed.
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Affiliation(s)
- Janis Spigulis
- University of Latvia, Biophotonics Laboratory, Institute of Atomic Physics and Spectroscopy, Riga, Latvia
| | - Ilze Oshina
- University of Latvia, Biophotonics Laboratory, Institute of Atomic Physics and Spectroscopy, Riga, Latvia
| | - Anna Berzina
- University of Latvia, Biophotonics Laboratory, Institute of Atomic Physics and Spectroscopy, Riga, Latvia
| | - Alexander Bykov
- University of Oulu, Optoelectronics and Measurement Techniques Unit, Faculty of Information Technology and Electrical Engineering, Oulu, Finland
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23
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Nwafor CI, Plant KD, King DR, McCall BP, Squiers JJ, Fan W, DiMaio JM, Thatcher JE. Assessment of a noninvasive optical photoplethysmography imaging device with dynamic tissue phantom models. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:1-9. [PMID: 28895317 DOI: 10.1117/1.jbo.22.9.096003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 08/09/2017] [Indexed: 06/07/2023]
Abstract
Noncontact photoplethysmography (PPG) has been studied as a method to provide low-cost, noninvasive, two-dimensional blood oxygenation measurements and medical imaging for a variety of near-surface pathologies. To evaluate this technology in a laboratory setting, dynamic tissue phantoms were developed with tunable parameters that mimic physiologic properties of the skin, including blood vessel volume change, pulse wave frequency, and tissue scattering and absorption. Tissue phantoms were generated using an elastic tubing to represent a blood vessel where the luminal volume could be modulated with a pulsatile fluid flow. The blood was mimicked with a scattering and absorbing motility standard, and the tissue with a gelatin-lipid emulsion hydrogel. A noncontact PPG imaging system was then evaluated using the phantoms. Noncontact PPG imaging accurately identified pulse frequency, and PPG signals from these phantoms suggest that the phantoms can be used to evaluate noncontact PPG imaging systems. Such information may be valuable to the development of future PPG imaging systems.
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Affiliation(s)
| | | | | | | | - John J Squiers
- Spectral MD, Inc., Texas, United States
- Baylor University Medical Center, Department of Surgery, Texas, United States
- Baylor Research Institute, Baylor Scott and White Health, Texas, United States
| | | | - J Michael DiMaio
- Spectral MD, Inc., Texas, United States
- Baylor Research Institute, Baylor Scott and White Health, Texas, United States
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24
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Piazena H, Meffert H, Uebelhack R. Spectral Remittance and Transmittance of Visible and Infrared-A Radiation in Human Skin-Comparison Betweenin vivoMeasurements and Model Calculations. Photochem Photobiol 2017; 93:1449-1461. [DOI: 10.1111/php.12785] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 04/04/2017] [Indexed: 11/26/2022]
Affiliation(s)
- Helmut Piazena
- Medical Photobiology Group; Charité - University Medicine Berlin; Berlin Germany
| | | | - Ralf Uebelhack
- Medical Photobiology Group; Charité - University Medicine Berlin; Berlin Germany
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25
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Baruch D, Abookasis D. Multimodal optical setup based on spectrometer and cameras combination for biological tissue characterization with spatially modulated illumination. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:46007. [PMID: 28425559 DOI: 10.1117/1.jbo.22.4.046007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 03/29/2017] [Indexed: 06/07/2023]
Abstract
The application of optical techniques as tools for biomedical research has generated substantial interest for the ability of such methodologies to simultaneously measure biochemical and morphological parameters of tissue. Ongoing optimization of optical techniques may introduce such tools as alternative or complementary to conventional methodologies. The common approach shared by current optical techniques lies in the independent acquisition of tissue’s optical properties (i.e., absorption and reduced scattering coefficients) from reflected or transmitted light. Such optical parameters, in turn, provide detailed information regarding both the concentrations of clinically relevant chromophores and macroscopic structural variations in tissue. We couple a noncontact optical setup with a simple analysis algorithm to obtain absorption and scattering coefficients of biological samples under test. Technically, a portable picoprojector projects serial sinusoidal patterns at low and high spatial frequencies, while a spectrometer and two independent CCD cameras simultaneously acquire the reflected diffuse light through a single spectrometer and two separate CCD cameras having different bandpass filters at nonisosbestic and isosbestic wavelengths in front of each. This configuration fills the gaps in each other’s capabilities for acquiring optical properties of tissue at high spectral and spatial resolution. Experiments were performed on both tissue-mimicking phantoms as well as hands of healthy human volunteers to quantify their optical properties as proof of concept for the present technique. In a separate experiment, we derived the optical properties of the hand skin from the measured diffuse reflectance, based on a recently developed camera model. Additionally, oxygen saturation levels of tissue measured by the system were found to agree well with reference values. Taken together, the present results demonstrate the potential of this integrated setup for diagnostic and research applications.
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Affiliation(s)
- Daniel Baruch
- Ariel University, Department of Electrical and Electronics Engineering, Ariel, IsraelbAriel University, Department of Physics, Ariel, Israel
| | - David Abookasis
- Ariel University, Department of Electrical and Electronics Engineering, Ariel, Israel
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Energy Harvesting by Subcutaneous Solar Cells: A Long-Term Study on Achievable Energy Output. Ann Biomed Eng 2017; 45:1172-1180. [PMID: 28050727 PMCID: PMC5397472 DOI: 10.1007/s10439-016-1774-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 12/03/2016] [Indexed: 11/28/2022]
Abstract
Active electronic implants are powered by primary batteries, which induces the necessity of implant replacement after battery depletion. This causes repeated interventions in a patients’ life, which bears the risk of complications and is costly. By using energy harvesting devices to power the implant, device replacements may be avoided and the device size may be reduced dramatically. Recently, several groups presented prototypes of implants powered by subcutaneous solar cells. However, data about the expected real-life power output of subcutaneously implanted solar cells was lacking so far. In this study, we report the first real-life validation data of energy harvesting by subcutaneous solar cells. Portable light measurement devices that feature solar cells (cell area = 3.6 cm2) and continuously measure a subcutaneous solar cell’s output power were built. The measurement devices were worn by volunteers in their daily routine in summer, autumn and winter. In addition to the measured output power, influences such as season, weather and human activity were analyzed. The obtained mean power over the whole study period was 67 µW (=19 µW cm−2), which is sufficient to power e.g. a cardiac pacemaker.
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Göröcs Z, Rivenson Y, Ceylan Koydemir H, Tseng D, Troy TL, Demas V, Ozcan A. Quantitative Fluorescence Sensing Through Highly Autofluorescent, Scattering, and Absorbing Media Using Mobile Microscopy. ACS NANO 2016; 10:8989-99. [PMID: 27622866 DOI: 10.1021/acsnano.6b05129] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Compact and cost-effective systems for in vivo fluorescence and near-infrared imaging in combination with activatable reporters embedded inside the skin to sample interstitial fluid or blood can enable a variety of biomedical applications. However, the strong autofluorescence of human skin creates an obstacle for fluorescence-based sensing. Here we introduce a method for quantitative fluorescence sensing through highly autofluorescent, scattering, and absorbing media. For this, we created a compact and cost-effective fluorescence microscope weighing <40 g and used it to measure various concentrations of a fluorescent dye embedded inside a tissue phantom, which was designed to mimic the optical characteristics of human skin. We used an elliptical Gaussian beam excitation to digitally separate tissue autofluorescence from target fluorescence, although they severely overlap in both space and optical spectrum. Using ∼10-fold less excitation intensity than the safety limit for skin radiation exposure, we successfully quantified the density of the embedded fluorophores by imaging the skin phantom surface and achieved a detection limit of ∼5 × 10(5) and ∼2.5 × 10(7) fluorophores within ∼0.01 μL sample volume that is positioned 0.5 and 2 mm below the phantom surface, corresponding to a concentration of 105.9 pg/mL and 5.3 ng/mL, respectively. We also confirmed that this approach can track the spatial misalignments of the mobile microscope with respect to the embedded target fluorescent volume. This wearable microscopy platform might be useful for designing implantable biochemical sensors with the capability of spatial multiplexing to continuously monitor a panel of biomarkers and chronic conditions even at patients' home.
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Affiliation(s)
| | | | | | | | - Tamara L Troy
- Verily Life Sciences, LLC , Mountain View, California 94043, United States
| | - Vasiliki Demas
- Verily Life Sciences, LLC , Mountain View, California 94043, United States
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Chen C, Ahmed M, Häfner T, Klämpfl F, Stelzle F, Schmidt M. Fabrication of a turbid optofluidic phantom device with tunable μa and μ's to simulate cutaneous vascular perfusion. Sci Rep 2016; 6:30567. [PMID: 27457535 PMCID: PMC4960568 DOI: 10.1038/srep30567] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 06/27/2016] [Indexed: 11/15/2022] Open
Abstract
Microfluidic devices are oftenly used to calibrate the imaging reconstruction, because they simulate the morphology of microvasculature. However, for lack of optical properties in microfluidics, the functional recovery of oximetry information cannot be verified. In this work, we describe the fabrication of a novel turbid optofluidic tissue phantom. It is designed to mimic the vascular perfusion and the turbid nature of cutaneous tissue. This phantom contains an interior hollow microfluidic structure with a diameter of ϕave = 50 μm. The microfluidic structure includes the geometry of an inlet, a river-like assay and an outlet. This structure can be perfused by hemoglobin solution to mimic the cutaneous micro-circulation. The multiple-layered phantom matrices exhibit the representative optical parameters of human skin cutis, namely the absorption coefficient μa and the reduced scattering coefficient . The geometry of the generated microfluidic structure is investigated by using Spectral-Domain Optical Coherence Tomography. This optofluidic phantom bridges the gap between tissue equivalent phantoms and Lab-On-Chip devices. Perspectively, this device can be used to calibrate a variety of optical angiographic imaging approaches.
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Affiliation(s)
- Chen Chen
- Chair of Photonic Technologies, Friedrich-Alexander Universität Erlangen-Nürnberg, Konrad-Zuse-Str. 3/5, D-91052 Erlangen, Germany
- Erlangen Graduate School in Advanced Optical Technologies, Paul-Gordan-Str. 6, D-91052 Erlangen, Germany
| | - Midhat Ahmed
- Chair of Photonic Technologies, Friedrich-Alexander Universität Erlangen-Nürnberg, Konrad-Zuse-Str. 3/5, D-91052 Erlangen, Germany
- Erlangen Graduate School in Advanced Optical Technologies, Paul-Gordan-Str. 6, D-91052 Erlangen, Germany
| | - Tom Häfner
- Chair of Photonic Technologies, Friedrich-Alexander Universität Erlangen-Nürnberg, Konrad-Zuse-Str. 3/5, D-91052 Erlangen, Germany
- Erlangen Graduate School in Advanced Optical Technologies, Paul-Gordan-Str. 6, D-91052 Erlangen, Germany
| | - Florian Klämpfl
- Chair of Photonic Technologies, Friedrich-Alexander Universität Erlangen-Nürnberg, Konrad-Zuse-Str. 3/5, D-91052 Erlangen, Germany
| | - Florian Stelzle
- Erlangen Graduate School in Advanced Optical Technologies, Paul-Gordan-Str. 6, D-91052 Erlangen, Germany
- Department of Oral and Maxillofacial Surgery, Friedrich-Alexander Universität Erlangen-Nürnberg, Glückstr. 11, D-91054 Erlangen, Germany
| | - Michael Schmidt
- Chair of Photonic Technologies, Friedrich-Alexander Universität Erlangen-Nürnberg, Konrad-Zuse-Str. 3/5, D-91052 Erlangen, Germany
- Erlangen Graduate School in Advanced Optical Technologies, Paul-Gordan-Str. 6, D-91052 Erlangen, Germany
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Park J, Ha M, Yu S, Jung B. Fabrication of various optical tissue phantoms by the spin-coating method. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:65008. [PMID: 27367252 DOI: 10.1117/1.jbo.21.6.065008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Accepted: 06/13/2016] [Indexed: 06/06/2023]
Abstract
Although numerous studies have been performed to fabricate various optical tissue phantom (OTP) models, the fabrication of OTPs that simulate skin layers is laborious and time-consuming owing to the intricate characteristics of skin tissue. This study presents various OTP models that optically and structurally simulate the epidermis–dermis skin layer. The spin-coating method was employed to reproduce a uniform thin layer that mimics the epidermis layer, and the fabrication parameters were optimized for epoxy and silicone reference materials. Various OTP models simulating blood vessels and hyperpigmentation lesions were fabricated using the two reference materials to determine their feasibility. The suitability of each of the two reference materials for OTP fabrication was qualitatively evaluated by comparing the quality of the OTP models.
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Saager RB, Quach A, Rowland RA, Baldado ML, Durkin AJ. Low-cost tissue simulating phantoms with adjustable wavelength-dependent scattering properties in the visible and infrared ranges. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:67001. [PMID: 27292135 PMCID: PMC4904063 DOI: 10.1117/1.jbo.21.6.067001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 05/23/2016] [Indexed: 05/09/2023]
Abstract
We present a method for low-cost fabrication of polydimethylsiloxane (PDMS) tissue simulating phantoms with tunable scattering spectra, spanning visible, and near-infrared regimes. These phantoms use optical polishing agents (aluminum oxide powders) at various grit sizes to approximate in vivo tissue scattering particles across multiple size distributions (range: 17 to 3 μm). This class of tunable scattering phantoms is used to mimic distinct changes in wavelength-dependent scattering properties observed in tissue pathologies such as partial thickness burns. Described by a power-law dependence on wavelength, the scattering magnitude of these phantoms scale linearly with particle concentration over a physiologic range [μs′=(0.5 to 2.0 mm−1)] whereas the scattering spectra, specific to each particle size distribution, correlate to distinct exponential coefficients (range: 0.007 to 0.32). Aluminum oxide powders used in this investigation did not detectably contribute to the absorption properties of these phantoms. The optical properties of these phantoms are verified through inverse adding-doubling methods and the tolerances of this fabrication method are discussed.
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Affiliation(s)
- Rolf B. Saager
- University of California, Irvine, 1002 Health Sciences Road, Irvine, California 92612, United States
- Address all correspondence to: Rolf B. Saager, E-mail:
| | - Alan Quach
- University of California, Irvine, 1002 Health Sciences Road, Irvine, California 92612, United States
| | - Rebecca A. Rowland
- University of California, Irvine, 1002 Health Sciences Road, Irvine, California 92612, United States
| | - Melissa L. Baldado
- University of California, Irvine, 1002 Health Sciences Road, Irvine, California 92612, United States
| | - Anthony J. Durkin
- University of California, Irvine, 1002 Health Sciences Road, Irvine, California 92612, United States
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Saager RB, Sharif A, Kelly KM, Durkin AJ. In vivo isolation of the effects of melanin from underlying hemodynamics across skin types using spatial frequency domain spectroscopy. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:57001. [PMID: 27143641 PMCID: PMC4890358 DOI: 10.1117/1.jbo.21.5.057001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 04/13/2016] [Indexed: 05/03/2023]
Abstract
Skin is a highly structured tissue, raising concerns as to whether skin pigmentation due to epidermal melanin may confound accurate measurements of underlying hemodynamics. Using both venous and arterial cuff occlusions as a means of inducing differential hemodynamic perturbations, we present analyses of spectra limited to the visible or near-infrared regime, in addition to a layered model approach. The influence of melanin, spanning Fitzpatrick skin types I to V, on underlying estimations of hemodynamics in skin as interpreted by these spectral regions are assessed. The layered model provides minimal cross-talk between melanin and hemodynamics and enables removal of problematic correlations between measured tissue oxygenation estimates and skin phototype.
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Affiliation(s)
- Rolf B. Saager
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, 1002 Health Sciences Road East, Irvine, California 92612, United States
- Address all correspondence to: Rolf B. Saager, E-mail:
| | - Ata Sharif
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, 1002 Health Sciences Road East, Irvine, California 92612, United States
| | - Kristen M. Kelly
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, 1002 Health Sciences Road East, Irvine, California 92612, United States
- University of California, Irvine, Department of Dermatology, 118 Medical Surge 1, Irvine, California 92697, United States
| | - Anthony J. Durkin
- University of California, Irvine, Beckman Laser Institute and Medical Clinic, 1002 Health Sciences Road East, Irvine, California 92612, United States
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Chen YW, Chen CC, Huang PJ, Tseng SH. Artificial neural networks for retrieving absorption and reduced scattering spectra from frequency-domain diffuse reflectance spectroscopy at short source-detector separation. BIOMEDICAL OPTICS EXPRESS 2016; 7:1496-510. [PMID: 27446671 PMCID: PMC4929657 DOI: 10.1364/boe.7.001496] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/19/2016] [Accepted: 03/20/2016] [Indexed: 05/26/2023]
Abstract
Diffuse reflectance spectroscopy (DRS) based on the frequency-domain (FD) technique has been employed to investigate the optical properties of deep tissues such as breast and brain using source to detector separation up to 40 mm. Due to the modeling and system limitations, efficient and precise determination of turbid sample optical properties from the FD diffuse reflectance acquired at a source-detector separation (SDS) of around 1 mm has not been demonstrated. In this study, we revealed that at SDS of 1 mm, acquiring FD diffuse reflectance at multiple frequencies is necessary for alleviating the influence of inevitable measurement uncertainty on the optical property recovery accuracy. Furthermore, we developed artificial neural networks (ANNs) trained by Monte Carlo simulation generated databases that were capable of efficiently determining FD reflectance at multiple frequencies. The ANNs could work in conjunction with a least-square optimization algorithm to rapidly (within 1 second), accurately (within 10%) quantify the sample optical properties from FD reflectance measured at SDS of 1 mm. In addition, we demonstrated that incorporating the steady-state apparatus into the FD DRS system with 1 mm SDS would enable obtaining broadband absorption and reduced scattering spectra of turbid samples in the wavelength range from 650 to 1000 nm.
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Affiliation(s)
- Yu-Wen Chen
- Department of Photonics, National Cheng-Kung University, Tainan, 701, Taiwan
- These authors contributed equally to this work and should be considered co-first authors
| | - Chien-Chih Chen
- Department of Photonics, National Cheng-Kung University, Tainan, 701, Taiwan
- These authors contributed equally to this work and should be considered co-first authors
| | - Po-Jung Huang
- Department of Photonics, National Cheng-Kung University, Tainan, 701, Taiwan
| | - Sheng-Hao Tseng
- Department of Photonics, National Cheng-Kung University, Tainan, 701, Taiwan
- Advanced Optoelectronic Technology Center, National Cheng-Kung University, Tainan, 701, Taiwan
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Kim H, Hau NT, Chae YG, Lee BI, Kang HW. 3D printing-assisted fabrication of double-layered optical tissue phantoms for laser tattoo treatments. Lasers Surg Med 2016; 48:392-9. [PMID: 26749358 DOI: 10.1002/lsm.22469] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/23/2015] [Indexed: 11/08/2022]
Abstract
BACKGROUND AND OBJECTIVE Artificial skin phantoms have been developed as an alternative tissue for human skin experiments due to convenient use and easy storage. However, fabricating both thin (∼100 μm) epidermis and relatively thick dermis is often cumbersome, and most developed phantoms have hardly reflected specific human skin types. The objective of this study was to fabricate skin phantoms with 3D printing technique to emulate various human skin types (I-VI) along with the corresponding optical and mechanical properties for laser tattoo removal. STUDY DESIGN/MATERIALS AND METHODS Both gelatin and agar powders were mixed with coffee and TiO2 particles to fabricate skin phantoms with materials properties for various skin types (I-VI). A 3D printer was employed to precisely control the thickness of each phantom for epidermis and dermis layers. A number of concentrations of the coffee and TiO2 particles were used to determine the degree of absorption and scattering effects in various skin types. The optical properties between 500 and 1,000 nm for the fabricated phantoms were measured by double-integrating spheres with an inverse adding-doubling (IAD) algorithm. Optical coherence tomography (OCT) and rheometer were also utilized to evaluate optical (absorption and reduced scattering coefficients) and mechanical properties (compression modulus) of the fabricated phantoms, respectively. RESULTS Visible color inspections presented that the skin phantoms for types I, III, and VI similarly emulated the color space of the human skin types. The optical property measurements demonstrated that the absorption (μa) and reduced scattering (μ(s')) coefficients decreased with wavelengths. Compared to the human skin type VI, a dermis phantom represented quite equivalent values of μa and μ(s') whereas an epidermis phantom showed up to 30% lower μa but almost identical μ(s') over the wavelengths. The OCT measurements confirmed that the thicknesses of the epidermis and the dermis phantoms were measured to be 138.50 ± 0.01 μm and 0.81 ± 0.04 mm, respectively. The mechanical properties of the phantoms mixed with the agar volume of 40% yielded a compression modulus of 83.7 ± 14.8 kPa, which well corresponded to that of human forearm skin (50-95 kPa). CONCLUSION The 3D printing technique was able to reliably fabricate the double-layered phantoms emulating a variety of skin types (I-VI) along with the comparable optical and mechanical properties. Further investigations will incorporate artificial chromophores into the fabricated skin phantoms to reliably evaluate the new therapeutic wavelengths for laser tattoo removal.
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Affiliation(s)
- Hanna Kim
- Interdisciplinary Program of Marine-Bio, Electrical and Mechanical Engineering, Pukyong National University, Busan, Korea
| | - Nguyen Trung Hau
- Interdisciplinary Program of Marine-Bio, Electrical and Mechanical Engineering, Pukyong National University, Busan, Korea
| | - Yu-Gyeong Chae
- Interdisciplinary Program of Marine-Bio, Electrical and Mechanical Engineering, Pukyong National University, Busan, Korea
| | - Byeong-Il Lee
- Medical Photonics Research Center, Korea Photonics Technology Institute (KOPTI), Gwangju, Korea
| | - Hyun Wook Kang
- Interdisciplinary Program of Marine-Bio, Electrical and Mechanical Engineering, Pukyong National University, Busan, Korea.,Department of Biomedical Engineering and Center for Marine-Integrated Biomedical Technology (BK21 Plus), Pukyong National University, Busan, Korea
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Nadeau KP, Rice TB, Durkin AJ, Tromberg BJ. Multifrequency synthesis and extraction using square wave projection patterns for quantitative tissue imaging. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:116005. [PMID: 26524682 PMCID: PMC5879061 DOI: 10.1117/1.jbo.20.11.116005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 09/09/2015] [Indexed: 05/18/2023]
Abstract
We present a method for spatial frequency domain data acquisition utilizing a multifrequency synthesis and extraction (MSE) method and binary square wave projection patterns. By illuminating a sample with square wave patterns, multiple spatial frequency components are simultaneously attenuated and can be extracted to determine optical property and depth information. Additionally, binary patterns are projected faster than sinusoids typically used in spatial frequency domain imaging (SFDI), allowing for short (millisecond or less) camera exposure times, and data acquisition speeds an order of magnitude or more greater than conventional SFDI. In cases where sensitivity to superficial layers or scattering is important, the fundamental component from higher frequency square wave patterns can be used. When probing deeper layers, the fundamental and harmonic components from lower frequency square wave patterns can be used. We compared optical property and depth penetration results extracted using square waves to those obtained using sinusoidal patterns on an in vivo human forearm and absorbing tube phantom, respectively. Absorption and reduced scattering coefficient values agree with conventional SFDI to within 1% using both high frequency (fundamental) and low frequency (fundamental and harmonic) spatial frequencies. Depth penetration reflectance values also agree to within 1% of conventional SFDI.
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Affiliation(s)
- Kyle P. Nadeau
- Beckman Laser Institute, Laser Microbeam and Medical Program, 1002 Health Sciences Road, Irvine, California 92612 United States
| | - Tyler B. Rice
- Beckman Laser Institute, Laser Associated Sciences, Photonic Incubator, 1002 Health Sciences Road, Irvine, California 92612 United States
| | - Anthony J. Durkin
- Beckman Laser Institute, Laser Microbeam and Medical Program, 1002 Health Sciences Road, Irvine, California 92612 United States
| | - Bruce J. Tromberg
- Beckman Laser Institute, Laser Microbeam and Medical Program, 1002 Health Sciences Road, Irvine, California 92612 United States
- Address all correspondence to: Bruce J. Tromberg, E-mail:
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Glennie DL, Hayward JE, Farrell TJ. Modeling changes in the hemoglobin concentration of skin with total diffuse reflectance spectroscopy. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:035002. [PMID: 25751028 DOI: 10.1117/1.jbo.20.3.035002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 02/16/2015] [Indexed: 05/20/2023]
Abstract
The ability to monitor changes in the concentration of hemoglobin in the blood of the skin in real time is a key component to personalized patient care. Since hemoglobin has a unique absorption spectrum in the visible light range, diffuse reflectance spectroscopy is the most common approach. Although the collection of the diffuse reflectance spectrum with an integrating sphere (IS) has several calibration challenges, this collection method is sufficiently user-friendly that it may be worth overcoming the initial difficulty. Once the spectrum is obtained, it is commonly interpreted with a log-inverse-reflectance (LIR) or “absorbance” analysis that can only accurately monitor changes in the hemoglobin concentration when there are no changes to the nonhemoglobin chromophore concentrations which is not always the case. We address the difficulties associated with collection of the diffuse reflectance spectrum with an IS and propose a model capable of retrieving relative changes in hemoglobin concentration from the visible light spectrum. The model is capable of accounting for concentration changes in the nonhemoglobin chromophores and is first characterized with theoretical spectra and liquid phantoms. The model is then used in comparison with a common LIR analysis on temporal measurements from blanched and reddened human skin.
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Affiliation(s)
- Diana L Glennie
- McMaster University, Department of Medical Physics and Applied Radiation Sciences, 1280 Main Street West, Hamilton, Ontario, L8S 4L8, Canada
| | - Joseph E Hayward
- McMaster University, Department of Medical Physics and Applied Radiation Sciences, 1280 Main Street West, Hamilton, Ontario, L8S 4L8, CanadabJuravinski Cancer Centre, Department of Medical Physics, 699 Concession Street, Hamilton, Ontario, L8V 5C2, Canada
| | - Thomas J Farrell
- McMaster University, Department of Medical Physics and Applied Radiation Sciences, 1280 Main Street West, Hamilton, Ontario, L8S 4L8, CanadabJuravinski Cancer Centre, Department of Medical Physics, 699 Concession Street, Hamilton, Ontario, L8V 5C2, Canada
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Chen YW, Tseng SH. Efficient construction of robust artificial neural networks for accurate determination of superficial sample optical properties. BIOMEDICAL OPTICS EXPRESS 2015; 6:747-60. [PMID: 25798300 PMCID: PMC4361430 DOI: 10.1364/boe.6.000747] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 02/03/2015] [Indexed: 05/18/2023]
Abstract
In general, diffuse reflectance spectroscopy (DRS) systems work with photon diffusion models to determine the absorption coefficient μa and reduced scattering coefficient μs' of turbid samples. However, in some DRS measurement scenarios, such as using short source-detector separations to investigate superficial tissues with comparable μa and μs', photon diffusion models might be invalid or might not have analytical solutions. In this study, a systematic workflow of constructing a rapid, accurate photon transport model that is valid at short source-detector separations (SDSs) and at a wide range of sample albedo is revealed. To create such a model, we first employed a GPU (Graphic Processing Unit) based Monte Carlo model to calculate the reflectance at various sample optical property combinations and established a database at high speed. The database was then utilized to train an artificial neural network (ANN) for determining the sample absorption and reduced scattering coefficients from the reflectance measured at several SDSs without applying spectral constraints. The robustness of the produced ANN model was rigorously validated. We evaluated the performance of a successfully trained ANN using tissue simulating phantoms. We also determined the 500-1000 nm absorption and reduced scattering spectra of in-vivo skin using our ANN model and found that the values agree well with those reported in several independent studies.
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Affiliation(s)
- Yu-Wen Chen
- Department of Photonics, National Cheng-Kung University, Tainan, 701,
Taiwan
| | - Sheng-Hao Tseng
- Department of Photonics, National Cheng-Kung University, Tainan, 701,
Taiwan
- Advanced Optoelectronic Technology Center, National Cheng-Kung University, Tainan, 701,
Taiwan
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Huang J, Zhang S, Gnyawali S, Sen CK, Xu RX. Second derivative multispectral algorithm for quantitative assessment of cutaneous tissue oxygenation. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:036001. [PMID: 25734405 PMCID: PMC4347514 DOI: 10.1117/1.jbo.20.3.036001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 01/20/2015] [Indexed: 05/12/2023]
Abstract
We report a second derivative multispectral algorithm for quantitative assessment of cutaneous tissue oxygen saturation (StO₂). The algorithm is based on a forward model of light transport in multilayered skin tissue and an inverse algorithm for StO₂ reconstruction. Based on the forward simulation results, a parameter of a second derivative ratio (SDR) is derived as a function of cutaneous tissue StO₂. The SDR function is optimized at a wavelength set of 544, 552, 568, 576, 592, and 600 nm so that cutaneous tissue StO₂ can be derived with minimal artifacts by blood concentration, tissue scattering, and melanin concentration. The proposed multispectral StO₂ imaging algorithm is verified in both benchtop and in vivo experiments. The experimental results show that the proposed multispectral imaging algorithm is able to map cutaneous tissue StO₂ in high temporal resolution with reduced measurement artifacts induced by different skin conditions in comparison with other three commercial tissue oxygen measurement systems. These results indicate that the multispectral StO₂ imaging technique has the potential for noninvasive and quantitative assessment of skin tissue oxygenation with a high temporal resolution.
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Affiliation(s)
- Jiwei Huang
- The Ohio State University, Department of Biomedical Engineering, Columbus, Ohio 43210, United States
| | - Shiwu Zhang
- University of Science and Technology of China, Department of Precision Machinery and Precision Instrumentation, Hefei, Anhui 230027, China
| | - Surya Gnyawali
- The Ohio State University, Department of Surgery, Columbus, Ohio 43210, United States
| | - Chandan K. Sen
- The Ohio State University, Department of Surgery, Columbus, Ohio 43210, United States
| | - Ronald X. Xu
- The Ohio State University, Department of Biomedical Engineering, Columbus, Ohio 43210, United States
- University of Science and Technology of China, Department of Precision Machinery and Precision Instrumentation, Hefei, Anhui 230027, China
- Address all correspondence to: Ronald X. Xu, E-mail:
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Hennessy R, Markey MK, Tunnell JW. Impact of one-layer assumption on diffuse reflectance spectroscopy of skin. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:27001. [PMID: 25649627 PMCID: PMC4315872 DOI: 10.1117/1.jbo.20.2.027001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 01/12/2015] [Indexed: 05/11/2023]
Abstract
Diffuse reflectance spectroscopy (DRS) can be used to noninvasively measure skin properties. To extract skin properties from DRS spectra, you need a model that relates the reflectance to the tissue properties. Most models are based on the assumption that skin is homogenous. In reality, skin is composed of multiple layers, and the homogeneity assumption can lead to errors. In this study, we analyze the errors caused by the homogeneity assumption. This is accomplished by creating realistic skin spectra using a computational model, then extracting properties from those spectra using a one-layer model. The extracted parameters are then compared to the parameters used to create the modeled spectra. We used a wavelength range of 400 to 750 nm and a source detector separation of 250 μm. Our results show that use of a one-layer skin model causes underestimation of hemoglobin concentration [Hb] and melanin concentration [mel]. Additionally, the magnitude of the error is dependent on epidermal thickness. The one-layer assumption also causes [Hb] and [mel] to be correlated. Oxygen saturation is overestimated when it is below 50% and underestimated when it is above 50%. We also found that the vessel radius factor used to account for pigment packaging is correlated with epidermal thickness.
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Affiliation(s)
- Ricky Hennessy
- The University of Texas, Biomedical Engineering, 107 West Dean Keeton Street, Austin, Texas 78712, United States
- Address all correspondence to: Ricky Hennessy, E-mail:
| | - Mia K. Markey
- The University of Texas, Biomedical Engineering, 107 West Dean Keeton Street, Austin, Texas 78712, United States
- University of Texas MD Anderson Cancer Center, Imaging Physics, 1515 Holcombe Boulevard, Houston, Texas 77030, United States
| | - James W. Tunnell
- University of Texas MD Anderson Cancer Center, Imaging Physics, 1515 Holcombe Boulevard, Houston, Texas 77030, United States
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Hsu CK, Tzeng SY, Yang CC, Lee JYY, Huang LLH, Chen WR, Hughes M, Chen YW, Liao YK, Tseng SH. Non-invasive evaluation of therapeutic response in keloid scar using diffuse reflectance spectroscopy. BIOMEDICAL OPTICS EXPRESS 2015; 6:390-404. [PMID: 25780731 PMCID: PMC4354586 DOI: 10.1364/boe.6.000390] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 12/15/2014] [Accepted: 01/02/2015] [Indexed: 05/31/2023]
Abstract
The pathogenesis and ideal treatment of keloid are still largely unknown, and it is essential to develop an objective assessment of keloid severity to evaluate the therapeutic response. We previously reported that our diffuse reflectance spectroscopy (DRS) system could assist clinicians in understanding the functional and structural condition of keloid scars. The purpose of this study was to understand clinical applicability of our DRS system on evaluating the scar severity and therapeutic response of keloid. We analyzed 228 spectral data from 71 subjects with keloid scars. The scars were classified into mild (0-3), moderate (4-7) and severe (8-11) according to the Vancouver scar scale. We found that as the severity of the scar increased, collagen concentration and water content increased, and the reduced scattering coefficient at 800 nm and oxygen saturation (SaO2) decreased. Using the DRS system, we found that collagen bundles aligned in a specific direction in keloid scars, but not in normal scars. Water content and SaO2 may be utilized as reliable parameters for evaluating the therapeutic response of keloid. In conclusion, the results obtained here suggest that the DRS has potential as an objective technique with which to evaluate keloid scar severity. In addition, it may be useful as a tool with which to track longitudinal response of scars in response to various therapeutic interventions.
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Affiliation(s)
- Chao-Kai Hsu
- Department of Dermatology, National Cheng Kung University College of Medicine and Hospital, Tainan 701,
Taiwan
- Institute of Clinical Medicine, National Cheng Kung University College of Medicine and Hospital, Tainan 701,
Taiwan
- International Research Center of Wound Repair and Regeneration, National Cheng Kung University, Tainan 701,
Taiwan
- These authors contributed equally to this work and should be considered co-first authors
| | - Shih-Yu Tzeng
- Department of Photonics, National Cheng-Kung University, Tainan 701,
Taiwan
- Advanced Optoelectronic Technology Center, National Cheng-Kung University, Tainan 701,
Taiwan
- These authors contributed equally to this work and should be considered co-first authors
| | - Chao-Chun Yang
- Department of Dermatology, National Cheng Kung University College of Medicine and Hospital, Tainan 701,
Taiwan
- Institute of Clinical Medicine, National Cheng Kung University College of Medicine and Hospital, Tainan 701,
Taiwan
- International Research Center of Wound Repair and Regeneration, National Cheng Kung University, Tainan 701,
Taiwan
| | - Julia Yu-Yun Lee
- Department of Dermatology, National Cheng Kung University College of Medicine and Hospital, Tainan 701,
Taiwan
- International Research Center of Wound Repair and Regeneration, National Cheng Kung University, Tainan 701,
Taiwan
| | | | - Wan-Rung Chen
- Department of Dermatology, National Cheng Kung University College of Medicine and Hospital, Tainan 701,
Taiwan
| | - Michael Hughes
- International Research Center of Wound Repair and Regeneration, National Cheng Kung University, Tainan 701,
Taiwan
| | - Yu-Wen Chen
- Department of Photonics, National Cheng-Kung University, Tainan 701,
Taiwan
- Advanced Optoelectronic Technology Center, National Cheng-Kung University, Tainan 701,
Taiwan
| | - Yu-Kai Liao
- Department of Photonics, National Cheng-Kung University, Tainan 701,
Taiwan
- Advanced Optoelectronic Technology Center, National Cheng-Kung University, Tainan 701,
Taiwan
| | - Sheng-Hao Tseng
- Department of Photonics, National Cheng-Kung University, Tainan 701,
Taiwan
- Advanced Optoelectronic Technology Center, National Cheng-Kung University, Tainan 701,
Taiwan
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40
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Hung CH, Chou TC, Hsu CK, Tseng SH. Broadband absorption and reduced scattering spectra of in-vivo skin can be noninvasively determined using δ-P1 approximation based spectral analysis. BIOMEDICAL OPTICS EXPRESS 2015; 6:443-56. [PMID: 25780735 PMCID: PMC4354575 DOI: 10.1364/boe.6.000443] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 12/04/2014] [Accepted: 01/02/2015] [Indexed: 05/16/2023]
Abstract
Previously, we revealed that a linear gradient line source illumination (LGLSI) geometry could work with advanced diffusion models to recover the sample optical properties at wavelengths where sample absorption and reduced scattering were comparable. In this study, we employed the LGLSI geometry with a broadband light source and utilized the spectral analysis to determine the broadband absorption and scattering spectra of turbid samples in the wavelength range from 650 to 1350 nm. The performance of the LGLSI δ-P1 diffusion model based spectral analysis was evaluated using liquid phantoms, and it was found that the sample optical properties could be properly recovered even at wavelengths above 1000 nm where μs' to μa ratios were in the range between 1 to 20. Finally, we will demonstrate the use of our system for recovering the 650 to 1350 nm absorption and scattering spectra of in-vivo human skin. We expect this system can be applied to study deep vessel dilation induced hemoglobin concentration variation and determine the water and lipid concentrations of in-vivo skin in clinical settings in the future.
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Affiliation(s)
- Cheng-Hung Hung
- Department of Photonics, National Cheng-Kung University, Tainan, 701,
Taiwan
| | - Ting-Chun Chou
- Department of Photonics, National Cheng-Kung University, Tainan, 701,
Taiwan
| | - Chao-Kai Hsu
- Department of Dermatology, National Cheng Kung University College of Medicine and Hospital, Tainan, 701,
Taiwan
| | - Sheng-Hao Tseng
- Department of Photonics, National Cheng-Kung University, Tainan, 701,
Taiwan
- Advanced Optoelectronic Technology Center, National Cheng-Kung University, Tainan, 701,
Taiwan
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41
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Schleusener J, Gluszczynska P, Reble C, Gersonde I, Helfmann J, Cappius HJ, Fluhr JW, Meinke MC. Perturbation factors in the clinical handling of a fiber-coupled Raman probe for cutaneous in vivo diagnostic Raman spectroscopy. APPLIED SPECTROSCOPY 2015; 69:243-256. [PMID: 25588117 DOI: 10.1366/14-07482] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The application of fiber-coupled Raman probes for the discrimination of cancerous and normal skin has the advantage of a non-invasive in vivo application, easy clinical handling, and access to the majority of body sites, which would otherwise be limited by stationary Raman microscopes. Nevertheless, including optical fibers and miniaturizing optical components, as well as measuring in vivo, involves the sensibility to external perturbation factors that could introduce artifacts to the acquired Raman spectra and thereby potentially reduce classification performance. In this study, typical perturbation factors of Raman measurements with a Raman fiber probe, optimized for clinical in vivo discrimination of skin cancer, were investigated experimentally. Measurements were performed under standardized conditions in clinical settings in vivo on human skin, as well as ex vivo on porcine ears. Raman spectra were analyzed in the fingerprint region between 1150 and 1730 cm(-1) using principal component analysis. The largest artifacts in the Raman spectra were found in measurements performed under the influence of strong ambient light conditions as well as after miscellaneous pre-treatments to the skin, such as use of a permanent marker or a sunscreen. Minor influences were also found in measurements using H2O immersion and when varying the probe contact force. The effect of reasonable variation of the fiber-bending radius was found to be of negligible impact. The influence of measurements on hairy or sun-exposed body sites, as well as inter-subject variation, was also investigated. The presented results may serve as a guide to avoid negative effects during the process of data acquisition and so avoid misclassification in tumor discrimination.
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Affiliation(s)
- Johannes Schleusener
- Laser- und Medizin- Technologie Berlin (LMTB), Fabeckstrasse 60-62, 14195 Berlin, Germany
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Bregar M, Cugmas B, Naglic P, Hartmann D, Pernuš F, Likar B, Bürmen M. Properties of contact pressure induced by manually operated fiber-optic probes. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:127002. [PMID: 26720880 DOI: 10.1117/1.jbo.20.12.127002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 11/17/2015] [Indexed: 05/13/2023]
Abstract
We assess the properties of contact pressure applied by manually operated fiber-optic probes as a function of the operator, probe contact area, and sample stiffness. First, the mechanical properties of human skin sites with different skin structures, thicknesses, and underlying tissues were studied by in vivo indentation tests. According to the obtained results, three different homogeneous silicone skin phantoms were created to encompass the observed range of mechanical properties. The silicon phantoms were subsequently used to characterize the properties of the contact pressure by 10 experienced probe operators employing fiber-optic probes with different contact areas. A custom measurement system was used to collect the time-lapse of diffuse reflectance and applied contact pressure. The measurements were characterized by a set of features describing the transient and steady-state properties of the contact pressure and diffuse reflectance in terms of rise time, optical coupling, average value, and variability. The average applied contact pressure and contact pressure variability were found to significantly depend on the probe operator, probe contact area, and surprisingly also on the sample stiffness. Based on the presented results, we propose a set of practical guidelines for operators of manual probes.
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Affiliation(s)
- Maksimilijan Bregar
- University of Ljubljana, Laboratory of Imaging Technologies, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Blaž Cugmas
- University of Ljubljana, Laboratory of Imaging Technologies, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Peter Naglic
- University of Ljubljana, Laboratory of Imaging Technologies, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Daniela Hartmann
- Ludwig-Maximilian University, Department of Dermatology and Allergology, Frauenlobstrasse 9-11, 80337 Munich, Germany
| | - Franjo Pernuš
- University of Ljubljana, Laboratory of Imaging Technologies, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Boštjan Likar
- University of Ljubljana, Laboratory of Imaging Technologies, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Miran Bürmen
- University of Ljubljana, Laboratory of Imaging Technologies, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
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43
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Evans S, Baylis S, Carabott R, Jones M, Kelson Z, Marsh N, Payne-James J, Ramadani J, Vanezis P, Kemp A. Guidelines for photography of cutaneous marks and injuries: a multi-professional perspective. J Vis Commun Med 2014; 37:3-12. [DOI: 10.3109/17453054.2014.911152] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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44
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Truong BCQ, Tuan HD, Nguyen HT. Near-infrared parameters extraction: A potential method to detect skin cancer. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2013:33-6. [PMID: 24109617 DOI: 10.1109/embc.2013.6609430] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The wavelength-dependent absorption coefficients can be used to analyse optical properties of human skin. Existing absorption models for narrow ranges in the visible and near infrared are insufficient to simultaneously incorporate the spectral contrast produced by differences in chromophores, water and lipid content of skin tissue into skin cancer detection. In the broad range up to 1600 nm, recent analysis approaches for absorption spectra do not consistently provide significant differences between healthy and cancerous skins. We propose an absorption model to fit the absorption coefficient spectra of skin samples over the range from 400 nm to 1600 nm and an advanced algorithm to find the optimal estimation. The extracted parameters of this model are analysed by a statistical t-test. The test results demonstrate the significant differences between all pairs of tumour-normal skin. Therefore, our approach has strong potential for early skin cancer detection using near infrared spectroscopy (NIRS).
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45
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Soni S, Tyagi H, Taylor RA, Kumar A. Role of optical coefficients and healthy tissue-sparing characteristics in gold nanorod-assisted thermal therapy. Int J Hyperthermia 2013; 29:87-97. [PMID: 23311382 DOI: 10.3109/02656736.2012.753162] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
PURPOSE This study seeks to define parameters for gold nanorod assisted thermal therapy, to achieve the thermal ablation temperature (50-60°C) in the tumour region and spare healthy tissue surrounding the tumour. Also, a criterion for size selection of gold nanorods is described based on the role of optical coefficients. THEORY AND METHODS In this study a tissue domain (comprising a 3 mm tumour and 7 mm of surrounding healthy tissue) embedded with gold nanorods is irradiated with electromagnetic radiation within the therapeutic wavelength band. Optical interaction is captured using light scattering theory (Mie-electrostatic approach). The resulting temperature field is evaluated using Penne's bioheat model. The effect of key parameters, namely irradiation intensity, irradiation duration and volume fraction, on tissue temperature is also modelled numerically. RESULTS With increasing nanorod diameter - from 5 nm to 15 nm - the scattering coefficient increases ∼76 times as compared to a 1.7-fold increase in absorption coefficient. Scattering is considerably minimised by having smaller gold nanorods of 5 nm diameter. For this study, gold nanorods of 5 nm diameter and volume fraction 0.001%, irradiated with 50 W/m(2)-nm for 250 s ablated the tumour as well as spare healthy tissue 2 mm beyond the tumour region. CONCLUSION Overall it may be concluded that tumour ablation as well as surrounding healthy tissue-sparing (within millimetres immediately adjacent to the tumour) can be achieved through a combination of specified parameters, namely diameter and volume fraction of gold nanorods, irradiation intensity and duration.
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Affiliation(s)
- Sanjeev Soni
- School of Mechanical, Materials and Energy Engineering, Indian Institute of Technology Ropar, Rupnagar, Punjab, India
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46
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Saager RB, Hassan KM, Kondru C, Durkin AJ, Kelly KM. Quantitative near infrared spectroscopic analysis of Q-Switched Nd:YAG treatment of generalized argyria. Lasers Surg Med 2013; 45:15-21. [PMID: 23322674 DOI: 10.1002/lsm.22084] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/18/2012] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND OBJECTIVE Generalized argyria is a blue-gray hyperpigmentation of the skin resulting from ingestion or application of silver compounds, such as silver colloid. Case reports have noted improvement after Q-Switched Neodymium-Yttrium Aluminum Garnet laser (1,064 nm QS Nd:YAG) laser treatment to small surface areas. No reports have objectively monitored laser treatment of generalized argyria over large areas of skin, nor have long-term outcomes been evaluated. STUDY DESIGN/MATERIALS AND METHODS An incremental treatment plan was developed for a subject suffering from argyria. A quantitative near infrared spectroscopic measurement technique was employed to non-invasively analyze tissue-pigment characteristics pre- and post-laser treatment. Post-treatment measurements were collected at weeks 1, 2, 3, and 4, and again at 1 year. RESULTS Immediate apparent removal of pigment was observed with 1 Q-switched 1,064 nm Nd:YAG laser treatment (3-6 mm spot; 0.8-2 J/cm(2) ) per area. Entire face, neck, upper chest, and arms were treated over multiple sessions. Treatments were very painful and general anesthesia was utilized in order to treat large areas. Near-infrared spectroscopy was used to characterize and quantify the concentration of silver particles in the dermis based on the absorption features of the silver particles as well as the optical scattering effects they impart. We were able to estimate that there was, on average, 0.042 mg/ml concentration of silver prior to treatment and that these levels went below the minimum detectable limit of the instrument post-treatment. There was no recurrence of discoloration over the 1-year study period. CONCLUSION QS 1,064 nm laser treatment of argyria is a viable method to restore normal skin pigmentation with no evidence of recurrence over study period. Quantitative spectroscopic measurements: (1) confirmed dyspigmentation was due to silver, (2) validated our clinical assessment of no recurrence up to 1-year post-treatment, and (3) indicated no collateral tissue damage with treatments.
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Affiliation(s)
- Rolf B Saager
- Beckman Laser Institute and Medical Clinic, University of California-Irvine, Irvine, California 92617, USA
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47
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Saager RB, Hassan KM, Kondru C, Durkin AJ, Kelly KM. Quantitative near infrared spectroscopic analysis of Q-Switched Nd:YAG treatment of generalized argyria. Lasers Surg Med 2013. [PMID: 23322674 DOI: 10.1002/lsm.v45.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
BACKGROUND AND OBJECTIVE Generalized argyria is a blue-gray hyperpigmentation of the skin resulting from ingestion or application of silver compounds, such as silver colloid. Case reports have noted improvement after Q-Switched Neodymium-Yttrium Aluminum Garnet laser (1,064 nm QS Nd:YAG) laser treatment to small surface areas. No reports have objectively monitored laser treatment of generalized argyria over large areas of skin, nor have long-term outcomes been evaluated. STUDY DESIGN/MATERIALS AND METHODS An incremental treatment plan was developed for a subject suffering from argyria. A quantitative near infrared spectroscopic measurement technique was employed to non-invasively analyze tissue-pigment characteristics pre- and post-laser treatment. Post-treatment measurements were collected at weeks 1, 2, 3, and 4, and again at 1 year. RESULTS Immediate apparent removal of pigment was observed with 1 Q-switched 1,064 nm Nd:YAG laser treatment (3-6 mm spot; 0.8-2 J/cm(2) ) per area. Entire face, neck, upper chest, and arms were treated over multiple sessions. Treatments were very painful and general anesthesia was utilized in order to treat large areas. Near-infrared spectroscopy was used to characterize and quantify the concentration of silver particles in the dermis based on the absorption features of the silver particles as well as the optical scattering effects they impart. We were able to estimate that there was, on average, 0.042 mg/ml concentration of silver prior to treatment and that these levels went below the minimum detectable limit of the instrument post-treatment. There was no recurrence of discoloration over the 1-year study period. CONCLUSION QS 1,064 nm laser treatment of argyria is a viable method to restore normal skin pigmentation with no evidence of recurrence over study period. Quantitative spectroscopic measurements: (1) confirmed dyspigmentation was due to silver, (2) validated our clinical assessment of no recurrence up to 1-year post-treatment, and (3) indicated no collateral tissue damage with treatments.
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Affiliation(s)
- Rolf B Saager
- Beckman Laser Institute and Medical Clinic, University of California-Irvine, Irvine, California 92617, USA
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48
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Tseng SH, Hsu CK, Yu-Yun Lee J, Tzeng SY, Chen WR, Liaw YK. Noninvasive evaluation of collagen and hemoglobin contents and scattering property of in vivo keloid scars and normal skin using diffuse reflectance spectroscopy: pilot study. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:077005. [PMID: 22894518 DOI: 10.1117/1.jbo.17.7.077005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Collagen is a rich component in skin that provides skin structure integrity; however, its contribution to the absorption and scattering properties of various types of skin has not been extensively studied. We considered the contribution of the collagen to the absorption spectrum of in vivo normal skin and keloids of 12 subjects derived from our diffuse reflectance spectroscopy (DRS) system in the wavelength range from 550 to 860 nm. It was found that the collagen concentration, the hemoglobin oxygen saturation, and the reduced scattering coefficient of keloids were remarkably different from that of normal skin. Our results suggest that our DRS system could assist clinicians in understanding the functional and structural condition of keloid scars. In the future, we will evaluate the accuracy of our system in the keloid diagnosis and investigate the applicability of our system for other skin-collagen-related studies.
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Affiliation(s)
- Sheng-Hao Tseng
- National Cheng-Kung University, Department of Photonics, Tainan 701, Taiwan.
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49
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Holton SE, Walsh MJ, Kajdacsy-Balla A, Bhargava R. Label-free characterization of cancer-activated fibroblasts using infrared spectroscopic imaging. Biophys J 2011; 101:1513-21. [PMID: 21943433 DOI: 10.1016/j.bpj.2011.07.055] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2011] [Revised: 07/12/2011] [Accepted: 07/14/2011] [Indexed: 11/18/2022] Open
Abstract
Glandular tumors arising in epithelial cells comprise the majority of solid human cancers. Glands are supported by stroma, which is activated in the proximity of a tumor. Activated stroma is often characterized by the molecular expression of α-smooth muscle actin (α-SMA) within fibroblasts. However, the precise spatial and temporal evolution of chemical changes in fibroblasts upon epithelial tumor signaling is poorly understood. Here we report a label-free method to characterize fibroblast changes by using Fourier transform infrared spectroscopic imaging and comparing spectra with α-SMA expression in primary normal human fibroblasts. We recorded the fibroblast activation process by spectroscopic imaging using increasingly tissue-like conditions: 1), stimulation with the growth factor TGFβ1; 2), coculture with MCF-7 human breast cancerous epithelial cells in Transwell coculture; and 3), coculture with MCF-7 in three-dimensional cell culture. Finally, we compared the spectral signatures of stromal transformation with normal and malignant human breast tissue biopsies. The results indicate that this approach reveals temporally complex spectral changes and thus provides a richer assessment than simple molecular imaging based on α-SMA expression. Some changes are conserved across culture conditions and in human tissue, providing a label-free method to monitor stromal transformations.
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Affiliation(s)
- S E Holton
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
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50
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Tseng SH, Hou MF. Efficient determination of the epidermal optical properties using a diffusion model-based approach: Monte Carlo studies. JOURNAL OF BIOMEDICAL OPTICS 2011; 16:087007. [PMID: 21895334 DOI: 10.1117/1.3609821] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In our previous studies, we have shown that the diffusing probe geometry can be used in conjunction with a two-layer diffusion model to accurately recover the absorption and scattering properties of skin in vivo. By modifying the original design to the diffusing probe with planar source (DPPS) geometry, we have also demonstrated that the efficiency of the accompanying multilayer diffusion model is comparable to that of a standard semi-infinite diffusion model; thus, precise quantification of superficial tissue optical properties in real time using a diffusion model becomes possible. In this study, the performance of the DPPS diffusion model is evaluated using Monte Carlo simulations and phantom measurements. It is found that the DPPS geometry is advantageous over the conventional planar source illumination geometry in interrogating superficial volumes of samples. In addition, our simulation results have shown that the DPPS geometry is capable of accurately recovering the optical properties of 50-μm thick epidermis and could be very useful in detecting cutaneous melanoma that has a radius as small as 250 μm.
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Affiliation(s)
- Sheng-Hao Tseng
- National Cheng-Kung University, Department of Photonics, Tainan 701, Taiwan.
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