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Parravicini J, Tomaselli A, Hasani E, Tomassini D, Manfredi N, Tartara L. Practical two-photon-absorption cross sections and spectra of eosin and hematoxylin. JOURNAL OF BIOPHOTONICS 2020; 13:e202000141. [PMID: 32713128 DOI: 10.1002/jbio.202000141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 07/20/2020] [Accepted: 07/21/2020] [Indexed: 06/11/2023]
Abstract
We experimentally investigate the two-photon absorption cross sections and spectra of eosin and hematoxylin for applications in nonlinear microscopy. The experiments are carried out on pure samples of the two dyes in DI-water solvent with different concentrations, in the typical range employed in standard staining procedures. Nonlinear fluorescence is excited by a line-shaped beam emitted by a Ti:Sapphire mode-locked laser in the wavelength range from 740 to 880 nm and is detected through a microscope setup. The two-photon absorption spectral response is systematically analyzed and discussed. Finally, the staining is applied on biological tissue samples, which are imaged by two-photon microscopy. Our results show that the employed dyes are fully suitable for applications in nonlinear imaging.
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Affiliation(s)
- Jacopo Parravicini
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Milan, Italy
- Erasmus Centre for Innovation, Erasmus University Rotterdam, Rotterdam, The Netherlands
| | - Alessandra Tomaselli
- Dipartimento di Ingegneria Industriale e dell'Informazione, Università di Pavia, Pavia, Italy
| | - Elton Hasani
- Dipartimento di Ingegneria Industriale e dell'Informazione, Università di Pavia, Pavia, Italy
- Bright Solutions, Cura Carpignano, Italy
| | - Daniela Tomassini
- Dipartimento di Ingegneria Industriale e dell'Informazione, Università di Pavia, Pavia, Italy
- BiMind, Jesi, Italy
| | - Norberto Manfredi
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Milan, Italy
- Milano-Bicocca Research Unit, INSTM, Milan, Italy
| | - Luca Tartara
- Dipartimento di Ingegneria Industriale e dell'Informazione, Università di Pavia, Pavia, Italy
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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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Halicek M, Fabelo H, Ortega S, Callico GM, Fei B. In-Vivo and Ex-Vivo Tissue Analysis through Hyperspectral Imaging Techniques: Revealing the Invisible Features of Cancer. Cancers (Basel) 2019; 11:E756. [PMID: 31151223 PMCID: PMC6627361 DOI: 10.3390/cancers11060756] [Citation(s) in RCA: 96] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 05/20/2019] [Accepted: 05/24/2019] [Indexed: 12/27/2022] Open
Abstract
In contrast to conventional optical imaging modalities, hyperspectral imaging (HSI) is able to capture much more information from a certain scene, both within and beyond the visual spectral range (from 400 to 700 nm). This imaging modality is based on the principle that each material provides different responses to light reflection, absorption, and scattering across the electromagnetic spectrum. Due to these properties, it is possible to differentiate and identify the different materials/substances presented in a certain scene by their spectral signature. Over the last two decades, HSI has demonstrated potential to become a powerful tool to study and identify several diseases in the medical field, being a non-contact, non-ionizing, and a label-free imaging modality. In this review, the use of HSI as an imaging tool for the analysis and detection of cancer is presented. The basic concepts related to this technology are detailed. The most relevant, state-of-the-art studies that can be found in the literature using HSI for cancer analysis are presented and summarized, both in-vivo and ex-vivo. Lastly, we discuss the current limitations of this technology in the field of cancer detection, together with some insights into possible future steps in the improvement of this technology.
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Affiliation(s)
- Martin Halicek
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080, USA.
- Department of Biomedical Engineering, Emory University and The Georgia Institute of Technology, 1841 Clifton Road NE, Atlanta, GA 30329, USA.
| | - Himar Fabelo
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080, USA.
- Institute for Applied Microelectronics (IUMA), University of Las Palmas de Gran Canaria (ULPGC), 35017 Las Palmas de Gran Canaria, Spain.
| | - Samuel Ortega
- Institute for Applied Microelectronics (IUMA), University of Las Palmas de Gran Canaria (ULPGC), 35017 Las Palmas de Gran Canaria, Spain.
| | - Gustavo M Callico
- Institute for Applied Microelectronics (IUMA), University of Las Palmas de Gran Canaria (ULPGC), 35017 Las Palmas de Gran Canaria, Spain.
| | - Baowei Fei
- Department of Bioengineering, The University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX 75080, USA.
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, 5323 Harry Hine Blvd, Dallas, TX 75390, USA.
- Department of Radiology, University of Texas Southwestern Medical Center, 5323 Harry Hine Blvd, Dallas, TX 75390, USA.
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Castellanos MR, Nehru VM, Pirog EC, Optiz L. Fluorescence microscopy of H&E stained cervical biopsies to assist the diagnosis and grading of CIN. Pathol Res Pract 2018; 214:605-611. [PMID: 29627221 DOI: 10.1016/j.prp.2018.03.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 03/22/2018] [Indexed: 12/27/2022]
Abstract
BACKGROUND Prevention of cervical cancer is based upon the accurate diagnosis and grading of cervical lesions identified during screening. The pathological classification of cervical intraepithelial neoplasia (CIN) is problematic, as it relies on subjective criteria and is known to have high interobserver variability and low reproducibility. These limitations can result in either over or under treatment of patients. Biomarkers to improve CIN diagnosis have not overcome all these challenges. MAIN BODY Here we review the use of a promising optical imaging method using eosin-based fluorescence spectroscopy. This technique is able to perform fluorescent analysis of cervical biopsies directly from hematoxylin and eosin (H&E) stained tissues. Eosin is a brominated derivative of fluorescein. Fluorescence characteristics of protein-eosin complexes can demonstrate tissue changes associated with dysplasia and cancer. In this article we review the progress made towards developing eosin-based fluorescence spectroscopy. We describe the various morphologies seen among the CIN grades with this optical method and highlight the progress made to quantitate the spectral image characteristics. CONCLUSION Eosin-based fluorescence spectroscopy can be used to directly examine H&E stained tissue slides. Relevant areas can be imaged and spectral analysis done to obtain objective data to identify and grade cervical lesions.
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Affiliation(s)
- Mario R Castellanos
- Division of Research, Department of Medicine, Staten Island University Hospital - Northwell Health, 475 Seaview Ave, Staten Island, NY 10305, USA.
| | - Vijeyaluxmy Motilal Nehru
- Division of Research, Department of Medicine, Staten Island University Hospital - Northwell Health, 475 Seaview Ave, Staten Island, NY 10305, USA.
| | - Edyta C Pirog
- Department of Pathology, Weill Cornell Medical College, 525 East 68th Street, New York, NY 10065, USA.
| | - Lynne Optiz
- Department of Pathology and Laboratory Medicine, Staten Island University Hospital - Northwell Health, 475 Seaview Ave, Staten Island, NY 10305, USA.
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Wilson RH, Vishwanath K, Mycek MA. Optical methods for quantitative and label-free sensing in living human tissues: principles, techniques, and applications. ADVANCES IN PHYSICS 2016; 1:523-543. [PMID: 28824194 PMCID: PMC5560608 DOI: 10.1080/23746149.2016.1221739] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We present an overview of quantitative and label-free optical methods used to characterize living biological tissues, with an emphasis on emerging applications in clinical tissue diagnostics. Specifically, this review focuses on diffuse optical spectroscopy, imaging, and tomography, optical coherence-based techniques, and non-linear optical methods for molecular imaging. The potential for non- or minimally-invasive assessment, quantitative diagnostics, and continuous monitoring enabled by these tissue-optics technologies provides significant promise for continued clinical translation.
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Affiliation(s)
- Robert H. Wilson
- Beckman Laser Institute, University of California, Irvine, Irvine, CA, USA
| | | | - Mary-Ann Mycek
- Department of Biomedical Engineering, Applied Physics Program, University of Michigan, Ann Arbor, MI, USA
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Kholodtsova MN, Daul C, Loschenov VB, Blondel WCPM. Spatially and spectrally resolved particle swarm optimization for precise optical property estimation using diffuse-reflectance spectroscopy. OPTICS EXPRESS 2016; 24:12682-12700. [PMID: 27410289 DOI: 10.1364/oe.24.012682] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This paper presents a new approach to estimate optical properties (absorption and scattering coefficients µa and µs) of biological tissues from spatially-resolved spectroscopy measurements. A Particle Swarm Optimization (PSO)-based algorithm was implemented and firstly modified to deal with spatial and spectral resolutions of the data, and to solve the corresponding inverse problem. Secondly, the optimization was improved by fitting exponential decays to the two best points among all clusters of the "particles" randomly distributed all over the parameter space (µs, µa) of possible solutions. The consequent acceleration of all the groups of particles to the "best" curve leads to significant error decrease in the optical property estimation. The study analyzes the estimated optical property error as a function of the various PSO parameter combinations, and several performance criteria such as the cost-function error and the number of iterations in the algorithms proposed. The final one led to error values between ground truth and estimated values of µs and µa less than 6%.
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Castellanos MR, Szerszen A, Gundry S, Pirog EC, Maiman M, Rajupet S, Gomez JP, Davidov A, Debata PR, Banerjee P, Fata JE. Diagnostic imaging of cervical intraepithelial neoplasia based on hematoxylin and eosin fluorescence. Diagn Pathol 2015. [PMID: 26204927 PMCID: PMC4513699 DOI: 10.1186/s13000-015-0343-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Background Pathological classification of cervical intraepithelial neoplasia (CIN) is problematic as it relies on subjective criteria. We developed an imaging method that uses spectroscopy to assess the fluorescent intensity of cervical biopsies derived directly from hematoxylin and eosin (H&E) stained tissues. Methods Archived H&E slides were identified containing normal cervical tissue, CIN I, and CIN III cases, from a Community Hospital and an Academic Medical Center. Cases were obtained by consensus review of at least 2 senior pathologists. Images from H&E slides were captured first with bright field illumination and then with fluorescent illumination. We used a Zeiss Axio Observer Z1 microscope and an AxioVision 4.6.3-AP1 camera at excitation wavelength of 450–490 nm with emission captured at 515–565 nm. The 32-bit grayscale fluorescence images were used for image analysis. Results We reviewed 108 slides: 46 normal, 33 CIN I and 29 CIN III. Fluorescent intensity increased progressively in normal epithelial tissue as cells matured and advanced from the basal to superficial regions of the epithelium. In CIN I cases this change was less prominent as compared to normal. In high grade CIN lesions, there was a slight or no increase in fluorescent intensity. All groups examined were statistically different. Conclusion Presently, there are no markers to help in classification of CIN I-III lesions. Our imaging method may complement standard H&E pathological review and provide objective criteria to support the CIN diagnosis.
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Affiliation(s)
- Mario R Castellanos
- Division of Medical Women's Health, Staten Island University Hospital, 475 Seaview Ave, Staten Island, NY, 10305, USA.
| | - Anita Szerszen
- Division of Geriatrics, Department of Medicine, Staten Island University Hospital, 475 Seaview Ave, Staten Island, NY, 10305, USA
| | - Stephen Gundry
- Electrical Engineering Doctoral Program, City College of New York, The City University of New York, 160 Convent Avenue, New York, NY, 10031, USA
| | - Edyta C Pirog
- Department of Pathology, Weill Cornell Medical College, 525 East 68th Street, New York, NY, 10065, USA
| | - Mitchell Maiman
- Department of Obstetrics and Gynecology, Staten Island University Hospital, 475 Seaview Ave, Staten Island, NY, 10305, USA
| | - Sritha Rajupet
- Division of Medical Women's Health, Staten Island University Hospital, 475 Seaview Ave, Staten Island, NY, 10305, USA
| | - John Paul Gomez
- Division of Medical Women's Health, Staten Island University Hospital, 475 Seaview Ave, Staten Island, NY, 10305, USA
| | - Adi Davidov
- Department of Obstetrics and Gynecology, Staten Island University Hospital, 475 Seaview Ave, Staten Island, NY, 10305, USA
| | - Priya Ranjan Debata
- Department of Chemistry, College of Staten Island, 2800 Victory Blvd., Staten Island, NY, 10314, USA
| | - Probal Banerjee
- Department of Chemistry, College of Staten Island, 2800 Victory Blvd., Staten Island, NY, 10314, USA
| | - Jimmie E Fata
- Department of Biology, College of Staten Island, 2800 Victory Blvd., Staten Island, NY, 10314, USA.
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Light scattering properties vary across different regions of the adult mouse brain. PLoS One 2013; 8:e67626. [PMID: 23874433 PMCID: PMC3706487 DOI: 10.1371/journal.pone.0067626] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 05/21/2013] [Indexed: 11/19/2022] Open
Abstract
Recently developed optogenetic tools provide powerful approaches to optically excite or inhibit neural activity. In a typical in-vivo experiment, light is delivered to deep nuclei via an implanted optical fiber. Light intensity attenuates with increasing distance from the fiber tip, determining the volume of tissue in which optogenetic proteins can successfully be activated. However, whether and how this volume of effective light intensity varies as a function of brain region or wavelength has not been systematically studied. The goal of this study was to measure and compare how light scatters in different areas of the mouse brain. We delivered different wavelengths of light via optical fibers to acute slices of mouse brainstem, midbrain and forebrain tissue. We measured light intensity as a function of distance from the fiber tip, and used the data to model the spread of light in specific regions of the mouse brain. We found substantial differences in effective attenuation coefficients among different brain areas, which lead to substantial differences in light intensity demands for optogenetic experiments. The use of light of different wavelengths additionally changes how light illuminates a given brain area. We created a brain atlas of effective attenuation coefficients of the adult mouse brain, and integrated our data into an application that can be used to estimate light scattering as well as required light intensity for optogenetic manipulation within a given volume of tissue.
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Lee SY, Lloyd WR, Chandra M, Wilson RH, McKenna B, Simeone D, Scheiman J, Mycek MA. Characterizing human pancreatic cancer precursor using quantitative tissue optical spectroscopy. BIOMEDICAL OPTICS EXPRESS 2013; 4:2828-34. [PMID: 24409383 PMCID: PMC3862164 DOI: 10.1364/boe.4.002828] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 09/29/2013] [Accepted: 10/31/2013] [Indexed: 05/20/2023]
Abstract
In a pilot study, multimodal optical spectroscopy coupled with quantitative tissue-optics models distinguished intraductal papillary mucinous neoplasm (IPMN), a common precursor to pancreatic cancer, from normal tissues in freshly excised human pancreas. A photon-tissue interaction (PTI) model extracted parameters associated with cellular nuclear size and refractive index (from reflectance spectra) and extracellular collagen content (from fluorescence spectra). The results suggest that tissue optical spectroscopy has the potential to characterize pre-cancerous neoplasms in human pancreatic tissues.
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Affiliation(s)
- Seung Yup Lee
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109-2099, USA
| | - William R. Lloyd
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109-2099, USA
| | - Malavika Chandra
- Applied Physics Program, University of Michigan, Ann Arbor, MI 48109-1040, USA
| | - Robert H. Wilson
- Applied Physics Program, University of Michigan, Ann Arbor, MI 48109-1040, USA
| | - Barbara McKenna
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109-0602, USA
| | - Diane Simeone
- Department of Surgery, University of Michigan, Ann Arbor, MI 48109-5331, USA
| | - James Scheiman
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109-0362, USA
- Comprehensive Cancer Center, University of Michigan, Ann Arbor, MI 48109-0944, USA
| | - Mary-Ann Mycek
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109-2099, USA
- Applied Physics Program, University of Michigan, Ann Arbor, MI 48109-1040, USA
- Comprehensive Cancer Center, University of Michigan, Ann Arbor, MI 48109-0944, USA
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OKAGBARE PAULI, MORRIS MICHAELD. Fluorocarbon fiber-optic Raman probe for non-invasive Raman spectroscopy. APPLIED SPECTROSCOPY 2012; 66:728-30. [PMID: 22732546 PMCID: PMC3384561 DOI: 10.1366/12-06592] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We report the development of a novel fiber-optic Raman probe using a graded index fluorocarbon optical fiber. The fluorocarbon fiber has a simple Raman spectrum, a low fluorescence background, and generates a Raman signal that in turbid media serves as an intense reference Raman signal that corrects for albedo. The intensity of the reference signal can easily be varied as needed by scaling the length of the excitation fiber. Additionally, the fluorocarbon probe eliminates the broad silica Raman bands generated in conventional silica-core fiber without the need for filters.
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Ueda Y, Yoshimoto K, Ohmae E, Suzuki T, Yamanaka T, Yamashita D, Ogura H, Teruya C, Nasu H, Ima E, Sakahara H, Oda M, Yamashita Y. Time-resolved optical mammography and its preliminary clinical results. Technol Cancer Res Treat 2012; 10:393-401. [PMID: 21895025 DOI: 10.7785/tcrt.2012.500217] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have been developing an optical mammography prototype consisting of a multi-channel time-resolved spectroscopy system for breast cancer screening. The system utilizes the time-correlated single photon counting method, and the detector modules and the signal processing circuits were custom-made to obtain a high signal to noise ratio and high temperature stability with a high temporal resolution. Pulsed light generated by a Ti: Sapphire laser was irradiated to the breast, and the transmitted light was collected by optical fibers placed on the surface of a hemispherical gantry filled with an optical matching fluid. To reconstruct a 3D image of the breast, we employed a method using a time-resolved photon path distribution based on the assumption that scattering and absorption are independent of each other. We verified the possibility of human breast imaging by using a three-dimensional phantom model, which provides a simulation of human breast cancer, in the gantry. The clinical study was also started in January 2007. In a comparative study with conventional modalities, the breast cancers were detected as regions of optically higher absorption. Moreover, the results suggest that optical mammography is useful in monitoring the effects of chemotherapy.
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Affiliation(s)
- Y Ueda
- Central Research Laboratory, Hamamatsu Photonics K.K., 5000, Hirakuchi, Hamakita-ku, Hamamatsu City, Shizuoka Pref., 434-8601, Japan.
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Okagbare PI, Morris MD. Polymer-capped fiber-optic Raman probe for non-invasive Raman spectroscopy. Analyst 2011; 137:77-81. [PMID: 22059232 DOI: 10.1039/c1an15847c] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Advances in fiber optic probe design are moving Raman spectroscopy into the clinic, although there remain important practical problems. While much effort has been devoted to minimizing Raman and fluorescence background from fibers, less attention has been given to the need to generate reference Raman signals that can correct for variations in tissue albedo, which is important in quantifying changes in tissue composition. To address this shortcoming, we have developed a fiber optic probe that incorporates a fluorinated ethylene-propylene copolymer (FEP) cap at the end of each excitation fiber. Transmission of laser light through the transparent cap generates a 732 cm(-1) Raman band whose intensity scales linearly with the laser power delivered to the tissue of interest. In our first design, the FEP cap functions as a waveguide with only a small insertion loss (~5%). Laser transmission through 1 mm of the polymer is sufficient to generate a usable reference Raman signal. We show the application of the probe to quantitative non-invasive Raman spectroscopy of animal tissues using rat leg phantoms as models. Ex-vivo Raman spectroscopy of excised rat tibia supports the use of the probe for spectroscopy of various tissues. These results provide proof of principle that the Raman probe can be used in multiple spectroscopic applications.
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Affiliation(s)
- Paul I Okagbare
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
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