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Abstract
This article reviews the past and current statuses of time-domain near-infrared spectroscopy (TD-NIRS) and imaging. Although time-domain technology is not yet widely employed due to its drawbacks of being cumbersome, bulky, and very expensive compared to commercial continuous wave (CW) and frequency-domain (FD) fNIRS systems, TD-NIRS has great advantages over CW and FD systems because time-resolved data measured by TD systems contain the richest information about optical properties inside measured objects. This article focuses on reviewing the theoretical background, advanced theories and methods, instruments, and studies on clinical applications for TD-NIRS including some clinical studies which used TD-NIRS systems. Major events in the development of TD-NIRS and imaging are identified and summarized in chronological tables and figures. Finally, prospects for TD-NIRS in the near future are briefly described.
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Hoshi Y, Yamada Y. Overview of diffuse optical tomography and its clinical applications. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:091312. [PMID: 27420810 DOI: 10.1117/1.jbo.21.9.091312] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 06/13/2016] [Indexed: 05/23/2023]
Abstract
Near-infrared diffuse optical tomography (DOT), one of the most sophisticated optical imaging techniques for observations through biological tissue, allows 3-D quantitative imaging of optical properties, which include functional and anatomical information. With DOT, it is expected to be possible to overcome the limitations of conventional near-infrared spectroscopy (NIRS) as well as offering the potential for diagnostic optical imaging. However, DOT has been under development for more than 30 years, and the difficulties in development are attributed to the fact that light is strongly scattered and that diffusive photons are used for the image reconstruction. The DOT algorithm is based on the techniques of inverse problems. The radiative transfer equation accurately describes photon propagation in biological tissue, while, because of its high computation load, the diffusion equation (DE) is often used as the forward model. However, the DE is invalid in low-scattering and/or highly absorbing regions and in the vicinity of light sources. The inverse problem is inherently ill-posed and highly undetermined. Here, we first summarize NIRS and then describe various approaches in the efforts to develop accurate and efficient DOT algorithms and present some examples of clinical applications. Finally, we discuss the future prospects of DOT.
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Affiliation(s)
- Yoko Hoshi
- Hamamatsu University School of Medicine, Department of Biomedical Optics, Institute for Medical Photonics Research, Preeminent Medical Photonics Education and Research Center, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan
| | - Yukio Yamada
- University of Electro-Communications, Brain Science Inspired Life Support Research Center, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
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Abstract
Near-infrared spectroscopy (NIRS) was originally designed for clinical monitoring of tissue oxygenation, and it has also been developed into a useful tool in neuroimaging studies, with the so-called functional NIRS (fNIRS). With NIRS, cerebral activation is detected by measuring the cerebral hemoglobin (Hb), where however, the precise correlation between NIRS signal and neural activity remains to be fully understood. This can in part be attributed to the situation that NIRS signals are inherently subject to contamination by signals arising from extracerebral tissue. In recent years, several approaches have been investigated to distinguish between NIRS signals originating in cerebral tissue and signals originating in extracerebral tissue. Selective measurements of cerebral Hb will enable a further evolution of fNIRS. This chapter is divided into six sections: first a summary of the basic theory of NIRS, NIRS signals arising in the activated areas, correlations between NIRS signals and fMRI signals, correlations between NIRS signals and neural activities, and the influence of a variety of extracerebral tissue on NIRS signals and approaches to this issue are reviewed. Finally, future prospects of fNIRS are described.
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Affiliation(s)
- Y Hoshi
- Institute for Medical Photonics Research, Preeminent Medical Photonics Education & Research Center, Hamamatsu University School of Medicine, Hamamatsu, Japan.
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Martelli F, Del Bianco S, Spinelli L, Cavalieri S, Di Ninni P, Binzoni T, Jelzow A, Macdonald R, Wabnitz H. Optimal estimation reconstruction of the optical properties of a two-layered tissue phantom from time-resolved single-distance measurements. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:115001. [PMID: 26524677 DOI: 10.1117/1.jbo.20.11.115001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 09/25/2015] [Indexed: 05/02/2023]
Abstract
In this work, we have tested the optimal estimation (OE) algorithm for the reconstruction of the optical properties of a two-layered liquid tissue phantom from time-resolved single-distance measurements. The OE allows a priori information, in particular on the range of variation of fit parameters, to be included. The purpose of the present investigations was to compare the performance of OE with the Levenberg–Marquardt method for a geometry and real experimental conditions typically used to reconstruct the optical properties of biological tissues such as muscle and brain. The absorption coefficient of the layers was varied in a range of values typical for biological tissues. The reconstructions performed demonstrate the substantial improvements achievable with the OE provided a priori information is available. We note the extreme reliability, robustness, and accuracy of the retrieved absorption coefficient of the second layer obtained with the OE that was found for up to six fit parameters, with an error in the retrieved values of less than 10%. A priori information on fit parameters and fixed forward model parameters clearly improves robustness and accuracy of the inversion procedure.
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Affiliation(s)
- Fabrizio Martelli
- Università degli Studi di Firenze, Dipartimento di Fisica e Astronomia, Via G. Sansone 1, Sesto Fiorentino 50019, Firenze, Italy
| | - Samuele Del Bianco
- Istituto di Fisica Applicata Nello Carrara del Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, Sesto Fiorentino 50019, Italy
| | - Lorenzo Spinelli
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Piazza Leonardo da Vinci 32, Milano 20133, Italy
| | - Stefano Cavalieri
- Università degli Studi di Firenze, Dipartimento di Fisica e Astronomia, Via G. Sansone 1, Sesto Fiorentino 50019, Firenze, Italy
| | - Paola Di Ninni
- Università degli Studi di Firenze, Dipartimento di Fisica e Astronomia, Via G. Sansone 1, Sesto Fiorentino 50019, Firenze, Italy
| | - Tiziano Binzoni
- University of Geneva, Département de Neurosciences Fondamentales, 1, rue Michel-Servet 1211 Genève 4, SwitzerlandeUniversity Hospital, Département de l'Imagerie et des Sciences de l'Information Médicale, 1, 4 rue Gabrielle-Perret-Gentil, 1211 Geneva 14, S
| | - Alexander Jelzow
- Physikalisch-Technische Bundesanstalt (PTB), Abbestraße 2-12, 10587 Berlin, Germany
| | - Rainer Macdonald
- Physikalisch-Technische Bundesanstalt (PTB), Abbestraße 2-12, 10587 Berlin, Germany
| | - Heidrun Wabnitz
- Physikalisch-Technische Bundesanstalt (PTB), Abbestraße 2-12, 10587 Berlin, Germany
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Effects of Increasing Neuromuscular Electrical Stimulation Current Intensity on Cortical Sensorimotor Network Activation: A Time Domain fNIRS Study. PLoS One 2015; 10:e0131951. [PMID: 26158464 PMCID: PMC4497661 DOI: 10.1371/journal.pone.0131951] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 06/08/2015] [Indexed: 11/29/2022] Open
Abstract
Neuroimaging studies have shown neuromuscular electrical stimulation (NMES)-evoked movements activate regions of the cortical sensorimotor network, including the primary sensorimotor cortex (SMC), premotor cortex (PMC), supplementary motor area (SMA), and secondary somatosensory area (S2), as well as regions of the prefrontal cortex (PFC) known to be involved in pain processing. The aim of this study, on nine healthy subjects, was to compare the cortical network activation profile and pain ratings during NMES of the right forearm wrist extensor muscles at increasing current intensities up to and slightly over the individual maximal tolerated intensity (MTI), and with reference to voluntary (VOL) wrist extension movements. By exploiting the capability of the multi-channel time domain functional near-infrared spectroscopy technique to relate depth information to the photon time-of-flight, the cortical and superficial oxygenated (O2Hb) and deoxygenated (HHb) hemoglobin concentrations were estimated. The O2Hb and HHb maps obtained using the General Linear Model (NIRS-SPM) analysis method, showed that the VOL and NMES-evoked movements significantly increased activation (i.e., increase in O2Hb and corresponding decrease in HHb) in the cortical layer of the contralateral sensorimotor network (SMC, PMC/SMA, and S2). However, the level and area of contralateral sensorimotor network (including PFC) activation was significantly greater for NMES than VOL. Furthermore, there was greater bilateral sensorimotor network activation with the high NMES current intensities which corresponded with increased pain ratings. In conclusion, our findings suggest that greater bilateral sensorimotor network activation profile with high NMES current intensities could be in part attributable to increased attentional/pain processing and to increased bilateral sensorimotor integration in these cortical regions.
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Nakamura M, Jinnai W, Hamano S, Nakamura S, Koyano K, Chiba Y, Kanenishi K, Yasuda S, Ueno M, Miki T, Hata T, Kusaka T. Cerebral blood volume measurement using near-infrared time-resolved spectroscopy and histopathological evaluation after hypoxic-ischemic insult in newborn piglets. Int J Dev Neurosci 2015; 42:1-9. [PMID: 25702525 DOI: 10.1016/j.ijdevneu.2015.02.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 01/28/2015] [Accepted: 02/17/2015] [Indexed: 11/17/2022] Open
Abstract
The aim of this study was to assess the relationship between the cerebral blood volume (CBV) measured by near-infrared time-resolved spectroscopy (TRS) and pathological change of the brain in a hypoxic-ischemic (HI) piglet model. Twenty-one anesthetized newborn piglets, including three sham controls, were studied. An HI event was induced by low inspired oxygen. CBV was measured using TRS (Hamamatsu TRS-10). Data were collected before, during, and 6h after the insult. CBV was calculated as the change from the end of the insult. The piglets were allowed to recover from anesthesia for 6h after the insult. At the age of 5 days, the brains of the piglets were perfusion-fixed, and histologic evaluations of brain tissue were performed. The extent of histopathological damage was graded in 0.5-unit intervals on a 9-step scale. CBV increments were well correlated with histopathological scores, especially at 1 and 3h after resuscitation. Spearman's rank-correlation coefficients at 1, 3, and 6h after resuscitation in the gray matter were 0.9016, 0.9127, and 0.6907, respectively. We conclude that an increased CBV after HI insult indicates more marked histological brain damage. CBV measurement immediately after resuscitation provides a more precise prediction of the histological outcome.
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Affiliation(s)
- Makoto Nakamura
- Department of Pediatrics, Faculty of Medicine, Kagawa University, Kagawa, Japan; Department of Neonatology, National Hospital Organization Okayama Medical Center, Okayama, Japan
| | - Wataru Jinnai
- Maternal Perinatal Center, Faculty of Medicine, Kagawa University, Kagawa, Japan
| | - Satoshi Hamano
- Department of Pediatrics, Faculty of Medicine, Kagawa University, Kagawa, Japan
| | - Shinji Nakamura
- Department of Pediatrics, Faculty of Medicine, Kagawa University, Kagawa, Japan
| | - Kosuke Koyano
- Maternal Perinatal Center, Faculty of Medicine, Kagawa University, Kagawa, Japan
| | - Yoichi Chiba
- Departments of Pathology and Host Defense, Faculty of Medicine, Kagawa University, Kagawa, Japan
| | - Kenji Kanenishi
- Maternal Perinatal Center, Faculty of Medicine, Kagawa University, Kagawa, Japan
| | - Saneyuki Yasuda
- Maternal Perinatal Center, Faculty of Medicine, Kagawa University, Kagawa, Japan
| | - Masaki Ueno
- Departments of Pathology and Host Defense, Faculty of Medicine, Kagawa University, Kagawa, Japan
| | - Takanori Miki
- Departments of Anatomy and Neurobiology, Faculty of Medicine, Kagawa University, Kagawa, Japan
| | - Toshiyuki Hata
- Departments of Perinatology and Gynecology, Faculty of Medicine, Kagawa University, Kagawa, Japan
| | - Takashi Kusaka
- Department of Pediatrics, Faculty of Medicine, Kagawa University, Kagawa, Japan
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Evaluation of cerebral circulation and oxygen metabolism in infants using near-infrared light. Brain Dev 2014; 36:277-83. [PMID: 23800410 DOI: 10.1016/j.braindev.2013.05.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 05/25/2013] [Accepted: 05/29/2013] [Indexed: 11/22/2022]
Abstract
Bedside monitoring of cerebral circulation or oxygen metabolism in infants to appropriately manage circulation and establish the oxygen dose, aiming at improving the neurological prognosis, is needed in general clinical practice. Near-infrared spectroscopy is used for measurements of neonatal cerebral Hb oxygen saturation, cerebral blood volume, cerebral blood flow and cerebral metabolic rate of oxygen. Near-infrared time-resolved spectroscopy is particularly useful for bedside evaluation of cerebral circulation and oxygen metabolism because of its simple measurement procedure. Combined evaluation of cerebral blood volume and cerebral Hb oxygen saturation is expected to contribute to treatment centering on the brain in neonatal medical care.
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Hoshi Y. Towards the next generation of near-infrared spectroscopy. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:4425-39. [PMID: 22006899 DOI: 10.1098/rsta.2011.0262] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Although near-infrared spectroscopy (NIRS) was originally designed for clinical monitoring of tissue oxygenation, it has also been developing into a useful tool for neuroimaging studies (functional NIRS). Over the past 30 years, technology has developed and NIRS has found a wide range of applications. However, the accuracy and reliability of NIRS have not yet been widely accepted, mainly because of the difficulties in selective and quantitative detection of signals arising in cerebral tissue, which subject the use of NIRS to a number of practical restrictions. This review summarizes the strengths and advantages of NIRS over other neuroimaging modalities and demonstrates specific examples. The issues of selective quantitative measurement of cerebral haemoglobin during brain activation are also discussed, together with the problems of applying the methods of functional magnetic resonance imaging data analysis to NIRS data analysis. Finally, near-infrared optical tomography--the next generation of NIRS--is described as a potential technique to overcome the limitations of NIRS.
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Affiliation(s)
- Yoko Hoshi
- Integrated Neuroscience Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
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Virtanen J, Noponen T, Meriläinen P. Comparison of principal and independent component analysis in removing extracerebral interference from near-infrared spectroscopy signals. JOURNAL OF BIOMEDICAL OPTICS 2009; 14:054032. [PMID: 19895134 DOI: 10.1117/1.3253323] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Near-infrared spectroscopy (NIRS) is a method for noninvasive estimation of cerebral hemodynamic changes. Principal component analysis (PCA) and independent component analysis (ICA) can be used for decomposing a set of signals to underlying components. Our objective is to determine whether PCA or ICA is more efficient in identifying and removing scalp blood flow interference from multichannel NIRS signals. Concentration changes of oxygenated (HbO(2)) and deoxygenated (HbR) hemoglobin are measured on the forehead with multichannel NIRS during hyper- and hypocapnia. PCA and ICA are used separately to identify and remove signal contribution from extracerebral tissue, and the resulting estimates of cerebral responses are compared to the expected cerebral responses. Both methods were able to reduce extracerebral contribution to the signals, but PCA typically performs equal to or better than ICA. The improvement in 3-cm signal quality achieved with both methods is comparable to increasing the source-detector separation from 3 to 5 cm. Especially PCA appears to be well suited for use in NIRS applications where the cerebral activation is diffuse, such as monitoring of global cerebral oxygenation and hemodynamics. Performance differences between PCA and ICA could be attributed primarily to different criteria for identifying the surface effect.
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Affiliation(s)
- Jaakko Virtanen
- Helsinki University of Technology, Department of Biomedical Engineering and Computational Science, P.O. Box 3310, FI-02015 TKK, Helsinki, Finland.
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Sayli O, Aksel EB, Akin A. Crosstalk and error analysis of fat layer on continuous wave near-infrared spectroscopy measurements. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:064019. [PMID: 19123665 DOI: 10.1117/1.3028008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Accurate estimation of concentration changes in muscles by continuous wave near-IR spectroscopy for muscle measurements suffers from underestimation and crosstalk problems due to the presence of superficial skin and fat layers. Underestimation error is basically caused by a homogeneous medium assumption in the calculations leading to the partial volume effect. The homogeneous medium assumption and wavelength dependence of mean partial path length in the muscle layer cause the crosstalk. We investigate underestimation errors and crosstalk by Monte Carlo simulations with a three layered (skin-fat-muscle) tissue model for a two-wavelength system where the choice of first wavelength is in the 675- to 775-nm range and the second wavelength is in the 825- to 900-nm range. Means of absolute underestimation errors and crosstalk over the considered wavelength pairs are found to be higher for greater fat thicknesses. Estimation errors of concentration changes for Hb and HbO(2) are calculated to be close for an ischemia type protocol where both Hb and HbO(2) are assumed to have equal magnitude but opposite concentration changes. The minimum estimation errors are found for the 700825- and 725825-nm pairs for this protocol.
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Affiliation(s)
- Omer Sayli
- Bogazici University, Institute of Biomedical Engineering, Bebek, Istanbul, 34342, Turkey
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Hoshi Y. Functional near-infrared spectroscopy: current status and future prospects. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:062106. [PMID: 18163809 DOI: 10.1117/1.2804911] [Citation(s) in RCA: 251] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Near-infrared spectroscopy (NIRS), which was originally designed for clinical monitoring of tissue oxygenation, has been developing into a useful tool for neuroimaging studies (functional near-infrared spectroscopy). This technique, which is completely noninvasive, does not require strict motion restriction and can be used in a daily life environment. It is expected that NIRS will provide a new direction for cognitive neuroscience research, more so than other neuroimaging techniques, although several problems with NIRS remain to be explored. This review demonstrates the strengths and the advantages of NIRS, clarifies the problems, and identifies the limitations of NIRS measurements. Finally, its future prospects are described.
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Affiliation(s)
- Yoko Hoshi
- Tokyo Institute of Psychiatry, Integrated Neuroscience Research Team, 2-1-8 Kamikitazawa, Tokyo 156-8585, Japan.
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Wang A, Nammalavar V, Drezek R. Experimental evaluation of angularly variable fiber geometry for targeting depth-resolved reflectance from layered epithelial tissue phantoms. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:044011. [PMID: 17867815 DOI: 10.1117/1.2769331] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The present study focuses on enhancing the sensitivity and specificity of spectral diagnosis in a stratified architecture that models human cervical epithelia by experimentally demonstrating the efficacy of using angularly variable fiber geometry to achieve the desired layer selection and probing depths. The morphological and biochemical features of epithelial tissue vary in accordance with tissue depths; consequently, the accuracy of spectroscopic diagnosis of epithelial dysplasia may be enhanced by probing the optical properties of this tissue. In the case of cellular dysplasia, layer-specific changes in tissue optical properties may be optimally determined by reflectance spectroscopy when specifically coupled with angularly variable fiber geometry. This study addresses the utility of using such angularly variable fiber geometry for resolving spatially specific spectra of a two-layer epithelial tissue phantom. Spectral sensitivity to the scattering particles embedded in the epithelial phantom layer is shown to significantly improve as the obliquity of the collection fibers increases from 0 to 40 deg. Conversely, the orthogonal fibers are found to be more sensitive to changes in the stromal phantom layer.
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Affiliation(s)
- Adrien Wang
- Rice University, Department of Bioengineering, Houston, Texas 77251-1892, USA
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Spinelli L, Martelli F, Del Bianco S, Pifferi A, Torricelli A, Cubeddu R, Zaccanti G. Absorption and scattering perturbations in homogeneous and layered diffusive media probed by time-resolved reflectance at null source-detector separation. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 74:021919. [PMID: 17025484 DOI: 10.1103/physreve.74.021919] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2006] [Indexed: 05/03/2023]
Abstract
We characterize the capability of time-resolved reflectance measurements at small source-detector separation (less than 5 mm) to localize small inhomogeneities embedded in an otherwise homogeneous or layered diffusive medium. By considering both absorption and scattering inhomogeneities, we demonstrate the improvement of this approach in terms of contrast and spatial resolution, as compared to more typical set-ups involving larger source-detection separations (few centimeters). Simulations are performed exploiting an analytical perturbation approach to diffusion theory and a four-layer heterogeneous time-resolved Monte Carlo code, considering realistic tissue geometries. Exhaustive investigation in the parameters space is reported.
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Affiliation(s)
- Lorenzo Spinelli
- INFM-Dipartimento di Fisica and IFN-CNR, Politecnico di Milano, piazza L. da Vinci 32, I-20133 Milan, Italy
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