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Leartprapun N, Zeng Z, Hajjarian Z, Bossuyt V, Nadkarni SK. Laser speckle rheological microscopy reveals wideband viscoelastic spectra of biological tissues. SCIENCE ADVANCES 2024; 10:eadl1586. [PMID: 38718128 PMCID: PMC11078189 DOI: 10.1126/sciadv.adl1586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 04/04/2024] [Indexed: 05/12/2024]
Abstract
Viscoelastic transformation of tissue drives aberrant cellular functions and is an early biomarker of disease pathogenesis. Tissues scale a range of viscoelastic moduli, from biofluids to bone. Moreover, viscoelastic behavior is governed by the frequency at which tissue is probed, yielding distinct viscous and elastic responses modulated over a wide frequency band. Existing tools do not quantify wideband viscoelastic spectra in tissues, leaving a vast knowledge gap. We present wideband laser speckle rheological microscopy (WB-SHEAR) that reveals elastic and viscous response over sub-megahertz frequencies previously not investigated in tissue. WB-SHEAR uses an optical, noncontact approach to quantify wideband viscoelastic spectra in specimens spanning a range of moduli from low-viscosity fibrin to highly elastic bone. Via laser scanning, micromechanical imaging is enabled to access wideband viscoelastic spectra in heterogeneous tumor specimens with high spatial resolution (25 micrometers). The ability to interrogate the viscoelastic landscape of diverse biospecimens could transform our understanding of mechanobiological processes in various diseases.
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Affiliation(s)
- Nichaluk Leartprapun
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Ziqian Zeng
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Zeinab Hajjarian
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Veerle Bossuyt
- Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Seemantini K. Nadkarni
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
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Leartprapun N, Zeng Z, Hajjarian Z, Bossuyt V, Nadkarni SK. Speckle rheological spectroscopy reveals wideband viscoelastic spectra of biological tissues. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.08.544037. [PMID: 37333220 PMCID: PMC10274797 DOI: 10.1101/2023.06.08.544037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Mechanical transformation of tissue is not merely a symptom but a decisive driver in pathological processes. Comprising intricate network of cells, fibrillar proteins, and interstitial fluid, tissues exhibit distinct solid-(elastic) and liquid-like (viscous) behaviours that span a wide band of frequencies. Yet, characterization of wideband viscoelastic behaviour in whole tissue has not been investigated, leaving a vast knowledge gap in the higher frequency range that is linked to fundamental intracellular processes and microstructural dynamics. Here, we present wideband Speckle rHEologicAl spectRoScopy (SHEARS) to address this need. We demonstrate, for the first time, analysis of frequency-dependent elastic and viscous moduli up to the sub-MHz regime in biomimetic scaffolds and tissue specimens of blood clots, breast tumours, and bone. By capturing previously inaccessible viscoelastic behaviour across the wide frequency spectrum, our approach provides distinct and comprehensive mechanical signatures of tissues that may provide new mechanobiological insights and inform novel disease prognostication.
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Affiliation(s)
- Nichaluk Leartprapun
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114 USA
| | - Ziqian Zeng
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114 USA
| | - Zeinab Hajjarian
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114 USA
| | - Veerle Bossuyt
- Department of Pathology, Massachusetts General Hospital, Boston, MA 02114 USA
| | - Seemantini K. Nadkarni
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114 USA
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The viscoelastic characteristics of in-vitro carotid plaque by Kelvin-Voigt fractional derivative modeling. J Biomech 2022; 141:111210. [DOI: 10.1016/j.jbiomech.2022.111210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 06/10/2022] [Accepted: 06/23/2022] [Indexed: 11/20/2022]
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Shan H, Dai H, Chen X. Monitoring Various Bioactivities at the Molecular, Cellular, Tissue, and Organism Levels via Biological Lasers. SENSORS (BASEL, SWITZERLAND) 2022; 22:3149. [PMID: 35590841 PMCID: PMC9102053 DOI: 10.3390/s22093149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 04/16/2022] [Accepted: 04/18/2022] [Indexed: 06/15/2023]
Abstract
The laser is considered one of the greatest inventions of the 20th century. Biolasers employ high signal-to-noise ratio lasing emission rather than regular fluorescence as the sensing signal, directional out-coupling of lasing and excellent biocompatibility. Meanwhile, biolasers can also be micro-sized or smaller lasers with embedded/integrated biological materials. This article presents the progress in biolasers, focusing on the work done over the past years, including the molecular, cellular, tissue, and organism levels. Furthermore, biolasers have been utilized and explored for broad applications in biosensing, labeling, tracking, bioimaging, and biomedical development due to a number of unique advantages. Finally, we provide the possible directions of biolasers and their applications in the future.
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Affiliation(s)
- Hongrui Shan
- State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China; (H.S.); (H.D.)
| | - Hailang Dai
- State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China; (H.S.); (H.D.)
| | - Xianfeng Chen
- State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China; (H.S.); (H.D.)
- Collaborative Innovation Center of Light Manipulations and Applications, Shandong Normal University, Jinan 250358, China
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Hajjarian Z, Nadkarni SK. Technological perspectives on laser speckle micro-rheology for cancer mechanobiology research. JOURNAL OF BIOMEDICAL OPTICS 2021; 26:JBO-210119-PER. [PMID: 34549559 PMCID: PMC8455299 DOI: 10.1117/1.jbo.26.9.090601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 08/31/2021] [Indexed: 06/13/2023]
Abstract
SIGNIFICANCE The ability to measure the micro-mechanical properties of biological tissues and biomaterials is crucial for numerous fields of cancer research, including tumor mechanobiology, tumor-targeting drug delivery, and therapeutic development. AIM Our goal is to provide a renewed perspective on the mainstream techniques used for micro-mechanical evaluation of biological tissues and biomimetic scaffoldings. We specifically focus on portraying the outlook of laser speckle micro-rheology (LSM), a technology that quantifies the mechanical properties of biomaterials and tissues in a rapid, non-contact manner. APPROACH First, we briefly explain the motivation and significance of evaluating the tissue micro-mechanics in various fields of basic and translational cancer research and introduce the key concepts and quantitative metrics used to explain the mechanical properties of tissue. This is followed by reviewing the general active and passive themes of measuring micro-mechanics. Next, we focus on LSM and elaborate on the theoretical grounds and working principles of this technique. Then, the perspective for measuring the micro-mechanical properties via LSM is outlined. Finally, we draw an overview picture of LSM in cancer mechanobiology research. RESULTS With the continued emergence of new approaches for measuring the mechanical attributes of biological tissues, the field of micro-mechanical imaging is at its boom. As one of these competent innovations, LSM presents a tremendous potential for both technical maturation and prospective applications in cancer biomechanics and mechanobiology research. CONCLUSION By elaborating the current viewpoint of LSM, we expect to accelerate the expansion of this approach to new territories in both technological domains and applied fields. This renewed perspective on LSM may also serve as a road map for other micro-mechanical measurement concepts to be applied for answering mechanobiological questions.
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Affiliation(s)
- Zeinab Hajjarian
- Harvard Medical School, Massachusetts General Hospital, Wellman Center for Photomedicine, Boston, Massachusetts, United States
| | - Seemantini K. Nadkarni
- Harvard Medical School, Massachusetts General Hospital, Wellman Center for Photomedicine, Boston, Massachusetts, United States
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Hajjarian Z, Toussaint JD, Guerrero JL, Nadkarni SK. In-vivo mechanical characterization of coronary atherosclerotic plaques in living swine using intravascular laser speckle imaging. BIOMEDICAL OPTICS EXPRESS 2021; 12:2064-2078. [PMID: 33996217 PMCID: PMC8086462 DOI: 10.1364/boe.418939] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 02/07/2021] [Accepted: 02/09/2021] [Indexed: 05/13/2023]
Abstract
The ability to evaluate the viscoelastic properties of coronary arteries is crucial for identifying mechanically unstable atherosclerotic plaques. Here, we demonstrate for the first time in living swine, the capability of intravascular laser speckle imaging (ILSI) to measure an index of coronary plaque viscoelasticity, τ, using a human coronary to swine xenograft model. Cardiac motion effects are evaluated by comparing the EKG-non-gated τ ¯ N G , and EKG-gated τ ¯ G among different plaque types. Results show that both τ ¯ N G and τ ¯ G are significantly lower in necrotic-core plaques compared with stable lesions. Discrete-point pullback measurements demonstrate the capability of ILSI for rapid mechanical characterization of coronary segments under physiological conditions, in-vivo.
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Affiliation(s)
- Zeinab Hajjarian
- Wellman Center for Photomedicine, Massachusetts General Hospital & Harvard Medical School, Boston, MA 02114, USA
- Authors contributed equally to the manuscript
| | - Jimmy D. Toussaint
- Wellman Center for Photomedicine, Massachusetts General Hospital & Harvard Medical School, Boston, MA 02114, USA
- Authors contributed equally to the manuscript
| | - J. Luis Guerrero
- Surgical Cardiovascular Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Seemantini K. Nadkarni
- Wellman Center for Photomedicine, Massachusetts General Hospital & Harvard Medical School, Boston, MA 02114, USA
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Du S, Chen Z, Xing D. Spectral interferometric depth-resolved photoacoustic viscoelasticity imaging. OPTICS LETTERS 2021; 46:1724-1727. [PMID: 33793528 DOI: 10.1364/ol.415368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 03/06/2021] [Indexed: 06/12/2023]
Abstract
Viscoelasticity is closely related to the physiological characteristics of biological tissues. In this Letter, we propose a novel spectral interferometric depth-resolved photoacoustic viscoelasticity imaging (SID-PAVEI) method, to the best of our knowledge for the first time, which breaks the plight of surface viscoelasticity imaging and achieves an internal visible microscale SID-PAVEI in a noncontact fashion. In this work, we employ a high-sensitive and depth-resolved spectral domain low coherence interferometry (SDLCI) to remotely track photoacoustic-induced strain response of absorbers in situ. By decoupling the phase and amplitude of the photoacoustic-encoded spectral interference signal, the SID-PAVEI and scattering structure imaging (SSI) can be obtained simultaneously. Depth-resolved performance of the SID-PAVEI and the SSI in one scan were demonstrated by imaging biological tissues. The method opens new perspectives for three-dimensional microscale viscoelasticity imaging and provides a great potential in multi-parametric characterizing pathological information.
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Youssef D, Hassab-Elnaby S, El-Ghandoor H. Nanoscale quantitative surface roughness measurement of articular cartilage using second-order statistical-based biospeckle. PLoS One 2021; 16:e0246395. [PMID: 33513197 PMCID: PMC7845957 DOI: 10.1371/journal.pone.0246395] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Accepted: 01/17/2021] [Indexed: 11/19/2022] Open
Abstract
Quantitative measurement of nanoscale surface roughness of articular cartilage tissue is significant to assess the surface topography for early treatment of osteoarthritis, the most common joint disease worldwide. Since it was not established by clinical diagnostic tools, the current studies have been suggesting the use of alternative diagnostic tools using pre-clinical methods. This study aims to measure the nanoscale surface roughness of articular cartilage tissue utilizing biospeckle which is used as a non-destructive and non-contact optical imaging technique. An experimental setup was implemented to capture biospeckle images from twelve cross-section areas of articular cartilage tissue gathered from bovine knee joints at 632 nm wavelength laser radiation. Then, to analyze the biospeckle image, a second-order statistical-based method was proposed through the combination of 308 highly correlated statistical features extracted from implemented gray-level co-occurrence matrices by employing principal component analysis. The result indicated that the measurement of the nanoscale surface roughness based on the first principal component only is able to provide accurate and precise quantitative measurement of early signs of articular cartilage degeneration up to 2500 nm.
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Affiliation(s)
- Doaa Youssef
- Department of Engineering Applications of Laser, National Institute of Laser Enhanced Science, Cairo University, Giza, Egypt
- * E-mail:
| | - Salah Hassab-Elnaby
- Department of Engineering Applications of Laser, National Institute of Laser Enhanced Science, Cairo University, Giza, Egypt
| | - Hatem El-Ghandoor
- Faculty of Science, Department of Physics, Ain Shams University, Cairo, Egypt
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Hajjarian Z, Nadkarni SK. Tutorial on laser speckle rheology: technology, applications, and opportunities. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:1-19. [PMID: 32358928 PMCID: PMC7195443 DOI: 10.1117/1.jbo.25.5.050801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 04/10/2020] [Indexed: 05/27/2023]
Abstract
SIGNIFICANCE The onset of several diseases is frequently marked with anomalous mechanical alteration of the affected tissue at the intersection of cells and their microenvironment. Therefore, mapping the micromechanical attributes of the tissues could enhance our understanding of the etiology of human disease, improve the diagnosis, and help stratify therapies that target these mechanical aberrations. AIM We review the tremendous opportunities offered through using optics for imaging the micromechanical properties, at length scales inaccessible to other modalities, in both basic research and clinical medicine. We specifically focus on laser speckle rheology (LSR), a technology that quantifies the mechanical properties of tissues in a rapid, noncontact manner. APPROACH In LSR, the shear viscoelastic modulus is measured from the time-variant speckle intensity fluctuations reflected off the tissue. The LSR technology is engineered and configured into several embodiments, including bench-top optical systems, endoscopes for minimally invasive procedures, portable point-of-care devices, and microscopes. RESULTS These technological nuances have primed the LSR for widespread applications in diagnosis and therapeutic monitoring, as demonstrated here, in cardiovascular disease, coagulation disorders, and tumor malignancies. CONCLUSION The fast-paced technological advancements, elaborated here, position the LSR as a competent candidate for many more exciting opportunities in basic research and medicine.
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Affiliation(s)
- Zeinab Hajjarian
- Massachusetts General Hospital, Harvard Medical School, Wellman Center for Photomedicine, Boston, Massachusetts, United States
| | - Seemantini K. Nadkarni
- Massachusetts General Hospital, Harvard Medical School, Wellman Center for Photomedicine, Boston, Massachusetts, United States
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Wang P, Chen Z, Xing D. Multi-parameter characterization of atherosclerotic plaques based on optical coherence tomography, photoacoustic and viscoelasticity imaging. OPTICS EXPRESS 2020; 28:13761-13774. [PMID: 32403844 DOI: 10.1364/oe.390874] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 04/11/2020] [Indexed: 06/11/2023]
Abstract
Detection of atherosclerotic plaque vulnerability is the critical step in prevention of acute coronary events. Fibrous cap thickness, lipid core size, and inflammation extent are three key parameters for assessing plaque vulnerability. Here, we report on multimodality imaging of mice aortic plaques using a system that integrates optical coherence tomography (OCT), photoacoustic imaging (PAI), and photoacoustic viscoelasticity imaging (PAVEI). The thickness of fibrous cap is accurately evaluated by OCT, and PAI helps to determine the distribution and size of lipid core. The mechanical properties of plaques are closely related to the plaque compositions and the content and distribution of macrophages, while PAVEI can characterize the plaque viscoelasticity through the phase delay of photoacoustic signal. Experimental results demonstrate that the OCT-PAI-PAVEI system can comprehensively characterize the three traits of atherosclerotic plaques, thereby identifying high-risk lesions.
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B A, Rao S, Pandya HJ. Engineering approaches for characterizing soft tissue mechanical properties: A review. Clin Biomech (Bristol, Avon) 2019; 69:127-140. [PMID: 31344655 DOI: 10.1016/j.clinbiomech.2019.07.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 03/14/2019] [Accepted: 07/15/2019] [Indexed: 02/07/2023]
Abstract
From cancer diagnosis to detailed characterization of arterial wall biomechanics, the elastic property of tissues is widely studied as an early sign of disease onset. The fibrous structural features of tissues are a direct measure of its health and functionality. Alterations in the structural features of tissues are often manifested as local stiffening and are early signs for diagnosing a disease. These elastic properties are measured ex vivo in conventional mechanical testing regimes, however, the heterogeneous microstructure of tissues can be accurately resolved over relatively smaller length scales with enhanced spatial resolution using techniques such as micro-indentation, microelectromechanical (MEMS) based cantilever sensors and optical catheters which also facilitate in vivo assessment of mechanical properties. In this review, we describe several probing strategies (qualitative and quantitative) based on the spatial scale of mechanical assessment and also discuss the potential use of machine learning techniques to compute the mechanical properties of soft tissues. This work details state of the art advancement in probing strategies, associated challenges toward quantitative characterization of tissue biomechanics both from an engineering and clinical standpoint.
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Affiliation(s)
- Alekya B
- Biomedical and Electronic (10(-6)-10(-9)) Engineering Systems Laboratory, Department of Electronic Systems Engineering, Indian Institute of Science, Bangalore 12, India
| | - Sanjay Rao
- Department of Pediatric Surgery, Mazumdar Shaw Multispecialty Hospital, Narayana Health, Bangalore 99, India
| | - Hardik J Pandya
- Biomedical and Electronic (10(-6)-10(-9)) Engineering Systems Laboratory, Department of Electronic Systems Engineering, Indian Institute of Science, Bangalore 12, India.
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Yokoi N, Aizu Y, Uozumi J. Analysis of blood coagulation process based on fractality and dynamic characteristic of laser speckle pattern. JOURNAL OF BIOMEDICAL OPTICS 2018; 24:1-7. [PMID: 30569670 PMCID: PMC6975187 DOI: 10.1117/1.jbo.24.3.031018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 11/28/2018] [Indexed: 06/09/2023]
Abstract
The reflection and transmission of coherent light from a biological system can yield information about its condition. In the case of blood exposed to the air, there is a change in the properties of the speckle patterns observed in the coagulation process. This can be studied by means of the rate of temporal variation, the contrast, and also the fractality of patterns. The fractality of the speckle pattern can be investigated by a fractal dimension, which can quantify a level of the complexity of platelet aggregation structure and a fibrin network formed in the process of blood coagulation. In addition, dynamic characteristics of a movement in blood also contain information on the progress of the coagulation process. Fractality and dynamic characteristics are investigated simultaneously for speckle patterns observed in the coagulation process of stored horse blood. Experimental results show the feasibility of the proposed method for detecting hemolysis and formation of platelet aggregation structure and the fibrin network during the coagulation process.
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Affiliation(s)
- Naomichi Yokoi
- National Institute of Technology, Asahikawa College, Department of Mechanical Systems Engineering, Asahikawa, Japan
| | - Yoshihisa Aizu
- Muroran Institute of Technology, College of Design and Manufacturing Technology, Muroran, Japan
| | - Jun Uozumi
- Hokkai-Gakuen University, Department of Electronics and Information Engineering, Sapporo, Japan
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Chen X, Wang Y, Lu J, Li P. Simultaneous viscosity and elasticity measurement using laser speckle contrast imaging. OPTICS LETTERS 2018; 43:1582-1585. [PMID: 29601035 DOI: 10.1364/ol.43.001582] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 03/03/2018] [Indexed: 06/08/2023]
Abstract
Viscosity and elasticity are closely related to the physiological characteristics of biological tissues. This Letter reports a simultaneous quantitative measurement of these parameters realized with the laser speckle contrast imaging method. The propagation of a Rayleigh wave induced by an acoustic speaker is traced, and the frequency-dependent velocity dispersion is extracted with the frequency-wavenumber spectrum analysis method. The viscosity and elasticity moduli of oil-in-gelatin tissue-mimicking phantoms are calculated by fitting the dispersion curves to the Voigt model. The method is validated by comparing it with the results obtained by using a conventional mechanical rheometer.
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Vitomir L, Sprakel J, van der Gucht J. Spatial blurring in laser speckle imaging in inhomogeneous turbid media. Sci Rep 2017; 7:16879. [PMID: 29203904 PMCID: PMC5715131 DOI: 10.1038/s41598-017-17010-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 11/20/2017] [Indexed: 11/08/2022] Open
Abstract
Laser speckle imaging (LSI) has developed into a versatile tool to image dynamical processes in turbid media, such as subcutaneous blood perfusion and heterogeneous dynamics in soft materials. Spatially resolved information about local dynamics is obtained by measuring time-dependent correlation functions of multiply scattered light. Due to the diffusive nature of photons in highly scattering media, the measured signal is a convolution of the local dynamics in the material and the spatial distribution of photons. This spatial averaging inevitably leads to a loss of resolution, which must be taken into account for a correct interpretation of LSI measurements. In this paper we derive analytical expressions to quantify the effects of spatial blurring in backscatter LSI for materials with heterogeneous dynamics. Using the diffusion approximation, we calculate the photon density distribution for a semi-infinite material, and we predict the effect of dynamic heterogeneity on the measured correlation function. We verify our theoretical expressions using random walk simulations. Our results show that LSI measurements in dynamically heterogeneous materials should be interpreted with caution, especially when only a single wavelength and correlation time are used to obtain the dynamical map.
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Affiliation(s)
- Luka Vitomir
- Wageningen University and Research Center, Department of Physical Chemistry and Soft Matter, Wageningen, 6708, WE, Netherlands
| | - Joris Sprakel
- Wageningen University and Research Center, Department of Physical Chemistry and Soft Matter, Wageningen, 6708, WE, Netherlands
| | - Jasper van der Gucht
- Wageningen University and Research Center, Department of Physical Chemistry and Soft Matter, Wageningen, 6708, WE, Netherlands.
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A multiphysics approach for modeling early atherosclerosis. Biomech Model Mechanobiol 2017; 17:617-644. [PMID: 29159532 DOI: 10.1007/s10237-017-0982-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 11/04/2017] [Indexed: 01/03/2023]
Abstract
This work is devoted to the development of a mathematical model of the early stages of atherosclerosis incorporating processes of all time scales of the disease and to show their interactions. The cardiovascular mechanics is modeled by a fluid-structure interaction approach coupling a non-Newtonian fluid to a hyperelastic solid undergoing anisotropic growth and a change of its constitutive equation. Additionally, the transport of low-density lipoproteins and its penetration through the endothelium is considered by a coupled set of advection-diffusion-reaction equations. Thereby, the permeability of the endothelium is wall-shear stress modulated resulting in a locally varying accumulation of foam cells triggering a novel growth and remodeling formulation. The model is calibrated and applied to an murine-specific case study, and a qualitative validation of the computational results is performed. The model is utilized to further investigate the influence of the pulsatile blood flow and the compliance of the artery wall to the atherosclerotic process. The computational results imply that the pulsatile blood flow is crucial, whereas the compliance of the aorta has only a minor influence on atherosclerosis. Further, it is shown that the novel model is capable to produce a narrowing of the vessel lumen inducing an adaption of the endothelial permeability pattern.
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Tshikudi DM, Tripathi MM, Hajjarian Z, Van Cott EM, Nadkarni SK. Optical sensing of anticoagulation status: Towards point-of-care coagulation testing. PLoS One 2017; 12:e0182491. [PMID: 28771571 PMCID: PMC5542647 DOI: 10.1371/journal.pone.0182491] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 07/19/2017] [Indexed: 11/18/2022] Open
Abstract
Anticoagulant overdose is associated with major bleeding complications. Rapid coagulation sensing may ensure safe and accurate anticoagulant dosing and reduce bleeding risk. Here, we report the novel use of Laser Speckle Rheology (LSR) for measuring anticoagulation and haemodilution status in whole blood. In the LSR approach, blood from 12 patients and 4 swine was placed in disposable cartridges and time-varying intensity fluctuations of laser speckle patterns were measured to quantify the viscoelastic modulus during clotting. Coagulation parameters, mainly clotting time, clot progression rate (α-angle) and maximum clot stiffness (MA) were derived from the clot viscoelasticity trace and compared with standard Thromboelastography (TEG). To demonstrate the capability for anticoagulation sensing in patients, blood samples from 12 patients treated with warfarin anticoagulant were analyzed. LSR clotting time correlated with prothrombin and activated partial thromboplastin time (r = 0.57-0.77, p<0.04) and all LSR parameters demonstrated good correlation with TEG (r = 0.61-0.87, p<0.04). To further evaluate the dose-dependent sensitivity of LSR parameters, swine blood was spiked with varying concentrations of heparin, argatroban and rivaroxaban or serially diluted with saline. We observed that anticoagulant treatments prolonged LSR clotting time in a dose-dependent manner that correlated closely with TEG (r = 0.99, p<0.01). LSR angle was unaltered by anticoagulation whereas TEG angle presented dose-dependent diminution likely linked to the mechanical manipulation of the clot. In both LSR and TEG, MA was largely unaffected by anticoagulation, and LSR presented a higher sensitivity to increased haemodilution in comparison to TEG (p<0.01). Our results establish that LSR rapidly and accurately measures the response of various anticoagulants, opening the opportunity for routine anticoagulation monitoring at the point-of-care or for patient self-testing.
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Affiliation(s)
- Diane M. Tshikudi
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Markandey M. Tripathi
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Zeinab Hajjarian
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Elizabeth M. Van Cott
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Seemantini K. Nadkarni
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States of America
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Wang J, Hosoda M, Tshikudi DM, Hajjarian Z, Nadkarni SK. Intraluminal laser speckle rheology using an omni-directional viewing catheter. BIOMEDICAL OPTICS EXPRESS 2017; 8:137-150. [PMID: 28101407 PMCID: PMC5231287 DOI: 10.1364/boe.8.000137] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 12/04/2016] [Accepted: 12/05/2016] [Indexed: 05/27/2023]
Abstract
A number of disease conditions in luminal organs are associated with alterations in tissue mechanical properties. Here, we report a new omni-directional viewing Laser Speckle Rheology (LSR) catheter for mapping the mechanical properties of luminal organs without the need for rotational motion. The LSR catheter incorporates multiple illumination fibers, an optical fiber bundle and a multi-faceted mirror to permit omni-directional viewing of the luminal wall. By retracting the catheter using a motor-drive assembly, cylindrical maps of tissue mechanical properties are reconstructed. Evaluation conducted in a test phantom with circumferentially-varying mechanical properties demonstrates the capability of the LSR catheter for the accurate mechanical assessment of luminal organs.
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Affiliation(s)
- Jing Wang
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, MA 02114, USA
- Authors contributed equally to this work
| | - Masaki Hosoda
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, MA 02114, USA
- Healthcare Optics Research Laboratory, Canon U.S.A., Inc., Cambridge, MA 02139, USA
- Authors contributed equally to this work
| | - Diane M. Tshikudi
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, MA 02114, USA
| | - Zeinab Hajjarian
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, MA 02114, USA
| | - Seemantini K. Nadkarni
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, MA 02114, USA
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18
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Laser Speckle Rheology for evaluating the viscoelastic properties of hydrogel scaffolds. Sci Rep 2016; 6:37949. [PMID: 27905494 PMCID: PMC5131361 DOI: 10.1038/srep37949] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 11/02/2016] [Indexed: 11/08/2022] Open
Abstract
Natural and synthetic hydrogel scaffolds exhibit distinct viscoelastic properties at various length scales and deformation rates. Laser Speckle Rheology (LSR) offers a novel, non-contact optical approach for evaluating the frequency-dependent viscoelastic properties of hydrogels. In LSR, a coherent laser beam illuminates the specimen and a high-speed camera acquires the time-varying speckle images. Cross-correlation analysis of frames returns the speckle intensity autocorrelation function, g2(t), from which the frequency-dependent viscoelastic modulus, G*(ω), is deduced. Here, we establish the capability of LSR for evaluating the viscoelastic properties of hydrogels over a large range of moduli, using conventional mechanical rheometry and atomic force microscopy (AFM)-based indentation as reference-standards. Results demonstrate a strong correlation between |G*(ω)| values measured by LSR and mechanical rheometry (r = 0.95, p < 10−9), and z-test analysis reports that moduli values measured by the two methods are identical (p > 0.08) over a large range (47 Pa – 36 kPa). In addition, |G*(ω)| values measured by LSR correlate well with indentation moduli, E, reported by AFM (r = 0.92, p < 10−7). Further, spatially-resolved moduli measurements in micro-patterned substrates demonstrate that LSR combines the strengths of conventional rheology and micro-indentation in assessing hydrogel viscoelastic properties at multiple frequencies and small length-scales.
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19
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Gubarkova EV, Dudenkova VV, Feldchtein FI, Timofeeva LB, Kiseleva EB, Kuznetsov SS, Shakhov BE, Moiseev AA, Gelikonov VM, Gelikonov GV, Vitkin A, Gladkova ND. Multi-modal optical imaging characterization of atherosclerotic plaques. JOURNAL OF BIOPHOTONICS 2016; 9:1009-1020. [PMID: 26604168 DOI: 10.1002/jbio.201500223] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 11/01/2015] [Accepted: 11/04/2015] [Indexed: 05/08/2023]
Abstract
We combined cross-polarization optical coherence tomography (CP OCT) and non-linear microscopy based on second harmonic generation (SHG) and two-photon-excited fluorescence (2PEF) to assess collagen and elastin fibers and other vascular structures in the development of atherosclerosis, including identification of vulnerable plaques, which remains an important clinical problem and imaging application. CP OCT's ability to visualize tissue birefringence and cross-scattering adds new information about the microstructure and composition of the plaque. However its interpretation can be ambiguous, because backscattering contrast may have a similar appearance to the birefringence related fringes. Our results represent a step towards minimally invasive characterization and monitoring of different stages of atherosclerosis, including vulnerable plaques. CP OCT image of intimal thickening in the human coronary artery. The dark stripe in the cross-polarization channel (arrow) is a polarization fringe related to the phase retardation between two eigen polarization states. It is histologically located in the area of the lipid pool, however this stripe is a polarization artifact, rather than direct visualization of the lipid pool.
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Affiliation(s)
- Ekaterina V Gubarkova
- Nizhny Novgorod State Medical Academy, 603005 Minin and Pozharsky Sq., 10/1, Nizhny Novgorod, Russia.
| | - Varvara V Dudenkova
- Nizhny Novgorod State Medical Academy, 603005 Minin and Pozharsky Sq., 10/1, Nizhny Novgorod, Russia
- N.I. Lobachevsky State University of Nizhny Novgorod, 603950, 23 Gagarin St., Nizhny Novgorod, Russia
| | - Felix I Feldchtein
- Nizhny Novgorod State Medical Academy, 603005 Minin and Pozharsky Sq., 10/1, Nizhny Novgorod, Russia
| | - Lidia B Timofeeva
- Nizhny Novgorod State Medical Academy, 603005 Minin and Pozharsky Sq., 10/1, Nizhny Novgorod, Russia
| | - Elena B Kiseleva
- Nizhny Novgorod State Medical Academy, 603005 Minin and Pozharsky Sq., 10/1, Nizhny Novgorod, Russia
| | - Sergei S Kuznetsov
- Nizhny Novgorod State Medical Academy, 603005 Minin and Pozharsky Sq., 10/1, Nizhny Novgorod, Russia
| | - Boris E Shakhov
- Nizhny Novgorod State Medical Academy, 603005 Minin and Pozharsky Sq., 10/1, Nizhny Novgorod, Russia
| | - Alexander A Moiseev
- Institute of Applied Physics RAS, 603950 Ulyanov St., 46, Nizhny Novgorod, Russia
| | - Valentin M Gelikonov
- Institute of Applied Physics RAS, 603950 Ulyanov St., 46, Nizhny Novgorod, Russia
| | - Gregory V Gelikonov
- Institute of Applied Physics RAS, 603950 Ulyanov St., 46, Nizhny Novgorod, Russia
| | - Alex Vitkin
- Nizhny Novgorod State Medical Academy, 603005 Minin and Pozharsky Sq., 10/1, Nizhny Novgorod, Russia
- Departments of Medical Biophysics and Radiation Oncology, University of Toronto, Ontario, M5G 2M9, Canada
- Ontario Cancer Institute, University Health Network, Toronto, Ontario, M5G 2M9, Canada
| | - Natalia D Gladkova
- Nizhny Novgorod State Medical Academy, 603005 Minin and Pozharsky Sq., 10/1, Nizhny Novgorod, Russia
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20
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Basak K, Dey G, Mahadevappa M, Mandal M, Sheet D, Dutta PK. Learning of speckle statistics for in vivo and noninvasive characterization of cutaneous wound regions using laser speckle contrast imaging. Microvasc Res 2016; 107:6-16. [PMID: 27131831 DOI: 10.1016/j.mvr.2016.04.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 04/04/2016] [Accepted: 04/24/2016] [Indexed: 11/17/2022]
Abstract
Laser speckle contrast imaging (LSCI) provides a noninvasive and cost effective solution for in vivo monitoring of blood flow. So far, most of the researches consider changes in speckle pattern (i.e. correlation time of speckle intensity fluctuation), account for relative change in blood flow during abnormal conditions. This paper introduces an application of LSCI for monitoring wound progression and characterization of cutaneous wound regions on mice model. Speckle images are captured on a tumor wound region at mice leg in periodic interval. Initially, raw speckle images are converted to their corresponding contrast images. Functional characterization begins with first segmenting the affected area using k-means clustering, taking wavelet energies in a local region as feature set. In the next stage, different regions in wound bed are clustered based on progressive and non-progressive nature of tissue properties. Changes in contrast due to heterogeneity in tissue structure and functionality are modeled using LSCI speckle statistics. Final characterization is achieved through supervised learning of these speckle statistics using support vector machine. On cross evaluation with mice model experiment, the proposed approach classifies the progressive and non-progressive wound regions with an average sensitivity of 96.18%, 97.62% and average specificity of 97.24%, 96.42% respectively. The clinical information yield with this approach is validated with the conventional immunohistochemistry result of wound to justify the ability of LSCI for in vivo, noninvasive and periodic assessment of wounds.
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Affiliation(s)
- Kausik Basak
- Electrical and Electronics Engineering Department, Mahindra Ecole Centrale, Hyderabad 500043, India.
| | - Goutam Dey
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Manjunatha Mahadevappa
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Mahitosh Mandal
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Debdoot Sheet
- Department of Electrical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Pranab Kumar Dutta
- Department of Electrical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
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21
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Wu M, Fw van der Steen A, Regar E, van Soest G. Emerging Technology Update Intravascular Photoacoustic Imaging of Vulnerable Atherosclerotic Plaque. Interv Cardiol 2016; 11:120-123. [PMID: 29588718 DOI: 10.15420/icr.2016:13:3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The identification of vulnerable atherosclerotic plaques in the coronary arteries is emerging as an important tool for guiding atherosclerosis diagnosis and interventions. Assessment of plaque vulnerability requires knowledge of both the structure and composition of the plaque. Intravascular photoacoustic (IVPA) imaging is able to show the morphology and composition of atherosclerotic plaque. With imminent improvements in IVPA imaging, it is becoming possible to assess human coronary artery disease in vivo. Although some challenges remain, IVPA imaging is on its way to being a powerful tool for visualising coronary atherosclerotic features that have been specifically associated with plaque vulnerability and clinical syndromes, and thus such imaging might become valuable for clinical risk assessment in the catheterisation laboratory.
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Affiliation(s)
- Min Wu
- Department of Biomedical Engineering, Thorax Centre, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Antonius Fw van der Steen
- Department of Biomedical Engineering, Thorax Centre, Erasmus Medical Center, Rotterdam, The Netherlands.,Interuniversity Cardiology Institute of The Netherlands, Netherlands Heart Institute, Utrecht, The Netherlands.,Department of Imaging Science and Technology, Delft University of Technology, Delft, The Netherlands.,Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Evelyn Regar
- Department of interventional cardiology, Thorax Center, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Gijs van Soest
- Department of Biomedical Engineering, Thorax Centre, Erasmus Medical Center, Rotterdam, The Netherlands
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22
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Hajjarian Z, Tripathi MM, Nadkarni SK. Optical Thromboelastography to evaluate whole blood coagulation. JOURNAL OF BIOPHOTONICS 2015; 8:372-81. [PMID: 24700701 PMCID: PMC4605542 DOI: 10.1002/jbio.201300197] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 03/07/2014] [Accepted: 03/15/2014] [Indexed: 05/12/2023]
Abstract
Measurement of blood viscoelasticity during clotting provides a direct metric of haemostatic conditions. Therefore, technologies that quantify blood viscoelasticity at the point-of-care are invaluable for diagnosing coagulopathies. We present a new approach, Optical Thromboelastography (OTEG) that measures the viscoelastic properties of coagulating blood by evaluating temporal laser speckle fluctuations, reflected from a few blood drops. During coagulation, platelet-fibrin clot formation restricts the mean square displacements (MSD) of scatterers and decelerates speckle fluctuations. Cross-correlation analysis of speckle frames provides the speckle intensity temporal autocorrelation, g2 (t), from which MSD is deduced and the viscoelastic modulus of blood is estimated. Our results demonstrate a close correspondence between blood viscoelasticity evaluated by OTEG and mechanical rheometry. Spatio-temporal speckle analyses yield 2-dimensional maps of clot viscoelasticity, enabling the identification of micro-clot formation at distinct rates in normal and coagulopathic specimens. These findings confirm the unique capability of OTEG for the rapid evaluation of patients' coagulation status and highlight the potential for point-of-care use.
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Affiliation(s)
- Zeinab Hajjarian
- Wellman Center For Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Markandey M Tripathi
- Wellman Center For Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Seemantini K Nadkarni
- Wellman Center For Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
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23
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Wang S, Larin KV. Optical coherence elastography for tissue characterization: a review. JOURNAL OF BIOPHOTONICS 2015; 8:279-302. [PMID: 25412100 PMCID: PMC4410708 DOI: 10.1002/jbio.201400108] [Citation(s) in RCA: 134] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 10/24/2014] [Accepted: 10/24/2014] [Indexed: 05/05/2023]
Abstract
Optical coherence elastography (OCE) represents the frontier of optical elasticity imaging techniques and focuses on the micro-scale assessment of tissue biomechanics in 3D that is hard to achieve with traditional elastographic methods. Benefit from the advancement of optical coherence tomography, and driven by the increasing requirements in nondestructive biomechanical characterization, this emerging technique recently has experienced a rapid development. In this paper, we start with the description of the mechanical contrast that has been employed by OCE and review the state-of-the-art techniques based on the reported applications and discuss the current technical challenges, emphasizing the unique role of OCE in tissue mechanical characterization. The position of OCE among other elastography techniques.
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Affiliation(s)
- Shang Wang
- Department of Biomedical Engineering, University of Houston, 3605 Cullen Blvd., Houston, Texas, 77204-5060, USA; Department of Molecular Physiology and Biophysics, Baylor College of medicine, one Baylor Plaza, Houston, Texas, 77030, USA
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24
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Wang S, Larin KV. Optical coherence elastography for tissue characterization: a review. JOURNAL OF BIOPHOTONICS 2015. [PMID: 25412100 DOI: 10.1002/jbio.v8.4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Optical coherence elastography (OCE) represents the frontier of optical elasticity imaging techniques and focuses on the micro-scale assessment of tissue biomechanics in 3D that is hard to achieve with traditional elastographic methods. Benefit from the advancement of optical coherence tomography, and driven by the increasing requirements in nondestructive biomechanical characterization, this emerging technique recently has experienced a rapid development. In this paper, we start with the description of the mechanical contrast that has been employed by OCE and review the state-of-the-art techniques based on the reported applications and discuss the current technical challenges, emphasizing the unique role of OCE in tissue mechanical characterization. The position of OCE among other elastography techniques.
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Affiliation(s)
- Shang Wang
- Department of Biomedical Engineering, University of Houston, 3605 Cullen Blvd., Houston, Texas, 77204-5060, USA; Department of Molecular Physiology and Biophysics, Baylor College of medicine, one Baylor Plaza, Houston, Texas, 77030, USA
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25
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Hajjarian Z, Nadkarni SK. Estimation of particle size variations for laser speckle rheology of materials. OPTICS LETTERS 2015; 40:764-7. [PMID: 25723427 PMCID: PMC4605544 DOI: 10.1364/ol.40.000764] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Laser speckle rheology (LSR) is an optical technique for assessing the viscoelastic properties of materials with several industrial, biological, and medical applications. In LSR, the viscoelastic modulus, G*(ω), of a material is quantified by analyzing the temporal fluctuations of speckle patterns. However, the size of scattering particles within the material also influences the rate of speckle fluctuations, independent of sample mechanical properties, and complicates the accurate estimation of G*(ω). Here, we demonstrate that the average particle size may be retrieved from the azimuth-angle dependence of time-averaged speckle intensities, permitting the accurate quantification of the viscoelastic moduli of materials with unknown particle size distribution using LSR.
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Affiliation(s)
- Zeinab Hajjarian
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, 40 Blossom Street, BAR-7, Boston, Massachusetts 02114, USA
| | - Seemantini K. Nadkarni
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, 40 Blossom Street, BAR-7, Boston, Massachusetts 02114, USA
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26
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Brezinski ME. Practical Challenges of Current Video Rate OCT Elastography: Accounting for Dynamic and Static Tissue Properties. JOURNAL OF LASERS, OPTICS & PHOTONICS 2014; 1:112. [PMID: 29286052 PMCID: PMC5743221 DOI: 10.4172/2469-410x.1000112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Optical coherence tomography (OCT) elastography (OCTE) has the potential to be an important diagnostic tool for pathologies including coronary artery disease, osteoarthritis, malignancies, and even dental caries. Many groups have performed OCTE, including our own, using a wide range of approaches. However, we will demonstrate current OCTE approaches are not scalable to real-time, in vivo imaging. As will be discussed, among the most important reasons is current designs focus on the system and not the target. Specifically, tissue dynamic responses are not accounted, with examples being the tissue strain response time, preload variability, and conditioning variability. Tissue dynamic responses, and to a lesser degree static tissue properties, prevent accurate video rate modulus assessments for current embodiments. Accounting for them is the focus of this paper. A top-down approach will be presented to overcome these challenges to real time in vivo tissue characterization. Discussed first is an example clinical scenario where OTCE would be of substantial relevance, the prevention of acute myocardial infarction or heart attacks. Then the principles behind OCTE are examined. Next, constrains on in vivo application of current OCTE are evaluated, focusing on dynamic tissue responses. An example is the tissue strain response, where it takes about 20 msec after a stress is applied to reach plateau. This response delay is not an issue at slow acquisition rates, as most current OCTE approaches are preformed, but it is for video rate OCTE. Since at video rate each frame is only 30 msec, for essentially all current approaches this means the strain for a given stress is changing constantly during the B-scan. Therefore the modulus can't be accurately assessed. This serious issue is an even greater problem for pulsed techniques as it means the strain/modulus for a given stress (at a location) is unpredictably changing over a B-scan. The paper concludes by introducing a novel video rate approach to overcome these challenges.
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Affiliation(s)
- Mark E Brezinski
- Center for Optics and Modern Physics, Brigham and Women’s Hospital, 75 Francis Street, Boston, M.A. 02115, USA
- Harvard Medical School, 25 Shattuck Street, Boston, M.A. 02115, USA
- Department of Electrical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, M.A. 02139, USA
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27
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Kennedy BF, McLaughlin RA, Kennedy KM, Chin L, Curatolo A, Tien A, Latham B, Saunders CM, Sampson DD. Optical coherence micro-elastography: mechanical-contrast imaging of tissue microstructure. BIOMEDICAL OPTICS EXPRESS 2014; 5:2113-24. [PMID: 25071952 PMCID: PMC4102352 DOI: 10.1364/boe.5.002113] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 05/28/2014] [Accepted: 05/30/2014] [Indexed: 05/18/2023]
Abstract
We present optical coherence micro-elastography, an improved form of compression optical coherence elastography. We demonstrate the capacity of this technique to produce en face images, closely corresponding with histology, that reveal micro-scale mechanical contrast in human breast and lymph node tissues. We use phase-sensitive, three-dimensional optical coherence tomography (OCT) to probe the nanometer-to-micrometer-scale axial displacements in tissues induced by compressive loading. Optical coherence micro-elastography incorporates common-path interferometry, weighted averaging of the complex OCT signal and weighted least-squares regression. Using three-dimensional phase unwrapping, we have increased the maximum detectable strain eleven-fold over no unwrapping and the minimum detectable strain is 2.6 με. We demonstrate the potential of mechanical over optical contrast for visualizing micro-scale tissue structures in human breast cancer pathology and lymph node morphology.
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Affiliation(s)
- Brendan F. Kennedy
- Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Robert A. McLaughlin
- Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Kelsey M. Kennedy
- Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Lixin Chin
- Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Andrea Curatolo
- Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Alan Tien
- School of Surgery, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Bruce Latham
- PathWest, 197 Wellington Street, Perth, WA 6000, Australia
| | - Christobel M. Saunders
- School of Surgery, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - David D. Sampson
- Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
- Centre for Microscopy, Characterisation & Analysis, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
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28
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Wang J, Nadkarni SK. The influence of optical fiber bundle parameters on the transmission of laser speckle patterns. OPTICS EXPRESS 2014; 22:8908-18. [PMID: 24787780 DOI: 10.1364/oe.22.008908] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Laser speckle imaging (LSI) techniques provide important functional information about tissue perfusion and mechanical properties. To perform LSI in vivo, laser speckle patterns are transmitted via optical fiber bundles incorporated within small-diameter endoscopes. Inter-fiber crosstalk due to mode coupling in fiber bundles can result in erroneous speckle statistics and therefore reduces the accuracy of LSI analysis. In this paper, we investigate the influence of multiple parameters that influence crosstalk between neighboring cores within optical fiber bundles and govern the modulation of transmitted laser speckle patterns. Our results show that in addition to large core-to-core separation, large refractive index contrast between core and cladding material, reduced number of propagating modes and variability in core size are essential parameters for accurate speckle pattern transmission to conduct endoscopic LSI.
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29
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Fan X, Yun SH. The potential of optofluidic biolasers. Nat Methods 2014; 11:141-7. [PMID: 24481219 DOI: 10.1038/nmeth.2805] [Citation(s) in RCA: 265] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 11/04/2013] [Indexed: 01/05/2023]
Abstract
Optofluidic biolasers are emerging as a highly sensitive way to measure changes in biological molecules. Biolasers, which incorporate biological material into the gain medium and contain an optical cavity in a fluidic environment, can use the amplification that occurs during laser generation to quantify tiny changes in biological processes in the gain medium. We describe the principle of the optofluidic biolaser, review recent progress and provide our outlooks on potential applications and directions for developing this technology.
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Affiliation(s)
- Xudong Fan
- Biomedical Engineering Department, University of Michigan, Ann Arbor, Michigan, USA
| | - Seok-Hyun Yun
- Wellman Center for Photomedicine, Massachusetts General Hospital and Harvard Medical School, Cambridge, Massachusetts, USA
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30
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Hajjarian Z, Nadkarni SK. Correction of optical absorption and scattering variations in Laser Speckle Rheology measurements. OPTICS EXPRESS 2014; 22:6349-61. [PMID: 24663983 PMCID: PMC4083052 DOI: 10.1364/oe.22.006349] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Laser Speckle Rheology (LSR) is an optical technique to evaluate the viscoelastic properties by analyzing the temporal fluctuations of backscattered speckle patterns. Variations of optical absorption and reduced scattering coefficients further modulate speckle fluctuations, posing a critical challenge for quantitative evaluation of viscoelasticity. We compare and contrast two different approaches applicable for correcting and isolating the collective influence of absorption and scattering, to accurately measure mechanical properties. Our results indicate that the numerical approach of Monte-Carlo ray tracing (MCRT) reliably compensates for any arbitrary optical variations. When scattering dominates absorption, yet absorption is non-negligible, diffusing wave spectroscopy (DWS) formalisms perform similar to MCRT, superseding other analytical compensation approaches such as Telegrapher equation. The computational convenience of DWS greatly simplifies the extraction of viscoelastic properties from LSR measurements in a number of chemical, industrial, and biomedical applications.
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31
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Tripathi MM, Hajjarian Z, Van Cott EM, Nadkarni SK. Assessing blood coagulation status with laser speckle rheology. BIOMEDICAL OPTICS EXPRESS 2014; 5:817-31. [PMID: 24688816 PMCID: PMC3959840 DOI: 10.1364/boe.5.000817] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 12/30/2013] [Accepted: 01/02/2014] [Indexed: 05/23/2023]
Abstract
We have developed and investigated a novel optical approach, Laser Speckle Rheology (LSR), to evaluate a patient's coagulation status by measuring the viscoelastic properties of blood during coagulation. In LSR, a blood sample is illuminated with laser light and temporal speckle intensity fluctuations are measured using a high-speed CMOS camera. During blood coagulation, changes in the viscoelastic properties of the clot restrict Brownian displacements of light scattering centers within the sample, altering the rate of speckle intensity fluctuations. As a result, blood coagulation status can be measured by relating the time scale of speckle intensity fluctuations with clinically relevant coagulation metrics including clotting time and fibrinogen content. Our results report a close correlation between coagulation metrics measured using LSR and conventional coagulation results of activated partial thromboplastin time, prothrombin time and functional fibrinogen levels, creating the unique opportunity to evaluate a patient's coagulation status in real-time at the point of care.
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Affiliation(s)
- Markandey M. Tripathi
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Zeinab Hajjarian
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Elizabeth M. Van Cott
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02144, USA
| | - Seemantini K. Nadkarni
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
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Hiro T. Intravascular Molecular Imaging for Atherosclerosis. Circ J 2014; 78:1574-6. [DOI: 10.1253/circj.cj-14-0551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Takafumi Hiro
- Division of Cardiology, Department of Medicine, Nihon University School of Medicine
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Nadkarni SK. Optical measurement of arterial mechanical properties: from atherosclerotic plaque initiation to rupture. JOURNAL OF BIOMEDICAL OPTICS 2013; 18:121507. [PMID: 24296995 PMCID: PMC4696609 DOI: 10.1117/1.jbo.18.12.121507] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 10/09/2013] [Accepted: 10/10/2013] [Indexed: 05/19/2023]
Abstract
During the pathogenesis of coronary atherosclerosis, from lesion initiation to rupture, arterial mechanical properties are altered by a number of cellular, molecular, and hemodynamic processes. There is growing recognition that mechanical factors may actively drive vascular cell signaling and regulate atherosclerosis disease progression. In advanced plaques, the mechanical properties of the atheroma influence stress distributions in the fibrous cap and mediate plaque rupture resulting in acute coronary events. This review paper explores current optical technologies that provide information on the mechanical properties of arterial tissue to advance our understanding of the mechanical factors involved in atherosclerosis development leading to plaque rupture. The optical approaches discussed include optical microrheology and traction force microscopy that probe the mechanical behavior of single cell and extracellular matrix components, and intravascular imaging modalities including laser speckle rheology, optical coherence elastography, and polarization-sensitive optical coherence tomography to measure the mechanical properties of advanced coronary lesions. Given the wealth of information that these techniques can provide, optical imaging modalities are poised to play an increasingly significant role in elucidating the mechanical aspects of coronary atherosclerosis in the future.
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Affiliation(s)
- Seemantini K. Nadkarni
- Massachusetts General Hospital, Harvard Medical School, Wellman Center for Photomedicine, Boston, Massachusetts 02114
- Address all correspondence to: Seemantini K. Nadkarni, Massachusetts General Hospital, Harvard Medical School, Wellman Center for Photomedicine, Boston, Massachusetts 02114. Tel: (617)-724-1381; Fax: (617)-7264103; E-mail:
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Evaluation and correction for optical scattering variations in laser speckle rheology of biological fluids. PLoS One 2013; 8:e65014. [PMID: 23705028 PMCID: PMC3660338 DOI: 10.1371/journal.pone.0065014] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 04/22/2013] [Indexed: 11/19/2022] Open
Abstract
Biological fluids fulfill key functionalities such as hydrating, protecting, and nourishing cells and tissues in various organ systems. They are capable of these versatile tasks owing to their distinct structural and viscoelastic properties. Characterizing the viscoelastic properties of bio-fluids is of pivotal importance for monitoring the development of certain pathologies as well as engineering synthetic replacements. Laser Speckle Rheology (LSR) is a novel optical technology that enables mechanical evaluation of tissue. In LSR, a coherent laser beam illuminates the tissue and temporal speckle intensity fluctuations are analyzed to evaluate mechanical properties. The rate of temporal speckle fluctuations is, however, influenced by both optical and mechanical properties of tissue. Therefore, in this paper, we develop and validate an approach to estimate and compensate for the contributions of light scattering to speckle dynamics and demonstrate the capability of LSR for the accurate extraction of viscoelastic moduli in phantom samples and biological fluids of varying optical and mechanical properties.
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Hajjarian Z, Nadkarni SK. Depth-resolved mapping of tissue mechanical properties using a novel optical approach. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2012; 2011:5742-5. [PMID: 22255644 DOI: 10.1109/iembs.2011.6091421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Progression of most diseases, such as atherosclerosis, cancer, neurodegenerative disease and osteoarthritis is accompanied with drastic changes in biomechanics of tissue. Hence, non-contact and non-invasive technologies for 3-dimensional mapping of tissue biomechanics are invaluable for diagnostic purposes. Laser speckle Microrheology (LSM) is developed in our lab to enable high resolution mechanical evaluation of tissue. To this end, the tissue sample is illuminated by a coherent and focused laser beam and the back-scattered laser speckle pattern is spatio-temporally processed to extract a color-map of τ, which is the decay time constant of intensity decorrelation at each pixel in the image plane. Time constant, τ, is proven to be closely correlated with tissue mechanical properties. In this paper we validate the theoretical basis for LSM technology and investigate the potential for acquiring depth-resolved information from a light-scattering point of view. The patch analysis approach is introduced and the inter-relation between τ, number of scattering events, and penetration depth is explored for each patch. Axial variation of τ is characterized for two sample arterial regions and in-depth changes of mechanical properties are characterized. Finally, the required corrective measures are discussed.
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Affiliation(s)
- Zeinab Hajjarian
- Wellman Center for Photomedicine, Harvard Medical School, 40 Blossom St, Boston, MA 02114, USA.
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36
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Hajjarian Z, Nadkarni SK. Measurement of bulk mechanical properties of tissue using laser speckle rheology. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2012; 2011:5746-8. [PMID: 22255645 DOI: 10.1109/iembs.2011.6091422] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In virtually all tissues, disease progression is accompanied by changes in the mechanical properties. Laser speckle rheology (LSR) is a new technique we have developed to measure the mechanical properties of tissue. By illuminating the sample with coherent laser light and calculating the speckle intensity modulations from reflected laser speckle patterns, LSR calculates τ, the decay time constant of intensity decorrelation which is closely associated with tissue mechanical properties. In this paper we validate the use of LSR technology in measuring mechanical properties of tissue. LSR measurements of τ are performed on a variety of phantom and tissue samples and compared with the complex shear modulus G*, measured using a rheometer. In all cases, strong correlation is observed between τ and G* (r=0.95, p < 0.002). These results demonstrate the efficacy of LSR as a non-invasive and non-contact technology for mechanical evaluation of biological samples.
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Affiliation(s)
- Zeinab Hajjarian
- Wellman Center for Photomedicine, Harvard Medical School, 40 Blossom St, Boston, MA 02114, USA.
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37
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Review of laser speckle-based analysis in medical imaging. Med Biol Eng Comput 2012; 50:547-58. [PMID: 22476712 DOI: 10.1007/s11517-012-0902-z] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 03/17/2012] [Indexed: 10/28/2022]
Abstract
Speckle pattern forms when a rough object is illuminated with coherent light (laser) and the backscattered radiation is imaged on a screen. The pattern changes over time due to movement in the object. Such time-integrate speckle pattern can be statistically analyzed to reveal the flow profile. For higher velocity the speckle contrast gets reduced. This theory can be utilized for tissue perfusion in capillaries of human skin tissue and cerebral blood flow mapping in rodents. Early, the technique was suffered from low resolution and computational intricacies for real-time monitoring purpose. However, modern engineering has made it feasible for real-time monitoring in microcirculation imaging with improved resolution. This review illustrates several modifications over classical technique done by many researchers. Recent advances in speckle contrast methods gain major interest, leading towards practical implementation of this technique. The review also brings out the scopes of laser speckle-based analysis in various medical applications.
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Hajjarian Z, Nadkarni SK. Evaluating the viscoelastic properties of tissue from laser speckle fluctuations. Sci Rep 2012; 2:316. [PMID: 22428085 PMCID: PMC3306019 DOI: 10.1038/srep00316] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 02/27/2012] [Indexed: 12/29/2022] Open
Abstract
Most pathological conditions such as atherosclerosis, cancer, neurodegenerative, and orthopedic disorders are accompanied with alterations in tissue viscoelasticity. Laser Speckle Rheology (LSR) is a novel optical technology that provides the invaluable potential for mechanical assessment of tissue in situ. In LSR, the specimen is illuminated with coherent light and the time constant of speckle fluctuations, τ, is measured using a high speed camera. Prior work indicates that τ is closely correlated with tissue microstructure and composition. Here, we investigate the relationship between LSR measurements of τ and sample mechanical properties defined by the viscoelastic modulus, G*. Phantoms and tissue samples over a broad range of viscoelastic properties are evaluated using LSR and conventional mechanical testing. Results demonstrate a strong correlation between τ and |G*| for both phantom (r = 0.79, p <0.0001) and tissue (r = 0.88, p<0.0001) specimens, establishing the unique capability of LSR in characterizing tissue viscoelasticity.
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Affiliation(s)
- Zeinab Hajjarian
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School , Boston, MA
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Suter MJ, Nadkarni SK, Weisz G, Tanaka A, Jaffer FA, Bouma BE, Tearney GJ. Intravascular optical imaging technology for investigating the coronary artery. JACC Cardiovasc Imaging 2011; 4:1022-39. [PMID: 21920342 PMCID: PMC3583353 DOI: 10.1016/j.jcmg.2011.03.020] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 03/04/2011] [Accepted: 03/14/2011] [Indexed: 12/14/2022]
Abstract
There is an ever-increasing demand for new imaging methods that can provide additional information about the coronary wall to better characterize and stratify high-risk plaques, and to guide interventional and pharmacologic management of patients with coronary artery disease. While there are a number of imaging modalities that facilitate the assessment of coronary artery pathology, this review paper focuses on intravascular optical imaging modalities that provide information on the microstructural, compositional, biochemical, biomechanical, and molecular features of coronary lesions and stents. The optical imaging modalities discussed include angioscopy, optical coherence tomography, polarization sensitive-optical coherence tomography, laser speckle imaging, near-infrared spectroscopy, time-resolved laser induced fluorescence spectroscopy, Raman spectroscopy, and near-infrared fluorescence molecular imaging. Given the wealth of information that these techniques can provide, optical imaging modalities are poised to play an increasingly significant role in the evaluation of the coronary artery in the future.
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Affiliation(s)
- Melissa J. Suter
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
- Pulmonary and Critical Care Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Seemantini K. Nadkarni
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
- Pulmonary and Critical Care Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Giora Weisz
- Center for Interventional Vascular Therapy, New York-Presbyterian Hospital, Columbia University, and Cardiovascular Research Foundation, New York, New York
| | - Atsushi Tanaka
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
- Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Farouc A. Jaffer
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
- Cardiovascular Research Center, Cardiology Division, and Center for Molecular Imaging Research, Massachusetts General Hospital, Harvard Medical School, Boston Massachusetts
| | - Brett E. Bouma
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
- Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts
| | - Guillermo J. Tearney
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
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40
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Draijer M, Hondebrink E, van Leeuwen T, Steenbergen W. Time domain algorithm for accelerated determination of the first order moment of photo current fluctuations in high speed laser Doppler perfusion imaging. Med Biol Eng Comput 2011; 47:1103-9. [PMID: 19820976 PMCID: PMC2763178 DOI: 10.1007/s11517-009-0537-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Accepted: 09/19/2009] [Indexed: 12/04/2022]
Abstract
Advances in optical array sensor technology allow for the real time acquisition of dynamic laser speckle patterns generated by tissue perfusion, which, in principle, allows for real time laser Doppler perfusion imaging (LDPI). Exploitation of these developments is enhanced with the introduction of faster algorithms to transform photo currents into perfusion estimates using the first moment of the power spectrum. A time domain (TD) algorithm is presented for determining the first-order spectral moment. Experiments are performed to compare this algorithm with the widely used Fast Fourier Transform (FFT). This study shows that the TD-algorithm is twice as fast as the FFT-algorithm without loss of accuracy. Compared to FFT, the TD-algorithm is efficient in terms of processor time, memory usage and data transport.
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Affiliation(s)
- Matthijs Draijer
- Biophysical Engineering Group, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Erwin Hondebrink
- Biophysical Engineering Group, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Ton van Leeuwen
- Biophysical Engineering Group, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
- Laser Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Wiendelt Steenbergen
- Biophysical Engineering Group, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
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41
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Hajjarian Z, Xi J, Jaffer FA, Tearney GJ, Nadkarni SK. Intravascular laser speckle imaging catheter for the mechanical evaluation of the arterial wall. JOURNAL OF BIOMEDICAL OPTICS 2011; 16:026005. [PMID: 21361689 PMCID: PMC3056316 DOI: 10.1117/1.3533322] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Laser speckle imaging (LSI) is a novel technique for measuring the mechanical properties of atherosclerotic plaques. In LSI, the decorrelation time constant of speckle intensity fluctuations provides an index of viscoelasticity that is closely related to plaque microstructure and composition. Here, we demonstrate for the first time, the feasibility of conducting LSI in vivo using a prototype 1.5 mm (4.5 Fr) diameter intravascular catheter. Investigation of the catheter performance using human arterial samples ex vivo shows that plaque time constants measured by the LSI catheter correlate well with those measured using a free-space bulk optics system. To demonstrate LSI in vivo, the catheter is interfaced with a portable console for intravascular evaluation in the aorta of a living rabbit. Distinct differences in arterial time constants are identified at normal aortic and stented sites in vivo with intravascular LSI.
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Affiliation(s)
- Zeinab Hajjarian
- Massachusetts General Hospital, Wellman Center for Photomedicine, Harvard Medical School, Boston, Massachusetts 02114, USA
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42
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Wilson BC, Vitkin IA, Matthews DL. The potential of biophotonic techniques in stem cell tracking and monitoring of tissue regeneration applied to cardiac stem cell therapy. JOURNAL OF BIOPHOTONICS 2009; 2:669-681. [PMID: 19787683 DOI: 10.1002/jbio.200910079] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The use of injected stem cells, leading to regeneration of ischemic heart tissue, for example, following coronary artery occlusion, has emerged as a major new option for managing 'heart attack' patients. While some clinical trials have been encouraging, there have also been failures and there is little understanding of the multiplicity of factors that lead to the outcome. In this overview paper, the opportunities and challenges in applying biophotonic techniques to regenerative medicine, exemplified by the challenge of stem cell therapy of ischemic heart disease, are considered. The focus is on optical imaging to track stem cell distribution and fate, and optical spectroscopies and/or imaging to monitor the structural remodeling of the tissue and the resulting functional changes. The scientific, technological, and logistics issues involved in moving some of these techniques from pre-clinical research mode ultimately into the clinic are also highlighted.
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Affiliation(s)
- Brian C Wilson
- Division of Biophysics and Bioimaging, University Health Network, 610 University Ave., Toronto, ON M5G 2M9, Canada.
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43
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Le TT, Cheng JX. Non-Linear Optical Imaging of Obesity-Related Health Risks: Review. JOURNAL OF INNOVATIVE OPTICAL HEALTH SCIENCES 2009; 2:9-25. [PMID: 19784384 PMCID: PMC2750900 DOI: 10.1142/s1793545809000371] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This review highlights the recent applications of non-linear optical (NLO) microscopy to study obesity-related health risks. A strong emphasis is given to the applications of coherent anti-Stokes Raman scattering (CARS) microscopy where multiple non-linear optical imaging modalities including CARS, sum-frequency generation (SFG), and two-photon fluorescence are employed simultaneously on a single microscope platform. Specific examples on applications of NLO microscopy to study lipid-droplet biology, obesity-cancer relationship, atherosclerosis, and lipid-rich biological structures are discussed.
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Affiliation(s)
- Thuc T. Le
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, USA,
| | - Ji-Xin Cheng
- Department of Chemistry and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, USA,
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Draijer M, Hondebrink E, van Leeuwen T, Steenbergen W. Review of laser speckle contrast techniques for visualizing tissue perfusion. Lasers Med Sci 2008; 24:639-51. [PMID: 19050826 PMCID: PMC2701498 DOI: 10.1007/s10103-008-0626-3] [Citation(s) in RCA: 182] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Accepted: 10/14/2008] [Indexed: 11/27/2022]
Abstract
When a diffuse object is illuminated with coherent laser light, the backscattered light will form an interference pattern on the detector. This pattern of bright and dark areas is called a speckle pattern. When there is movement in the object, the speckle pattern will change over time. Laser speckle contrast techniques use this change in speckle pattern to visualize tissue perfusion. We present and review the contribution of laser speckle contrast techniques to the field of perfusion visualization and discuss the development of the techniques.
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Affiliation(s)
- Matthijs Draijer
- Biophysical Engineering Group Institute for Biomedical Technology, University of Twente, Enschede, The Netherlands.
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45
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Nadkarni SK, Bouma BE, Yelin D, Gulati A, Tearney GJ. Laser speckle imaging of atherosclerotic plaques through optical fiber bundles. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:054016. [PMID: 19021396 PMCID: PMC2637516 DOI: 10.1117/1.2982529] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Laser speckle imaging (LSI), a new technique that measures an index of plaque viscoelasticity, has been investigated recently to characterize atherosclerotic plaques. These prior studies demonstrated the diagnostic potential of LSI for detecting high-risk plaques and were conducted ex vivo. To conduct intracoronary LSI in vivo, the laser speckle pattern must be transmitted from the coronary wall to the image detector in the presence of cardiac motion. Small-diameter, flexible optical fiber bundles, similar to those used in coronary angioscopy, may be incorporated into an intravascular catheter for this purpose. A key challenge is that laser speckle is influenced by inter-fiber leakage of light, which may be exacerbated during bundle motion. In this study, we tested the capability of optical fiber bundles to transmit laser speckle patterns obtained from atherosclerotic plaques and evaluated the influence of motion on the diagnostic accuracy of fiber bundle-based LSI. Time-varying helium-neon laser speckle images of aortic plaques were obtained while cyclically moving the flexible length of the bundle to mimic coronary motion. Our results show that leached fiber bundles may reliably transmit laser speckle images in the presence of cardiac motion, providing a viable option to conduct intracoronary LSI.
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Affiliation(s)
- Seemantini K Nadkarni
- Harvard Medical Schooland Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
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46
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Affiliation(s)
- Yasuhiro Honda
- Center for Cardiovascular Technology, Division of Cardiovascular Medicine, Stanford University Medical Center, Stanford, Calif 94305-5637, USA
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47
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Evaluation of collagen in atherosclerotic plaques: the use of two coherent laser-based imaging methods. Lasers Med Sci 2008; 24:439-45. [PMID: 18386093 DOI: 10.1007/s10103-007-0535-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Accepted: 11/24/2007] [Indexed: 10/22/2022]
Abstract
Acute coronary events such as myocardial infarction are frequently caused by the rupture of unstable atherosclerotic plaque. Collagen plays a key role in determining plaque stability. Methods to measure plaque collagen content are invaluable in detecting unstable atherosclerotic plaques. Recently, novel coherent laser-based imaging techniques, such as polarization-sensitive optical coherence tomography (PSOCT) and laser speckle imaging (LSI) have been investigated, and they provide a wealth of information related to collagen content and plaque stability. Additionally, given their potential for intravascular use, these technologies will be invaluable for improving our understanding of the natural history of plaque development and rupture and, hence, enable the detection of unstable plaques. In this article we review recent developments in these techniques and potential challenges in translating these methods into intra-arterial use in patients.
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48
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Le TT, Langohr IM, Locker MJ, Sturek M, Cheng JX. Label-free molecular imaging of atherosclerotic lesions using multimodal nonlinear optical microscopy. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:054007. [PMID: 17994895 PMCID: PMC2646612 DOI: 10.1117/1.2795437] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Arterial tissues collected from Ossabaw swine bearing metabolic syndrome-induced cardiovascular plaques are characterized by multimodal nonlinear optical microscopy that allows coherent anti-Stokes Raman scattering, second-harmonic generation, and two-photon excitation fluorescence imaging on the same platform. Significant components of arterial walls and atherosclerotic lesions, including endothelial cells, extracellular lipid droplets, lipid-rich cells, low-density lipoprotein aggregates, collagen, and elastin are imaged without any labeling. Emission spectra of these components are obtained by nonlinear optical microspectrometry. The nonlinear optical contrast is compared with histology of the same sample. Multimodal nonlinear optical imaging of plaque composition also allows identification of atherosclerotic regions that are vulnerable to rupture risk. The demonstrated capability of nonlinear optical microscopy for label-free molecular imaging of atherosclerotic lesions with 3-D submicrometric resolution suggests its potential application to the diagnosis of atherosclerotic plaques, determination of their rupture risk, and design of individualized drug therapy based on plaque composition.
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Affiliation(s)
- Thuc T Le
- Purdue University, Weldon School of Biomedical Engineering, West Lafayette, Indiana 47907
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49
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Nadkarni SK, Pierce MC, Park BH, de Boer JF, Whittaker P, Bouma BE, Bressner JE, Halpern E, Houser SL, Tearney GJ. Measurement of collagen and smooth muscle cell content in atherosclerotic plaques using polarization-sensitive optical coherence tomography. J Am Coll Cardiol 2007; 49:1474-81. [PMID: 17397678 PMCID: PMC2785549 DOI: 10.1016/j.jacc.2006.11.040] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2006] [Revised: 10/31/2006] [Accepted: 11/27/2006] [Indexed: 10/23/2022]
Abstract
OBJECTIVES The purpose of this study was to investigate the measurement of collagen and smooth muscle cell (SMC) content in atherosclerotic plaques using polarization-sensitive optical coherence tomography (PSOCT). BACKGROUND A method capable of evaluating plaque collagen content and SMC density can provide a measure of the mechanical fidelity of the fibrous cap and can enable the identification of high-risk lesions. Optical coherence tomography has been demonstrated to provide cross-sectional images of tissue microstructure with a resolution of 10 mum. A recently developed technique, PSOCT measures birefringence, a material property that is elevated in tissues such as collagen and SMCs. METHODS We acquired PSOCT images of 87 aortic plaques obtained from 20 human cadavers. Spatially averaged PSOCT birefringence, Phi, was measured and compared with plaque collagen and SMC content, quantified morphometrically by picrosirius red and smooth muscle actin staining at the corresponding locations. RESULTS There was a high positive correlation between PSOCT measurements of Phi and total collagen content in all plaques (r = 0.67, p < 0.001) and in fibrous caps of necrotic core fibroatheromas (r = 0.68, p < 0.001). Polarization-sensitive optical coherence tomography measurements of Phi demonstrated a strong positive correlation with thick collagen fiber content (r = 0.76, p < 0.001) and SMC density (r = 0.74, p < 0.01). CONCLUSIONS Our results demonstrate that PSOCT enables the measurement of birefringence in plaques and in fibrous caps of necrotic core fibroatheromas. Given its potential to evaluate collagen content, collagen fiber thickness, and SMC density, we anticipate that PSOCT will significantly improve our ability to evaluate plaque stability in patients.
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Affiliation(s)
- Seemantini K Nadkarni
- Department of Dermatology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts, USA.
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50
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Laser Literature Watch. Photomed Laser Surg 2006; 24:222-48. [PMID: 16706704 DOI: 10.1089/pho.2006.24.222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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