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Xu H, Xia Q, Shu C, Lan J, Wang X, Gao W, Lv S, Lin R, Xie Z, Xiong X, Li F, Zhang J, Gong X. In vivo endoscopic optical coherence elastography based on a miniature probe. BIOMEDICAL OPTICS EXPRESS 2024; 15:4237-4252. [PMID: 39022537 PMCID: PMC11249679 DOI: 10.1364/boe.521154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 05/21/2024] [Accepted: 05/30/2024] [Indexed: 07/20/2024]
Abstract
Optical coherence elastography (OCE) is a functional extension of optical coherence tomography (OCT). It offers high-resolution elasticity assessment with nanoscale tissue displacement sensitivity and high quantification accuracy, promising to enhance diagnostic precision. However, in vivo endoscopic OCE imaging has not been demonstrated yet, which needs to overcome key challenges related to probe miniaturization, high excitation efficiency and speed. This study presents a novel endoscopic OCE system, achieving the first endoscopic OCE imaging in vivo. The system features the smallest integrated OCE probe with an outer diameter of only 0.9 mm (with a 1.2-mm protective tube during imaging). Utilizing a single 38-MHz high-frequency ultrasound transducer, the system induced rapid deformation in tissues with enhanced excitation efficiency. In phantom studies, the OCE quantification results match well with compression testing results, showing the system's high accuracy. The in vivo imaging of the rat vagina demonstrated the system's capability to detect changes in tissue elasticity continually and distinguish between normal tissue, hematomas, and tissue with increased collagen fibers precisely. This research narrows the gap for the clinical implementation of the endoscopic OCE system, offering the potential for the early diagnosis of intraluminal diseases.
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Affiliation(s)
- Haoxing Xu
- Research Center for Biomedical Optics and Molecular Imaging, Key Laboratory of Biomedical Imaging Science and System, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
- University of Chinese Academy of Sciences, Beijing 101408, China
| | - Qingrong Xia
- Research Center for Biomedical Optics and Molecular Imaging, Key Laboratory of Biomedical Imaging Science and System, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
- Institute of Medical Imaging, University of South China, Hengyang 421001, China
- Affiliated Nanhua Hospital, University of South China, Hengyang 421002, China
| | - Chengyou Shu
- Research Center for Biomedical Optics and Molecular Imaging, Key Laboratory of Biomedical Imaging Science and System, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Jiale Lan
- Research Center for Biomedical Optics and Molecular Imaging, Key Laboratory of Biomedical Imaging Science and System, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
- University of Chinese Academy of Sciences, Beijing 101408, China
| | - Xiatian Wang
- Research Center for Biomedical Optics and Molecular Imaging, Key Laboratory of Biomedical Imaging Science and System, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Wen Gao
- Research Center for Biomedical Optics and Molecular Imaging, Key Laboratory of Biomedical Imaging Science and System, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Shengmiao Lv
- Research Center for Biomedical Optics and Molecular Imaging, Key Laboratory of Biomedical Imaging Science and System, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Riqiang Lin
- Research Center for Biomedical Optics and Molecular Imaging, Key Laboratory of Biomedical Imaging Science and System, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Zhihua Xie
- Research Center for Biomedical Optics and Molecular Imaging, Key Laboratory of Biomedical Imaging Science and System, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Xiaohui Xiong
- University of Chinese Academy of Sciences, Beijing 101408, China
| | - Fei Li
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, China
| | - Jinke Zhang
- Research Center for Biomedical Optics and Molecular Imaging, Key Laboratory of Biomedical Imaging Science and System, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Xiaojing Gong
- Research Center for Biomedical Optics and Molecular Imaging, Key Laboratory of Biomedical Imaging Science and System, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
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Latus S, Grube S, Eixmann T, Neidhardt M, Gerlach S, Mieling R, Huttmann G, Lutz M, Schlaefer A. A Miniature Dual-Fiber Probe for Quantitative Optical Coherence Elastography. IEEE Trans Biomed Eng 2023; 70:3064-3072. [PMID: 37167045 DOI: 10.1109/tbme.2023.3275539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
OBJECTIVE Optical coherence elastography (OCE) allows for high resolution analysis of elastic tissue properties. However, due to the limited penetration of light into tissue, miniature probes are required to reach structures inside the body, e.g., vessel walls. Shear wave elastography relates shear wave velocities to quantitative estimates of elasticity. Generally, this is achieved by measuring the runtime of waves between two or multiple points. For miniature probes, optical fibers have been integrated and the runtime between the point of excitation and a single measurement point has been considered. This approach requires precise temporal synchronization and spatial calibration between excitation and imaging. METHODS We present a miniaturized dual-fiber OCE probe of 1 mm diameter allowing for robust shear wave elastography. Shear wave velocity is estimated between two optics and hence independent of wave propagation between excitation and imaging. We quantify the wave propagation by evaluating either a single or two measurement points. Particularly, we compare both approaches to ultrasound elastography. RESULTS Our experimental results demonstrate that quantification of local tissue elasticities is feasible. For homogeneous soft tissue phantoms, we obtain mean deviations of 0.15 ms-1 and 0.02 ms-1 for single-fiber and dual-fiber OCE, respectively. In inhomogeneous phantoms, we measure mean deviations of up to 0.54 ms-1 and 0.03 ms-1 for single-fiber and dual-fiber OCE, respectively. CONCLUSION We present a dual-fiber OCE approach that is much more robust in inhomogeneous tissues. Moreover, we demonstrate the feasibility of elasticity quantification in ex-vivo coronary arteries. SIGNIFICANCE This study introduces an approach for robust elasticity quantification from within the tissue.
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Singh M, Zvietcovich F, Larin KV. Introduction to optical coherence elastography: tutorial. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2022; 39:418-430. [PMID: 35297425 PMCID: PMC10052825 DOI: 10.1364/josaa.444808] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 01/25/2022] [Indexed: 06/03/2023]
Abstract
Optical coherence elastography (OCE) has seen rapid growth since its introduction in 1998. The past few decades have seen tremendous advancements in the development of OCE technology and a wide range of applications, including the first clinical applications. This tutorial introduces the basics of solid mechanics, which form the foundation of all elastography methods. We then describe how OCE measurements of tissue motion can be used to quantify tissue biomechanical parameters. We also detail various types of excitation methods, imaging systems, acquisition schemes, and data processing algorithms and how various parameters associated with each step of OCE imaging can affect the final quantitation of biomechanical properties. Finally, we discuss the future of OCE, its potential, and the next steps required for OCE to become an established medical imaging technology.
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Affiliation(s)
- Manmohan Singh
- Biomedical Engineering, University of Houston, Houston, Texas 77204, USA
| | - Fernando Zvietcovich
- Biomedical Engineering, University of Houston, Houston, Texas 77204, USA
- Department of Engineering, Pontificia Universidad Catolica del Peru, San Miguel, Lima 15088, Peru
| | - Kirill V. Larin
- Biomedical Engineering, University of Houston, Houston, Texas 77204, USA
- Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030, USA
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Liu HC, Kijanka P, Urban MW. Four-dimensional (4D) phase velocity optical coherence elastography in heterogeneous materials and biological tissue. BIOMEDICAL OPTICS EXPRESS 2020; 11:3795-3817. [PMID: 33014567 PMCID: PMC7510894 DOI: 10.1364/boe.394835] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/21/2020] [Accepted: 06/09/2020] [Indexed: 05/03/2023]
Abstract
The variations of mechanical properties in soft tissues are biomarkers used for clinical diagnosis and disease monitoring. Optical coherence elastography (OCE) has been extensively developed to investigate mechanical properties of various biological tissues. These methods are generally based on time-domain data and measure the time-of-flight of the localized shear wave propagations to estimate the group velocity. However, there is considerable information that can be obtained from examining the mechanical properties such as wave propagation velocities at different frequencies. Here we propose a method to evaluate phase velocity, wave velocity at various frequencies, in four-dimensional space (x, y, z, f), called 4D-OCE phase velocity. The method enables local estimates of the phase velocity of propagating mechanical waves in a medium. We acquired and analyzed data with this method from a homogeneous reference phantom, a heterogeneous phantom material with four different excitation cases, and ex vivo porcine kidney tissue. The 3D-OCE group velocity was also estimated to compare with 4D-OCE phase velocity. Moreover, we performed numerical simulation of wave propagations to illustrate the boundary behavior of the propagating waves. The proposed 4D-OCE phase velocity is capable of providing further information in OCE to better understand the spatial variation of mechanical properties of various biological tissues with respect to frequency.
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Affiliation(s)
- Hsiao-Chuan Liu
- Department of Radiology, Mayo Clinic, 200
First St SW, Rochester, MN 55905, USA
| | - Piotr Kijanka
- Department of Radiology, Mayo Clinic, 200
First St SW, Rochester, MN 55905, USA
- Department of Robotics and Mechatronics,
AGH University of Science and Technology, Al. Mickiewicza 30, Krakow
30-059, Poland
| | - Matthew W. Urban
- Department of Radiology, Mayo Clinic, 200
First St SW, Rochester, MN 55905, USA
- Department of Physiology and Biomedical
Engineering, Mayo Clinic, 200 First St SW, Rochester, MN 55905,
USA
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Vekilov DP, Singh M, Aglyamov SR, Larin KV, Grande-Allen KJ. Mapping the spatial variation of mitral valve elastic properties using air-pulse optical coherence elastography. J Biomech 2019; 93:52-59. [PMID: 31300156 PMCID: PMC10575695 DOI: 10.1016/j.jbiomech.2019.06.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 05/18/2019] [Accepted: 06/14/2019] [Indexed: 10/26/2022]
Abstract
The mitral valve is a highly heterogeneous tissue composed of two leaflets, anterior and posterior, whose unique composition and regional differences in material properties are essential to overall valve function. While mitral valve mechanics have been studied for many decades, traditional testing methods limit the spatial resolution of measurements and can be destructive. Optical coherence elastography (OCE) is an emerging method for measuring viscoelastic properties of tissues in a noninvasive, nondestructive manner. In this study, we employed air-pulse OCE to measure the spatial variation in mitral valve elastic properties with micro-scale resolution at 1 mm increments along the radial length of the leaflets. We analyzed differences between the leaflets, as well as between regions of the valve. We found that the anterior leaflet has a higher elastic wave velocity, which is reported as a surrogate for stiffness, than the posterior leaflet, most notably at the annular edge of the sample. In addition, we found a spatial elastic gradient in the anterior leaflet, where the annular edge was found to have a greater elastic wave velocity than the free edge. This gradient was less pronounced in the posterior leaflet. These patterns were confirmed using established uniaxial tensile testing methods. Overall, the anterior leaflet was stiffer and had greater heterogeneity in its mechanical properties than the posterior leaflet. This study measures differences between the two mitral leaflets with greater resolution than previously feasible and demonstrates a method that may be suitable for assessing valve mechanics following repair or during the engineering of synthetic valve replacements.
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Affiliation(s)
| | - Manmohan Singh
- University of Houston, Department of Biomedical Engineering, Houston, TX, United States
| | - Salavat R Aglyamov
- University of Houston, Department of Mechanical Engineering, Houston, TX, United States; University of Texas at Austin, Department of Biomedical Engineering, Austin, TX, United States
| | - Kirill V Larin
- University of Houston, Department of Biomedical Engineering, Houston, TX, United States
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Nair A, Liu CH, Singh M, Das S, Le T, Du Y, Soomro S, Aglyamov S, Mohan C, Larin KV. Assessing colitis ex vivo using optical coherence elastography in a murine model. Quant Imaging Med Surg 2019; 9:1429-1440. [PMID: 31559172 PMCID: PMC6732062 DOI: 10.21037/qims.2019.06.03] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 05/30/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) that causes regions of ulceration within the interior of the colon. UC is estimated to afflict hundreds of thousands of people in the United States alone. In addition to traditional colonoscopy, ultrasonic techniques can detect colitis, but have limited spatial resolution, which frequently results in underdiagnoses. Nevertheless, clinical diagnosis of colitis is still generally performed via colonoscopy. Optical techniques such as confocal microscopy and optical coherence tomography (OCT) have been proposed to detect UC with higher resolution. However, UC can potentially alter tissue biomechanical properties, providing additional contrast for earlier and potentially more accurate detection. Although clinically available elastography techniques have been immensely useful, they do not have the resolution for imaging small tissues, such as in small mammalian disease models. However, OCT-based elastography, optical coherence elastography (OCE), is well-suited for imaging the biomechanical properties of small mammal colon tissue. METHODS In this work, we induced elastic waves in ex vivo mouse colon tissue using a focused air-pulse. The elastic waves were detected using a phase-stabilized swept source OCE system, and the wave velocity was translated into stiffness. Measurements were taken at six positions for each sample to assess regional sample elasticity. Additional contrast between the control and diseased tissue was detected by analyzing the dispersion of the elastic wave and tissue optical properties obtained from the OCT structural image. RESULTS The results show distinct differences (P<0.05) in the stiffness between control and colitis disease samples, with a Young's modulus of 11.8±8.0 and 5.1±1.5 kPa, respectively. The OCT signal standard deviations for control and diseased samples were 5.8±0.3 and 5.5±0.2 dB, respectively. The slope of the OCT signal spatial frequency decay in the control samples was 92.7±10.0 and 87.3±4.7 dB∙µm in the colitis samples. The slope of the linearly fitted dispersion curve in the control samples was 1.5 mm, and 0.8 mm in the colitis samples. CONCLUSIONS Our results show that OCE can be utilized to distinguish tissue based on stiffness and optical properties. Our estimates of tissue stiffness suggest that the healthy colon tissue was stiffer than diseased tissue. Furthermore, structural analysis of the tissue indicates a distinct difference in tissue optical properties between the healthy and UC-like diseased tissue.
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Affiliation(s)
- Achuth Nair
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Chih Hao Liu
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Manmohan Singh
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Susobhan Das
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Triet Le
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Yong Du
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Sanam Soomro
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Salavat Aglyamov
- Department of Mechanical Engineering, University of Houston, Houston, TX, USA
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Chandra Mohan
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Kirill V. Larin
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
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