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Mekonnen T, Zevallos-Delgado C, Singh M, Aglyamov SR, Larin KV. Multifocal acoustic radiation force-based reverberant optical coherence elastography for evaluation of ocular globe biomechanical properties. JOURNAL OF BIOMEDICAL OPTICS 2023; 28:095001. [PMID: 37701876 PMCID: PMC10494982 DOI: 10.1117/1.jbo.28.9.095001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 08/01/2023] [Accepted: 08/28/2023] [Indexed: 09/14/2023]
Abstract
Significance Quantifying the biomechanical properties of the whole eye globe can provide a comprehensive understanding of the interactions among interconnected ocular components during dynamic physiological processes. By doing so, clinicians and researchers can gain valuable insights into the mechanisms underlying ocular diseases, such as glaucoma, and design interventions tailored to each patient's unique needs. Aim The aim of this study was to evaluate the feasibility and effectiveness of a multifocal acoustic radiation force (ARF) based reverberant optical coherence elastography (RevOCE) technique for quantifying shear wave speeds in different ocular components simultaneously. Approach We implemented a multifocal ARF technique to generate reverberant shear wave fields, which were then detected using phase-sensitive optical coherence tomography. A 3D-printed acoustic lens array was employed to manipulate a collimated ARF beam generated by an ultrasound transducer, producing multiple focused ARF beams on mouse eye globes ex vivo. RevOCE measurements were conducted using an excitation pulse train consisting of 10 cycles at 3 kHz, followed by data processing to produce a volumetric map of the shear wave speed. Results The results show that the system can successfully generate reverberant shear wave fields in the eye globe, allowing for simultaneous estimation of shear wave speeds in various ocular components, including cornea, iris, lens, sclera, and retina. A comparative analysis revealed notable differences in wave speeds between different parts of the eye, for example, between the apical region of the cornea and the pupillary zone of the iris (p = 0.003 ). Moreover, the study also revealed regional variations in the biomechanical properties of ocular components as evidenced by greater wave speeds near the apex of the cornea compared to its periphery. Conclusions The study demonstrated the effectiveness of RevOCE based on a non-invasive multifocal ARF for assessing the biomechanical properties of the whole eyeball. The findings indicate the potential to provide a comprehensive understanding of the mechanical behavior of the whole eye, which could lead to improved diagnosis and treatment of ocular diseases.
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Affiliation(s)
- Taye Mekonnen
- University of Houston, Department of Biomedical Engineering Houston, Texas, United States
| | | | - Manmohan Singh
- University of Houston, Department of Biomedical Engineering Houston, Texas, United States
| | - Salavat R. Aglyamov
- University of Houston, Department of Mechanical Engineering, Houston, Texas, United States
| | - Kirill V. Larin
- University of Houston, Department of Biomedical Engineering Houston, Texas, United States
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2
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Lan G, Shi Q, Wang Y, Ma G, Cai J, Feng J, Huang Y, Gu B, An L, Xu J, Qin J, Twa MD. Spatial Assessment of Heterogeneous Tissue Natural Frequency Using Micro-Force Optical Coherence Elastography. Front Bioeng Biotechnol 2022; 10:851094. [PMID: 35360399 PMCID: PMC8962667 DOI: 10.3389/fbioe.2022.851094] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Accepted: 02/28/2022] [Indexed: 11/20/2022] Open
Abstract
Analysis of corneal tissue natural frequency was recently proposed as a biomarker for corneal biomechanics and has been performed using high-resolution optical coherence tomography (OCT)-based elastography (OCE). However, it remains unknown whether natural frequency analysis can resolve local variations in tissue structure. We measured heterogeneous samples to evaluate the correspondence between natural frequency distributions and regional structural variations. Sub-micrometer sample oscillations were induced point-wise by microliter air pulses (60–85 Pa, 3 ms) and detected correspondingly at each point using a 1,300 nm spectral domain common path OCT system with 0.44 nm phase detection sensitivity. The resulting oscillation frequency features were analyzed via fast Fourier transform and natural frequency was characterized using a single degree of freedom (SDOF) model. Oscillation features at each measurement point showed a complex frequency response with multiple frequency components that corresponded with global structural features; while the variation of frequency magnitude at each location reflected the local sample features. Silicone blocks (255.1 ± 11.0 Hz and 249.0 ± 4.6 Hz) embedded in an agar base (355.6 ± 0.8 Hz and 361.3 ± 5.5 Hz) were clearly distinguishable by natural frequency. In a beef shank sample, central fat and connective tissues had lower natural frequencies (91.7 ± 58.2 Hz) than muscle tissue (left side: 252.6 ± 52.3 Hz; right side: 161.5 ± 35.8 Hz). As a first step, we have shown the possibility of natural frequency OCE methods to characterize global and local features of heterogeneous samples. This method can provide additional information on corneal properties, complementary to current clinical biomechanical assessments, and could become a useful tool for clinical detection of ocular disease and evaluation of medical or surgical treatment outcomes.
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Affiliation(s)
- Gongpu Lan
- School of Physics and Optoelectronic Engineering, Foshan University, Foshan, China
- Innovation and Entrepreneurship Teams of Guangdong Pearl River Talents Program, Weiren Meditech Co., Ltd., Foshan, China
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, Foshan University, Foshan, China
- *Correspondence: Gongpu Lan, ; Michael D. Twa,
| | - Qun Shi
- School of Mechatronic Engineering and Automation, Foshan University, Foshan, China
| | - Yicheng Wang
- School of Mechatronic Engineering and Automation, Foshan University, Foshan, China
| | - Guoqin Ma
- School of Mechatronic Engineering and Automation, Foshan University, Foshan, China
| | - Jing Cai
- School of Physics and Optoelectronic Engineering, Foshan University, Foshan, China
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, Foshan University, Foshan, China
| | - Jinping Feng
- Institute of Engineering and Technology, Hubei University of Science and Technology, Xianning, China
| | - Yanping Huang
- School of Physics and Optoelectronic Engineering, Foshan University, Foshan, China
- Innovation and Entrepreneurship Teams of Guangdong Pearl River Talents Program, Weiren Meditech Co., Ltd., Foshan, China
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, Foshan University, Foshan, China
| | - Boyu Gu
- School of Computer and Information Engineering, Tianjin Chengjian University, Tianjin, China
| | - Lin An
- Innovation and Entrepreneurship Teams of Guangdong Pearl River Talents Program, Weiren Meditech Co., Ltd., Foshan, China
| | - Jingjiang Xu
- School of Physics and Optoelectronic Engineering, Foshan University, Foshan, China
- Innovation and Entrepreneurship Teams of Guangdong Pearl River Talents Program, Weiren Meditech Co., Ltd., Foshan, China
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, Foshan University, Foshan, China
| | - Jia Qin
- Innovation and Entrepreneurship Teams of Guangdong Pearl River Talents Program, Weiren Meditech Co., Ltd., Foshan, China
| | - Michael D. Twa
- College of Optometry, University of Houston, Houston, TX, United States
- *Correspondence: Gongpu Lan, ; Michael D. Twa,
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Zemzemi C, Catheline S, Turquier F. Shear wave elastography biases in abdominal wall layers characterization. Phys Med Biol 2021; 66. [PMID: 34560674 DOI: 10.1088/1361-6560/ac29cd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 09/24/2021] [Indexed: 11/12/2022]
Abstract
Ventral incisional hernia repair is one of the most common surgical procedures. The characterization of the abdominal wall layer mechanical properties is the first step towards personalized treatment. This study investigates the capability of elastography to assess these properties using anin vivoandin vitromodel of abdominal wall layers. Two experiment approaches are considered: shear wave elastography imaging and guided wave dispersion characterization, where the latter is used as a reference. Results show measurement biases in the shear wave elastography approach in such a layer structure configuration. Methods to overcome these biases are suggested to improve and to correct the elastography approach for abdominal wall layers and similar anatomical structures.
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Affiliation(s)
- C Zemzemi
- LabTAU, INSERM, Centre Léon Bérard, Université Lyon 1, Univ-Lyon, F-69003, Lyon, France
| | - S Catheline
- LabTAU, INSERM, Centre Léon Bérard, Université Lyon 1, Univ-Lyon, F-69003, Lyon, France
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Singh M, Schill AW, Nair A, Aglyamov SR, Larina IV, Larin KV. Ultra-fast dynamic line-field optical coherence elastography. OPTICS LETTERS 2021; 46:4742-4744. [PMID: 34598188 PMCID: PMC9121022 DOI: 10.1364/ol.435278] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 08/20/2021] [Indexed: 05/12/2023]
Abstract
In this work, we present an ultra-fast line-field optical coherence elastography system (LF-OCE) with an 11.5 MHz equivalent A-line rate. The system was composed of a line-field spectral domain optical coherence tomography system based on a supercontinuum light source, Michelson-type interferometer, and a high-speed 2D spectrometer. The system performed ultra-fast imaging of elastic waves in tissue-mimicking phantoms of various elasticities. The results corroborated well with mechanical testing. Following validation, LF-OCE measurements were made in in situ and in in vivo rabbit corneas under various conditions. The results show the capability of the system to rapidly image elastic waves in tissues.
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Affiliation(s)
- Manmohan Singh
- Biomedical Engineering, University of Houston, 3517 Cullen Blvd., Room 2027, Houston, Texas 77204, USA
| | - Alexander W. Schill
- Biomedical Engineering, University of Houston, 3517 Cullen Blvd., Room 2027, Houston, Texas 77204, USA
| | - Achuth Nair
- Biomedical Engineering, University of Houston, 3517 Cullen Blvd., Room 2027, Houston, Texas 77204, USA
| | - Salavat R. Aglyamov
- Mechanical Engineering, University of Houston, 4726 Calhoun Rd., N207 Engineering Building 1, Houston, Texas 77204, USA
| | - Irina V. Larina
- Molecular Physiology and Biophysics, Baylor College of Medicine, 1 Baylor Plaza, Houston, Texas 77030, USA
| | - Kirill V. Larin
- Biomedical Engineering, University of Houston, 3517 Cullen Blvd., Room 2027, Houston, Texas 77204, USA
- Molecular Physiology and Biophysics, Baylor College of Medicine, 1 Baylor Plaza, Houston, Texas 77030, USA
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Batchelor WM, Heilman BM, Arrieta-Quintero E, Ruggeri M, Parel JM, Manns F, Cabrera-Ghayouri S, Dibas M, Ziebarth NM. Measuring the effects of postmortem time and age on mouse lens elasticity using atomic force microscopy. Exp Eye Res 2021; 212:108768. [PMID: 34534541 DOI: 10.1016/j.exer.2021.108768] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 09/09/2021] [Accepted: 09/12/2021] [Indexed: 11/25/2022]
Abstract
The mouse lens is frequently used both in vivo and ex vivo in ophthalmic research to model conditions affecting the human lens, such as presbyopia. The mouse lens has a delicate structure which is prone to damage and biomechanical changes both before and after extraction from the whole globe. When not properly controlled for, these changes can confound the biomechanical analysis of mouse lenses. In this study, atomic force microscopy microindentation was used to assess changes in the Young's Modulus of Elasticity of the mouse lens as a function of mouse age and postmortem time. Old mouse lenses measured immediately postmortem were significantly stiffer than young mouse lenses (p = 0.028). However, after 18 h of incubation, there was no measurable difference in lens stiffness between old and young mouse lenses (p = 0.997). This demonstrates the need for careful experimental control in experiments using the mouse lens, especially regarding postmortem time.
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Affiliation(s)
- Wyndham More Batchelor
- Biomedical Atomic Force Microscopy Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, Miami, FL, USA
| | - Bianca Maceo Heilman
- Biomedical Atomic Force Microscopy Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, Miami, FL, USA; Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Esdras Arrieta-Quintero
- Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Marco Ruggeri
- Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Jean-Marie Parel
- Biomedical Atomic Force Microscopy Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, Miami, FL, USA; Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA; Brien Holden Vision Institute, University of New South Wales, Sydney, Australia
| | - Fabrice Manns
- Biomedical Atomic Force Microscopy Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, Miami, FL, USA; Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | | | | | - Noel Marysa Ziebarth
- Biomedical Atomic Force Microscopy Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, Miami, FL, USA.
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Marmin A, Laloy-Borgna G, Facca S, Gioux S, Catheline S, Nahas A. Time-of-flight and noise-correlation-inspired algorithms for full-field shear-wave elastography using digital holography. JOURNAL OF BIOMEDICAL OPTICS 2021; 26:JBO-210039RR. [PMID: 34414704 PMCID: PMC8374320 DOI: 10.1117/1.jbo.26.8.086006] [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: 02/03/2021] [Accepted: 07/26/2021] [Indexed: 06/13/2023]
Abstract
SIGNIFICANCE Quantitative stiffness information can be a powerful aid for tumor or fibrosis diagnosis. Currently, very promising elastography approaches developed for non-contact biomedical imaging are based on transient shear-waves imaging. Transient elastography offers quantitative stiffness information by tracking the propagation of a wave front. The most common method used to compute stiffness from the acquired propagation movie is based on shear-wave time-of-flight calculations. AIM We introduce an approach to transient shear-wave elastography with spatially coherent sources, able to yield full-field quantitative stiffness maps with reduced artifacts compared to typical artifacts observed in time-of-flight. APPROACH A noise-correlation algorithm developed for passive elastography is adapted to spatially coherent narrow or any band sources. This noise-correlation-inspired (NCi) method is employed in parallel with a classic time-of-flight approach. Testing is done on simulation images, experimental validation is conducted with a digital holography setup on controlled homogeneous samples, and full-field quantitative stiffness maps are presented for heterogeneous samples and ex-vivo biological tissues. RESULTS The NCi approach is first validated on simulations images. Stiffness images processed by the NCi approach on simulated inclusions display significantly less artifacts than with a time-of-flight reconstruction. The adaptability of the NCi algorithm to narrow or any band shear-wave sources was tested successfully. Experimental testing on homogeneous samples demonstrates similar values for both the time-of-flight and the NCi approach. Soft inclusions in agarose sample could be resolved using the NCi method and feasibility on ex-vivo biological tissues is presented. CONCLUSIONS The presented NCi approach was successful in computing quantitative full-field stiffness maps with narrow and broadband source signals on simulation and experimental images from a digital holography setup. Results in heterogeneous media show that the NCi approach could provide stiffness maps with less artifacts than with time-of-flight, demonstrating that a NCi algorithm is a promising approach for shear-wave transient elastography with spatially coherent sources.
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Affiliation(s)
- Agathe Marmin
- The University of Strasbourg, ICUBE Research Institute, Strasbourg, France
| | | | - Sybille Facca
- The University of Strasbourg, ICUBE Research Institute, Strasbourg, France
- University Hospital of Strasbourg, FMTS, ICube CNRS 7357, University of Strasbourg, Department of Hand Surgery, SOS hand, Strasbourg, France
| | - Sylvain Gioux
- The University of Strasbourg, ICUBE Research Institute, Strasbourg, France
| | | | - Amir Nahas
- The University of Strasbourg, ICUBE Research Institute, Strasbourg, France
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7
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Zvietcovich F, Singh M, Ambekar YS, Aglyamov SR, Twa MD, Larin KV. Micro Air-Pulse Spatial Deformation Spreading Characterizes Degree of Anisotropy in Tissues. IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS : A PUBLICATION OF THE IEEE LASERS AND ELECTRO-OPTICS SOCIETY 2021; 27:6800810. [PMID: 33994766 PMCID: PMC8117953 DOI: 10.1109/jstqe.2020.3038633] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
In optical coherence elastography (OCE), air-pulse stimulation has been widely used to produce propagation of mechanical waves for elastic characterization of tissues. In this paper, we propose the use of spatial deformation spreading (SDS) on the surface of samples produced by air-pulse stimulation for the OCE of transverse isotropic tissues. Experiments in isotropic tissue-mimicking phantoms and anisotropic chicken tibialis muscle were conducted using a spectral-domain optical coherence tomography system synchronized with a confocal air-pulse stimulation. SDS measurements were compared with wave speeds values calculated at different propagation angles. We found an approximately linear relationship between shear wave speed and SDS in isotropic phantoms, which was confirmed with predictions made by the numerical integration of a wave propagation model. Experimental measurements in chicken muscle show a good agreement between SDS and surface wave speed taken along and across the axis of symmetry of the tissues, also called degree of anisotropy. In summary, these results demonstrated the capabilities of SDS produced by the air-pulse technique in measuring the shear elastic anisotropy of transverse isotropic tissues.
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Affiliation(s)
- Fernando Zvietcovich
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204 USA
| | - Manmohan Singh
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204 USA
| | - Yogeshwari S Ambekar
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204 USA
| | - Salavat R Aglyamov
- Department of Mechanical Engineering, University of Houston, Houston, TX 77204 USA
| | - Michael D Twa
- College of Optometry, University of Houston, Houston, TX 77204 USA
| | - Kirill V Larin
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204 USA
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8
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An Intraocular Pressure Measurement Technique Based on Acoustic Radiation Force Using an Ultrasound Transducer: A Feasibility Study. SENSORS 2021; 21:s21051857. [PMID: 33799942 PMCID: PMC7961774 DOI: 10.3390/s21051857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 03/02/2021] [Accepted: 03/03/2021] [Indexed: 11/16/2022]
Abstract
High intraocular pressure (IOP) is one of the major risk factors for glaucoma, and thus accurate IOP measurements should be performed to diagnose and treat glaucoma early. In this study, a novel technique for measuring the IOP based on acoustic radiation force was proposed, and its potential was experimentally demonstrated. The proposed technique uses the acoustic radiation force to generate axial displacement on the ocular surface while simultaneously measuring the degree of deformation. In order to verify that the ocular displacement induced by the acoustic radiation force is related to the IOP, the experiment was conducted by fabricating a 5 MHz single element transducer and gelatin phantoms with different stiffness values. Our experimental results show that there is a close relationship between the ocular displacement by the acoustic radiation force and the IOP obtained by a commercial tonometer. Therefore, the proposed acoustic radiation force technique can be a promising candidate for measuring the IOP.
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Lan G, Aglyamov SR, Larin KV, Twa MD. In Vivo Human Corneal Shear-wave Optical Coherence Elastography. Optom Vis Sci 2021; 98:58-63. [PMID: 33394932 PMCID: PMC7774819 DOI: 10.1097/opx.0000000000001633] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 09/24/2020] [Indexed: 01/01/2023] Open
Abstract
SIGNIFICANCE A novel imaging technology, dynamic optical coherence elastography (OCE), was adapted for clinical noninvasive measurements of corneal biomechanics. PURPOSE Determining corneal biomechanical properties is a long-standing challenge. Elasticity imaging methods have recently been developed and applied for clinical evaluation of soft tissues in cancer detection, atherosclerotic plaque evaluation, surgical guidance, and more. Here, we describe the use of dynamic OCE to characterize mechanical wave propagation in the human cornea in vivo, thus providing a method for clinical determination of corneal biomechanical properties. METHODS High-resolution phase-sensitive optical coherence tomography imaging was combined with microliter air-pulse tissue stimulation to perform dynamic elasticity measurements in 18 eyes of nine participants. Low-pressure (0.1 mmHg), spatiotemporally discreet (150 μm, 800 μs) tissue stimulation produced submicron-scale tissue deformations that were measured at multiple positions over a 1-mm2 area. Surface wave velocity was measured and used to determine tissue stiffness. Elastic wave propagation velocity was measured and evaluated as a function of IOP and central corneal thickness. RESULTS Submicron corneal surface displacement amplitude (range, 0.005 to 0.5 μm) responses were measured with high sensitivity (0.24 nm). Corneal elastic wave velocity ranged from 2.4 to 4.2 m/s (mean, 3.5; 95% confidence interval, 3.2 to 3.8 m/s) and was correlated with central corneal thickness (r = 0.64, P < .001) and IOP (r = 0.52, P = .02). CONCLUSIONS Phase-sensitive optical coherence tomography imaging combined with microliter air-pulse mechanical tissue stimulation has sufficient detection sensitivity to observe submicron elastic wave propagation in corneal tissue. These measurements enable in vivo corneal stiffness determinations that will be further studied for use with disease detection and for monitoring clinical interventions.
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Affiliation(s)
- Gongpu Lan
- School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong, China
- University of Houston College of Optometry, Houston, Texas
| | | | - Kirill V. Larin
- Department of Biomedical Engineering, University of Houston, Houston, Texas
| | - Michael D. Twa
- University of Houston College of Optometry, Houston, Texas
- School of Optometry, University of Alabama at Birmingham, Birmingham, Alabama
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Jin Z, Chen S, Dai Y, Bao C, Ye S, Zhou Y, Wang Y, Huang S, Wang Y, Shen M, Zhu D, Lu F. In vivo noninvasive measurement of spatially resolved corneal elasticity in human eyes using Lamb wave optical coherence elastography. JOURNAL OF BIOPHOTONICS 2020; 13:e202000104. [PMID: 32368840 DOI: 10.1002/jbio.202000104] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 04/24/2020] [Accepted: 04/29/2020] [Indexed: 05/23/2023]
Abstract
Current elastography techniques are limited in application to accurately assess spatially resolved corneal elasticity in vivo for human eyes. The air-puff optical coherence elastography (OCE) with an eye motion artifacts correction algorithm is developed to distinguish the in vivo cornea vibration from the eye motion and visualize the Lamb wave propagation clearly in healthy subjects. Based on the Lamb wave model, the phase velocity dispersion curve in the high-frequency is calculated to obtain spatially resolved corneal elasticity accurately with high repeatability. It is found that the corneal elasticity has regional variations and is correlated with intraocular pressure, which suggests that the method has the potential to provide noninvasive measurement of spatially resolved corneal elasticity in clinical practice.
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Affiliation(s)
- Zi Jin
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Sisi Chen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Yingying Dai
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Chenhong Bao
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Shuling Ye
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Yuheng Zhou
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Yiyi Wang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Shenghai Huang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Yuanyuan Wang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Meixiao Shen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Dexi Zhu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Fan Lu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
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Lan G, Larin KV, Aglyamov S, Twa MD. Characterization of natural frequencies from nanoscale tissue oscillations using dynamic optical coherence elastography. BIOMEDICAL OPTICS EXPRESS 2020; 11:3301-3318. [PMID: 32637256 PMCID: PMC7316029 DOI: 10.1364/boe.391324] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 05/01/2020] [Accepted: 05/12/2020] [Indexed: 05/09/2023]
Abstract
We demonstrate the use of OCT-based elastography for soft-tissue characterization using natural frequency oscillations. Sub-micrometer to sub-nanometer oscillations were induced in tissue phantoms and human cornea in vivo by perpendicular air-pulse stimulation and observed by common-path OCT imaging (sensitivity: 0.24 nm). Natural frequency and damping ratio were acquired in temporal and frequency domains using a single degree of freedom method. The dominant natural frequency was constant for different stimulation pressures (4-32 Pa) and measured distances (0.3-5.3 mm), and decreased as the sample thickness increased. The dominant natural frequencies of 0.75-2% agar phantoms were 127-774 Hz (mean coefficient of variation [CV]: 0.9%), and correlated with the square root of Young's moduli (16.5-117.8 kPa, mean CV: 5.8%). These preliminary studies show repeatable in vivo corneal natural frequency measurements (259 Hz, CV: 1.9%). This novel OCE approach can distinguish tissues and materials with different mechanical properties using the small-amplitude tissue oscillation features, and is suitable for characterizing delicate tissues in vivo such as the eye.
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Affiliation(s)
- Gongpu Lan
- Foshan University, School of Physics and Optoelectronic Engineering, Foshan, Guangdong, 528000, China
- University of Alabama at Birmingham, School of Optometry, Birmingham, AL 35290, USA
- University of Houston, College of Optometry, Houston, TX 77204, USA
| | - Kirill V. Larin
- University of Houston, Biomedical Engineering, Houston, TX 77204, USA
| | - Salavat Aglyamov
- University of Houston, Mechanical Engineering, Houston, TX 77204, USA
| | - Michael D. Twa
- University of Alabama at Birmingham, School of Optometry, Birmingham, AL 35290, USA
- University of Houston, College of Optometry, Houston, TX 77204, USA
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12
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Lan G, Gu B, Larin KV, Twa MD. Clinical Corneal Optical Coherence Elastography Measurement Precision: Effect of Heartbeat and Respiration. Transl Vis Sci Technol 2020; 9:3. [PMID: 32821475 PMCID: PMC7401940 DOI: 10.1167/tvst.9.5.3] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 11/30/2019] [Indexed: 01/29/2023] Open
Abstract
Purpose Normal physiological movements (e.g., respiration and heartbeat) induce eye motions during clinical measurements of human corneal biomechanical properties using optical coherence elastography (OCE). We quantified the effects of respiratory and cardiac-induced eye motions on clinical corneal OCE measurement precision and repeatability. Methods Corneal OCE was performed using low-force, micro-air-pulse tissue stimulation and high-resolution phase-sensitive optical coherence tomography (OCT) imaging. Axial surface displacements of the corneal apex were measured (M-mode) at a 70-kHz sampling rate and three different stimulation pressures (20-60 Pa). Simultaneously, the axial corneal position was tracked with structural OCT imaging, while the heartrate and respiration were monitored over a 90 second period. Results Respiratory- and cardiac-induced eye motions have distinctly lower frequency (0.1-1 Hz) and much greater amplitude (up to ± 50 µm movements) than air-pulse-induced corneal tissue deformations (∼250 Hz, <1 µm). The corneal displacements induced during OCE measurements in vivo were -0.41 ± 0.06 µm (n = 22 measurements, coefficient of variation [CV]: 14.6%) and -0.44 ± 0.07 µm (n = 50 measurements, CV: 15.9%), respectively, from two human subjects at 40 Pa stimulation pressure. Observed variation in corneal tissue displacements were not associated with tissue stimulation magnitude, or the amplitude of physiologically induced axial eye motion. Conclusions The microsecond timescale and submicron tissue displacements observed during corneal OCE measurements are separable from normal involuntary physiological movements, such as the oculocardiac pulse and respiratory movements. Translational Relevance This work advances innovations in biomedical imaging and engineering for clinical diagnostic applications for soft-tissue biomechanical testing.
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Affiliation(s)
- Gongpu Lan
- Department of Photoelectric Technology, Foshan University, Foshan, Guangdong, China.,School of Optometry, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Boyu Gu
- Department of Ophthalmology, Doheny Eye Institute, University of California -Los Angeles, Los Angeles, CA, USA
| | - Kirill V Larin
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Michael D Twa
- School of Optometry, University of Alabama at Birmingham, Birmingham, AL, USA.,College of Optometry, University of Houston, Houston, TX, USA
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Jin Z, Khazaeinezhad R, Zhu J, Yu J, Qu Y, He Y, Li Y, Gomez Alvarez-Arenas TE, Lu F, Chen Z. In-vivo 3D corneal elasticity using air-coupled ultrasound optical coherence elastography. BIOMEDICAL OPTICS EXPRESS 2019; 10:6272-6285. [PMID: 31853399 PMCID: PMC6913398 DOI: 10.1364/boe.10.006272] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 10/03/2019] [Accepted: 10/10/2019] [Indexed: 05/03/2023]
Abstract
Corneal elasticity can resist elastic deformations under intraocular pressure to maintain normal corneal shape, which has a great influence on corneal refractive function. Elastography can measure tissue elasticity and provide a powerful tool for clinical diagnosis. Air-coupled ultrasound optical coherence elastography (OCE) has been used in the quantification of ex-vivo corneal elasticity. However, in-vivo imaging of the cornea remains a challenge. The 3D air-coupled ultrasound OCE with an axial motion artifacts correction algorithm was developed to distinguish the in-vivo cornea vibration from the axial eye motion in anesthetized rabbits and visualize the elastic wave propagation clearly. The elastic wave group velocity of in-vivo rabbit cornea was measured to be 5.96 ± 0.55 m/s, which agrees with other studies. The results show the potential of 3D air-coupled ultrasound OCE with an axial motion artifacts correction algorithm for quantitative in-vivo assessment of corneal elasticity.
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Affiliation(s)
- Zi Jin
- Beckman Laser Institute, Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92612, USA
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou 325003, Zhejiang, China
- These authors contributed equally to this work
| | - Reza Khazaeinezhad
- Beckman Laser Institute, Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92612, USA
- These authors contributed equally to this work
| | - Jiang Zhu
- Beckman Laser Institute, Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92612, USA
| | - Junxiao Yu
- Beckman Laser Institute, Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92612, USA
| | - Yueqiao Qu
- Beckman Laser Institute, Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92612, USA
| | - Youmin He
- Beckman Laser Institute, Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92612, USA
| | - Yan Li
- Beckman Laser Institute, Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92612, USA
| | - Tomas E Gomez Alvarez-Arenas
- Institute of Physical and Information Technologies, Spanish National Research Council (CSIC), 28006 Madrid, Spain
| | - Fan Lu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou 325003, Zhejiang, China
| | - Zhongping Chen
- Beckman Laser Institute, Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92612, USA
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Thieulin C, Pailler-Mattei C, Abdouni A, Djaghloul M, Zahouani H. Mechanical and topographical anisotropy for human skin: Ageing effect. J Mech Behav Biomed Mater 2019; 103:103551. [PMID: 32090946 DOI: 10.1016/j.jmbbm.2019.103551] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 10/30/2019] [Accepted: 11/20/2019] [Indexed: 11/25/2022]
Abstract
Skin ageing is a complex process which strongly impacts the three skin layers (epidermis, dermis, hypodermis) both functionally and structurally. Of particular interest are the effects of ageing on the dermis biomechanics and how this evolution can impact the reorganization of the cutaneous lines which compose the skin relief. It has been argued that the skin relief could reflect the underlying mechanical condition of the skin. Nevertheless, there is not yet conclusive evidence of the existence of such a link. This work aims at experimentally studying, in vivo, the correlation between the anisotropy of human skin biomechanics and skin topography as a function of ageing. The study was conducted on a panel of 20 men divided into 4 groups according to age (from 23 to 64 years old). The measurements were performed on the right volar forearm of each volunteer. For the biomechanical measurements, an innovative contactless bio-rheometer was developed. It allows access to the mechanical behaviour of the skin in several directions. This device generates an air blast without any contact with the skin area and measures its dynamic response (evaluation of speed of wave propagation) with a linear laser. Moreover, a turntable enables measurements to be made in different angular directions. To analyse the topography of skin relief, we proposed a new method, based on watershed and linear radon transformations. First, an optical analysis of a replica of the skin relief is performed. Then, from the skin image obtained, the density of the cutaneous lines is calculated in different directions using watersheld transformation. The orientation of the detected lines is then estimated with an algorithm based on linear radon transformation. The results observed show a good correlation between the skin relief and the mechanical properties of the skin all along the ageing process. For both topography and mechanical properties, there is a transition from an almost isotropic mechanical behaviour to an anisotropic one as a function of ageing process. Thus, we might conclude that the skin relief reflects the underlying mechanical conditions of the skin.
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Affiliation(s)
- C Thieulin
- Laboratoire de Tribologie et Dynamique des Systèmes, UMR-CNRS 5513, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, Ecully, France.
| | - C Pailler-Mattei
- Laboratoire de Tribologie et Dynamique des Systèmes, UMR-CNRS 5513, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, Ecully, France; Université de Lyon, Faculté de Pharmacie-ISPB, Laboratoire de Biophysique, Lyon, France
| | - A Abdouni
- Laboratoire de Tribologie et Dynamique des Systèmes, UMR-CNRS 5513, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, Ecully, France
| | - M Djaghloul
- Laboratoire de Tribologie et Dynamique des Systèmes, UMR-CNRS 5513, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, Ecully, France
| | - H Zahouani
- Laboratoire de Tribologie et Dynamique des Systèmes, UMR-CNRS 5513, Ecole Centrale de Lyon, 36 Avenue Guy de Collongue, Ecully, France
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Zhou Y, Wang Y, Shen M, Jin Z, Chen Y, Zhou Y, Qu J, Zhu D. In vivo evaluation of corneal biomechanical properties by optical coherence elastography at different cross-linking irradiances. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-7. [PMID: 31605471 PMCID: PMC7000888 DOI: 10.1117/1.jbo.24.10.105001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 09/06/2019] [Indexed: 05/18/2023]
Abstract
Corneal collagen cross-linking (CXL) strengthens the biomechanical properties of damaged corneas. Quantifying the changes of stiffness due to different CXL protocols is difficult, especially in vivo. A noninvasive elastic wave-based optical coherence elastography system was developed to construct in vivo corneal elasticity maps by excitation of air puff. Biomechanical differences were compared for rabbit corneas given three different CXL protocols while keeping the total energy delivered constant. The Young’s modulus was weaker in corneas treated with higher irradiance levels over shorter durations, and a slight increase of Young’s modulus was present in all groups one week after the recovery process. Due to the noninvasive nature and minimal force to generate corneal elastic waves, this technique has the potential for early detection and treatment of corneal diseases in clinic.
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Affiliation(s)
- Yuheng Zhou
- Wenzhou Medical University, School of Ophthalmology and Optometry, Wenzhou, China
| | - Yuanyuan Wang
- Wenzhou Medical University, School of Ophthalmology and Optometry, Wenzhou, China
| | - Meixiao Shen
- Wenzhou Medical University, School of Ophthalmology and Optometry, Wenzhou, China
| | - Zi Jin
- Wenzhou Medical University, School of Ophthalmology and Optometry, Wenzhou, China
| | - Yihong Chen
- Wenzhou Medical University, School of Ophthalmology and Optometry, Wenzhou, China
| | - Yue Zhou
- Wenzhou Medical University, School of Ophthalmology and Optometry, Wenzhou, China
| | - Jia Qu
- Wenzhou Medical University, School of Ophthalmology and Optometry, Wenzhou, China
| | - Dexi Zhu
- Wenzhou Medical University, School of Ophthalmology and Optometry, Wenzhou, China
- Address all correspondence to Dexi Zhu, E-mail:
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Effects of Thickness on Corneal Biomechanical Properties Using Optical Coherence Elastography. Optom Vis Sci 2019; 95:299-308. [PMID: 29561496 DOI: 10.1097/opx.0000000000001193] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
SIGNIFICANCE Measured corneal biomechanical properties are driven by intraocular pressure, tissue thickness, and inherent material properties. We demonstrate tissue thickness as an important factor in the measurement of corneal biomechanics that can confound short-term effects due to UV riboflavin cross-linking (CXL) treatment. PURPOSE We isolate the effects of tissue thickness on the measured corneal biomechanical properties using optical coherence elastography by experimentally altering the tissue hydration state and stiffness. METHODS Dynamic optical coherence elastography was performed using phase-sensitive optical coherence tomography imaging to quantify the tissue deformation dynamics resulting from a spatially discrete, low-force air pulse (150-μm spot size; 0.8-millisecond duration; <10 Pa [<0.08 mmHg]). The time-dependent surface deformation is characterized by a viscoelastic tissue recovery response, quantified by an exponential decay constant-relaxation rate. Ex vivo rabbit globes (n = 10) with fixed intraocular pressure (15 mmHg) were topically instilled every 5 minutes with 0.9% saline for 60 minutes and 20% dextran for another 60 minutes. Measurements were made after every 20 minutes to determine the central corneal thickness (CCT) and the relaxation rates. Cross-linking treatment was performed on another 13 eyes, applying isotonic riboflavin (n = 6) and hypertonic riboflavin (n = 7) every 5 minutes for 30 minutes, followed by UV irradiation (365 nm, 3 mW/cm) for 30 minutes while instilling riboflavin. Central corneal thickness and relaxation rates were obtained before and after CXL treatment. RESULTS Corneal thickness was positively correlated (R = 0.9) with relaxation rates. In the CXL-treated eyes, isotonic riboflavin did not affect CCT and showed a significant increase in relaxation rates (+10%; P = .01) from 2.29 ms to 2.53 ms. Hypertonic riboflavin showed a significant CCT decrease (-31%; P = .01) from 618 μm to 429 μm but showed little change in relaxation rates after CXL treatment. CONCLUSIONS Corneal thickness and stiffness are correlated positively. A higher relaxation rate implied stiffer material properties after isotonic CXL treatment. Hypertonic CXL treatment results in a stiffness decrease that offsets the stiffness increase with CXL treatment.
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17
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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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18
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Kazaili A, Lawman S, Geraghty B, Eliasy A, Zheng Y, Shen Y, Akhtar R. Line-Field Optical Coherence Tomography as a tool for In vitro characterization of corneal biomechanics under physiological pressures. Sci Rep 2019; 9:6321. [PMID: 31004101 PMCID: PMC6474860 DOI: 10.1038/s41598-019-42789-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 04/03/2019] [Indexed: 12/02/2022] Open
Abstract
There has been a lot of interest in accurately characterising corneal biomechanical properties under intraocular pressure (IOP) to help better understand ocular pathologies that are associated with elevated IOP. This study investigates the novel use of Line-Field Optical Coherence Tomography (LF-OCT) as an elastographic tool for accurately measuring mechanical properties of porcine corneas based on volumetric deformation following varying IOPs. A custom-built LF-OCT was used to measure geometrical and corneal surface displacement changes in porcine corneas under a range of IOPs, from 0-60 mmHg. Corneal thickness, elastic properties and hysteresis were calculated as a function of pressure. In addition, the effects of hydration were explored. We found that the elastic modulus increased in a linear fashion with IOP. Corneal thickness was found to reduce with IOP, decreasing 14% from 0 to 60 mmHg. Prolonged hydration in phosphate buffered saline (PBS) was found to significantly increase the elastic modulus and corneal hysteresis. Our study demonstrates that LF-OCT can be used to accurately measure the elastic properties based on volumetric deformation following physiological pressures. Furthermore, we show that prolonged hydration in PBS has a significant effect on the measured corneal properties.
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Affiliation(s)
- Ahmed Kazaili
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, Liverpool, L69 3GH, UK
- Department of Biomedical Engineering, College of Engineering, University of Babylon, Hillah, Iraq
| | - Samuel Lawman
- Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, L69 3GJ, UK
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, L7 8TX, UK
| | - Brendan Geraghty
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, L7 8TX, UK
| | - Ashkan Eliasy
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, Liverpool, L69 3GH, UK
| | - Yalin Zheng
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, L7 8TX, UK
| | - Yaochun Shen
- Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, L69 3GJ, UK
| | - Riaz Akhtar
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, Liverpool, L69 3GH, UK.
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Zaitsev VY, Matveyev AL, Matveev LA, Gelikonov GV, Baum OI, Omelchenko AI, Shabanov DV, Sovetsky AA, Yuzhakov AV, Fedorov AA, Siplivy VI, Bolshunov AV, Sobol EN. Revealing structural modifications in thermomechanical reshaping of collagenous tissues using optical coherence elastography. JOURNAL OF BIOPHOTONICS 2019; 12:e201800250. [PMID: 30417604 DOI: 10.1002/jbio.201800250] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 10/06/2018] [Accepted: 11/06/2018] [Indexed: 05/20/2023]
Abstract
Moderate heating of such collagenous tissues as cornea and cartilages by infra-red laser (IR laser) irradiation is an emerging technology for nondestructive modification of the tissue shape and microstructure for a variety of applications in ophthalmology, otolaryngology and so on. Postirradiation high-resolution microscopic examination indicates the appearance of microscopic either spheroidal or crack-like narrow pores depending on the tissue type and irradiation regime. Such examinations usually require special tissue preparation (eg, staining, drying that affect microstructure themselves) and are mostly suitable for studying individual pores, whereas evaluation of their averaged parameters, especially in situ, is challenging. Here, we demonstrate the ability of optical coherence tomography (OCT) to visualize areas of pore initiation and evaluate their averaged properties by combining visualization of residual irradiation-induced tissue dilatation and evaluation of the accompanying Young-modulus reduction by OCT-based compressional elastography. We show that the averaged OCT-based data obtained in situ fairly well agree with the microscopic examination results. The results obtained develop the basis for effective and safe applications of novel nondestructive laser technologies of tissue modification in clinical practice. PICTURE: Elastographic OCT-based images of an excised rabbit eye cornea subjected to thermomechanical laser-assisted reshaping. Central panel shows resultant cumulative dilatation in cornea after moderate (~45-50°C) pulse-periodic heating by an IR laser together with distribution of the inverse Young modulus 1/E before (left) and after (right) IR irradiation. Significant modulus decrease in the center of irradiated region is caused by initiated micropores. Their parameters can be extracted by analyzing the elastographic images.
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Affiliation(s)
- Vladimir Y Zaitsev
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - Alexander L Matveyev
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - Lev A Matveev
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - Grigory V Gelikonov
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - Olga I Baum
- Institute of Photon Technologies, Federal Scientific Research Centre "Crystallography and Photonics", Russian Academy of Sciences, Moscow, Russia
| | - Alexander I Omelchenko
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
- Institute of Photon Technologies, Federal Scientific Research Centre "Crystallography and Photonics", Russian Academy of Sciences, Moscow, Russia
| | - Dmitry V Shabanov
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - Alexander A Sovetsky
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | - Alexey V Yuzhakov
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
- Institute of Photon Technologies, Federal Scientific Research Centre "Crystallography and Photonics", Russian Academy of Sciences, Moscow, Russia
| | | | | | | | - Emil N Sobol
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
- Institute of Photon Technologies, Federal Scientific Research Centre "Crystallography and Photonics", Russian Academy of Sciences, Moscow, Russia
- IPG Medical Corporation, Marlborough, Massachusetts
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Zhang H, Wu C, Singh M, Nair A, Aglyamov SR, Larin KV. Optical coherence elastography of cold cataract in porcine lens. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-7. [PMID: 30864348 PMCID: PMC6444576 DOI: 10.1117/1.jbo.24.3.036004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 02/19/2019] [Indexed: 05/08/2023]
Abstract
Cataract is one of the most prevalent causes of blindness around the world. Understanding the mechanisms of cataract development and progression is important for clinical diagnosis and treatment. Cold cataract has proven to be a robust model for cataract formation that can be easily controlled in the laboratory. There is evidence that the biomechanical properties of the lens can be significantly changed by cataract. Therefore, early detection of cataract, as well as evaluation of therapies, could be guided by characterization of lenticular biomechanical properties. In this work, we utilized optical coherence elastography (OCE) to monitor the changes in biomechanical properties of ex vivo porcine lenses during formation of cold cataract. Elastic waves were induced in the porcine lenses by a focused micro air-pulse while the lenses were cooled, and the elastic wave velocity was translated to Young's modulus of the lens. The results show an increase in the stiffness of the lens due to formation of the cold cataract (from 11.3 ± 3.4 to 21.8 ± 7.8 kPa). These results show a relation between lens opacity and stiffness and demonstrate that OCE can assess lenticular biomechanical properties and may be useful for detecting and potentially characterizing cataracts.
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Affiliation(s)
- Hongqiu Zhang
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
| | - Chen Wu
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
| | - Manmohan Singh
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
| | - Achuth Nair
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
| | - Salavat R. Aglyamov
- University of Houston, Department of Mechanical Engineering, Houston, Texas, United States
- University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Kirill V. Larin
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
- Address all correspondence to Kirill V. Larin, E-mail:
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22
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Lan G, Singh M, Larin KV, Twa MD. Common-path phase-sensitive optical coherence tomography provides enhanced phase stability and detection sensitivity for dynamic elastography. BIOMEDICAL OPTICS EXPRESS 2017; 8:5253-5266. [PMID: 29188118 PMCID: PMC5695968 DOI: 10.1364/boe.8.005253] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 10/16/2017] [Accepted: 10/23/2017] [Indexed: 05/08/2023]
Abstract
Phase-sensitive optical coherence elastography (PhS-OCE) is an emerging optical technique to quantify soft-tissue biomechanical properties. We implemented a common-path OCT design to enhance displacement sensitivity and optical phase stability for dynamic elastography imaging. The background phase stability was greater in common-path PhS-OCE (0.24 ± 0.07nm) than conventional PhS-OCE (1.60 ± 0.11μm). The coefficient of variation for surface displacement measurements using conventional PhS-OCE averaged 11% versus 2% for common-path PhS-OCE. Young's modulus estimates showed good precision (95% CIs) for tissue phantoms: 24.96 ± 2.18kPa (1% agar), 49.69 ± 4.87kPa (1.5% agar), and 116.08 ± 12.14kPa (2% agar), respectively. Common-path PhS-OCE effectively reduced the amplitude of background dynamic optical phase instability to a sub-nanometer level, which provided a larger dynamic detection range and higher detection sensitivity for surface displacement measurements than conventional PhS-OCE.
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Affiliation(s)
- Gongpu Lan
- School of Optometry, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Manmohan Singh
- Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Kirill V. Larin
- Biomedical Engineering, University of Houston, Houston, TX, USA
- Interdisciplinary Laboratory of Biophotonics, Tomsk State University, Tomsk, Russia
| | - Michael D. Twa
- School of Optometry, University of Alabama at Birmingham, Birmingham, AL, USA
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Singh M, Li J, Vantipalli S, Han Z, Larin KV, Twa MD. Optical coherence elastography for evaluating customized riboflavin/UV-A corneal collagen crosslinking. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:91504. [PMID: 28055060 PMCID: PMC5995143 DOI: 10.1117/1.jbo.22.9.091504] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 11/15/2016] [Indexed: 05/02/2023]
Abstract
UV-induced collagen cross-linking is a promising treatment for keratoconus that stiffens corneal tissue and prevents further degeneration. Since keratoconus is generally localized, the efficacy of collagen cross-linking (CXL) treatments could be improved by stiffening only the weakened parts of the cornea. Here, we demonstrate that optical coherence elastography (OCE) can spatially resolve transverse variations in corneal stiffness. A short duration ( ? 1 ?? ms ) focused air-pulse induced low amplitude ( ? 10 ?? ? m ) deformations in the samples that were detected using a phase-stabilized optical coherence tomography system. A two-dimensional map of material stiffness was generated by measuring the damped natural frequency (DNF) of the air-pulse induced response at various transverse locations of a heterogeneous phantom mimicking a customized CXL treatment. After validation on the phantoms, similar OCE measurements were made on spatially selective CXL-treated in situ rabbit corneas. The results showed that this technique was able to clearly distinguish the untreated and CXL-treated regions of the cornea, where CXL increased the DNF of the cornea by ? 51 % . Due to the noncontact nature and minimal excitation force, this technique may be valuable for in vivo assessments of corneal biomechanical properties.
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Affiliation(s)
- Manmohan Singh
- University of Houston, Biomedical Engineering, 3517 Cullen Boulevard, Room 2027, Houston, Texas 77204, United States
| | - Jiasong Li
- University of Houston, Biomedical Engineering, 3517 Cullen Boulevard, Room 2027, Houston, Texas 77204, United States
| | - Srilatha Vantipalli
- University of Houston, Department of Optometry, 4901 Calhoun Road, Houston, Texas 77204, United States
| | - Zhaolong Han
- University of Houston, Biomedical Engineering, 3517 Cullen Boulevard, Room 2027, Houston, Texas 77204, United States
| | - Kirill V. Larin
- University of Houston, Biomedical Engineering, 3517 Cullen Boulevard, Room 2027, Houston, Texas 77204, United States
- Baylor College of Medicine, Molecular Physiology and Biophysics, One Baylor Plaza, Houston, Texas 77030, United States
- Samara State Aerospace University, Electrical and Computer Engineering, 34, Moskovskoye shosse, Samara 443086, Russia
| | - Michael D. Twa
- University of Alabama at Birmingham, School of Optometry, 1716 University Boulevard, Birmingham, Alabama 35233, United States
- Address all correspondence to: Michael D. Twa,
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Ocular fundus pulsations within the posterior rat eye: Chorioscleral motion and response to elevated intraocular pressure. Sci Rep 2017; 7:8780. [PMID: 28821834 PMCID: PMC5562765 DOI: 10.1038/s41598-017-09310-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 07/25/2017] [Indexed: 12/13/2022] Open
Abstract
A multi-functional optical coherence tomography (OCT) approach is presented to determine ocular fundus pulsations as an axial displacement between the retina and the chorioscleral complex in the albino rat eye. By combining optical coherence elastography and OCT angiography (OCTA), we measure subtle deformations in the nanometer range within the eye and simultaneously map retinal and choroidal perfusion. The conventional OCT reflectivity contrast serves as a backbone to segment the retina and to define several slabs which are subsequently used for quantitative ocular pulsation measurements as well as for a qualitative exploration of the multi-functional OCT image data. The proposed concept is applied in healthy albino rats as well as in rats under acute elevation of the intraocular pressure (IOP). The evaluation of this experiment revealed an increased pulsatility and deformation between the retinal and chorioscleral complex while increasing the IOP level from 15 mmHg to 65 mmHg. At IOP levels exceeding 65 mmHg, the pulsatility decreased significantly and retinal as well as choroidal perfusion vanished in OCTA. Furthermore, the evaluation of the multi-parametric experiment revealed a spatial correlation between fundus pulsatility and choroidal blood flow. This indicates that the assessed pulsatility may be a valuable parameter describing the choroidal perfusion.
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25
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Zvietcovich F, Rolland JP, Yao J, Meemon P, Parker KJ. Comparative study of shear wave-based elastography techniques in optical coherence tomography. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:35010. [PMID: 28358943 DOI: 10.1117/1.jbo.22.3.035010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 03/15/2017] [Indexed: 05/03/2023]
Abstract
We compare five optical coherence elastography techniques able to estimate the shear speed of waves generated by one and two sources of excitation. The first two techniques make use of one piezoelectric actuator in order to produce a continuous shear wave propagation or a tone-burst propagation (TBP) of 400 Hz over a gelatin tissue-mimicking phantom. The remaining techniques utilize a second actuator located on the opposite side of the region of interest in order to create three types of interference patterns: crawling waves, swept crawling waves, and standing waves, depending on the selection of the frequency difference between the two actuators. We evaluated accuracy, contrast to noise ratio, resolution, and acquisition time for each technique during experiments. Numerical simulations were also performed in order to support the experimental findings. Results suggest that in the presence of strong internal reflections, single source methods are more accurate and less variable when compared to the two-actuator methods. In particular, TBP reports the best performance with an accuracy error < 4.1 % . Finally, the TBP was tested in a fresh chicken tibialis anterior muscle with a localized thermally ablated lesion in order to evaluate its performance in biological tissue.
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Affiliation(s)
- Fernando Zvietcovich
- University of Rochester, Department of Electrical and Computer Engineering, Rochester, New York, United States
| | - Jannick P Rolland
- University of Rochester, The Institute of Optics, Rochester, New York, United States
| | - Jianing Yao
- University of Rochester, The Institute of Optics, Rochester, New York, United States
| | - Panomsak Meemon
- University of Rochester, The Institute of Optics, Rochester, New York, United StatescSuranaree University of Technology, School of Physics, Institute of Science, Nakhon Ratchasima, Thailand
| | - Kevin J Parker
- University of Rochester, Department of Electrical and Computer Engineering, Rochester, New York, United States
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Larin KV, Sampson DD. Optical coherence elastography - OCT at work in tissue biomechanics [Invited]. BIOMEDICAL OPTICS EXPRESS 2017; 8:1172-1202. [PMID: 28271011 PMCID: PMC5330567 DOI: 10.1364/boe.8.001172] [Citation(s) in RCA: 203] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 01/18/2017] [Accepted: 01/19/2017] [Indexed: 05/18/2023]
Abstract
Optical coherence elastography (OCE), as the use of OCT to perform elastography has come to be known, began in 1998, around ten years after the rest of the field of elastography - the use of imaging to deduce mechanical properties of tissues. After a slow start, the maturation of OCT technology in the early to mid 2000s has underpinned a recent acceleration in the field. With more than 20 papers published in 2015, and more than 25 in 2016, OCE is growing fast, but still small compared to the companion fields of cell mechanics research methods, and medical elastography. In this review, we describe the early developments in OCE, and the factors that led to the current acceleration. Much of our attention is on the key recent advances, with a strong emphasis on future prospects, which are exceptionally bright.
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Affiliation(s)
- Kirill V Larin
- 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, 1 Baylor Plaza, Houston, Texas 77030, USA;
| | - David D Sampson
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia; Centre for Microscopy, Characterisation & Analysis, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia;
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27
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Nguyen TM, Zorgani A, Lescanne M, Boccara C, Fink M, Catheline S. Diffuse shear wave imaging: toward passive elastography using low-frame rate spectral-domain optical coherence tomography. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:126013. [PMID: 27999863 DOI: 10.1117/1.jbo.21.12.126013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 12/01/2016] [Indexed: 05/18/2023]
Abstract
Optical coherence tomography (OCT) can map the stiffness of biological tissue by imaging mechanical perturbations (shear waves) propagating in the tissue. Most shear wave elastography (SWE) techniques rely on active shear sources to generate controlled displacements that are tracked at ultrafast imaging rates. Here, we propose a noise-correlation approach to retrieve stiffness information from the imaging of diffuse displacement fields using low-frame rate spectral-domain OCT. We demonstrated the method on tissue-mimicking phantoms and validated the results by comparison with classic ultrafast SWE. Then we investigated the in vivo feasibility on the eye of an anesthetized rat by applying noise correlation to naturally occurring displacements. The results suggest a great potential for passive elastography based on the detection of natural pulsatile motions using conventional spectral-domain OCT systems. This would facilitate the transfer of OCT-elastography to clinical practice, in particular, in ophthalmology or dermatology.
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Affiliation(s)
- Thu-Mai Nguyen
- Institut Langevin Ondes et Images, ESPCI Paris, Université Paris-Sciences-Lettres, CNRS UMR 7587, Inserm U979-1 rue Jussieu, 75005 Paris, France
| | - Ali Zorgani
- Laboratory of Therapeutic Applications of Ultrasound, Inserm U1032-151 cours Albert Thomas, 69003 Lyon, France
| | - Maxime Lescanne
- Laboratory of Therapeutic Applications of Ultrasound, Inserm U1032-151 cours Albert Thomas, 69003 Lyon, France
| | - Claude Boccara
- Institut Langevin Ondes et Images, ESPCI Paris, Université Paris-Sciences-Lettres, CNRS UMR 7587, Inserm U979-1 rue Jussieu, 75005 Paris, France
| | - Mathias Fink
- Institut Langevin Ondes et Images, ESPCI Paris, Université Paris-Sciences-Lettres, CNRS UMR 7587, Inserm U979-1 rue Jussieu, 75005 Paris, France
| | - Stefan Catheline
- Laboratory of Therapeutic Applications of Ultrasound, Inserm U1032-151 cours Albert Thomas, 69003 Lyon, France
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Han Z, Li J, Singh M, Wu C, Liu CH, Raghunathan R, Aglyamov SR, Vantipalli S, Twa MD, Larin KV. Optical coherence elastography assessment of corneal viscoelasticity with a modified Rayleigh-Lamb wave model. J Mech Behav Biomed Mater 2016; 66:87-94. [PMID: 27838594 DOI: 10.1016/j.jmbbm.2016.11.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 10/27/2016] [Accepted: 11/02/2016] [Indexed: 01/22/2023]
Abstract
The biomechanical properties of the cornea play a critical role in forming vision. Diseases such as keratoconus can structurally degenerate the cornea causing a pathological loss in visual acuity. UV-A/riboflavin corneal collagen crosslinking (CXL) is a clinically available treatment to stiffen the cornea and restore its healthy shape and function. However, current CXL techniques do not account for pre-existing biomechanical properties of the cornea nor the effects of the CXL treatment itself. In addition to the inherent corneal structure, the intraocular pressure (IOP) can also dramatically affect the measured biomechanical properties of the cornea. In this work, we present the details and development of a modified Rayleigh-Lamb frequency equation model for quantifying corneal biomechanical properties. After comparison with finite element modeling, the model was utilized to quantify the viscoelasticity of in situ porcine corneas in the whole eye-globe configuration before and after CXL based on noncontact optical coherence elastography measurements. Moreover, the viscoelasticity of the untreated and CXL-treated eyes was quantified at various IOPs. The results showed that the stiffness of the cornea increased after CXL and that corneal stiffness is close to linear as a function of IOP. These results show that the modified Rayleigh-Lamb wave model can provide an accurate assessment of corneal viscoelasticity, which could be used for customized CXL therapies.
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Affiliation(s)
- Zhaolong Han
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, United States
| | - Jiasong Li
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, United States
| | - Manmohan Singh
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, United States
| | - Chen Wu
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, United States
| | - Chih-Hao Liu
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, United States
| | - Raksha Raghunathan
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, United States
| | - Salavat R Aglyamov
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78712, United States
| | - Srilatha Vantipalli
- College of Optometry, University of Houston, Houston, TX 77204, United States
| | - Michael D Twa
- School of Optometry, University of Alabama at Birmingham, Birmingham, AL 35233, United States
| | - Kirill V Larin
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, United States; Interdisciplinary Laboratory of Biophotonics, Tomsk State University, Tomsk, Russia; Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, United States.
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29
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Material Properties from Air Puff Corneal Deformation by Numerical Simulations on Model Corneas. PLoS One 2016; 11:e0165669. [PMID: 27792759 PMCID: PMC5085055 DOI: 10.1371/journal.pone.0165669] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 10/14/2016] [Indexed: 01/27/2023] Open
Abstract
OBJECTIVE To validate a new method for reconstructing corneal biomechanical properties from air puff corneal deformation images using hydrogel polymer model corneas and porcine corneas. METHODS Air puff deformation imaging was performed on model eyes with artificial corneas made out of three different hydrogel materials with three different thicknesses and on porcine eyes, at constant intraocular pressure of 15 mmHg. The cornea air puff deformation was modeled using finite elements, and hyperelastic material parameters were determined through inverse modeling, minimizing the difference between the simulated and the measured central deformation amplitude and central-peripheral deformation ratio parameters. Uniaxial tensile tests were performed on the model cornea materials as well as on corneal strips, and the results were compared to stress-strain simulations assuming the reconstructed material parameters. RESULTS The measured and simulated spatial and temporal profiles of the air puff deformation tests were in good agreement (< 7% average discrepancy). The simulated stress-strain curves of the studied hydrogel corneal materials fitted well the experimental stress-strain curves from uniaxial extensiometry, particularly in the 0-0.4 range. Equivalent Young´s moduli of the reconstructed material properties from air-puff were 0.31, 0.58 and 0.48 MPa for the three polymer materials respectively which differed < 1% from those obtained from extensiometry. The simulations of the same material but different thickness resulted in similar reconstructed material properties. The air-puff reconstructed average equivalent Young´s modulus of the porcine corneas was 1.3 MPa, within 18% of that obtained from extensiometry. CONCLUSIONS Air puff corneal deformation imaging with inverse finite element modeling can retrieve material properties of model hydrogel polymer corneas and real corneas, which are in good correspondence with those obtained from uniaxial extensiometry, suggesting that this is a promising technique to retrieve quantitative corneal biomechanical properties.
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30
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Singh M, Li J, Vantipalli S, Wang S, Han Z, Nair A, Aglyamov SR, Twa MD, Larin KV. Noncontact Elastic Wave Imaging Optical Coherence Elastography for Evaluating Changes in Corneal Elasticity Due to Crosslinking. IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS : A PUBLICATION OF THE IEEE LASERS AND ELECTRO-OPTICS SOCIETY 2016. [PMID: 27547022 DOI: 10.1109/jqe.2016.2585338] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The mechanical properties of tissues can provide valuable information about tissue integrity and health and can assist in detecting and monitoring the progression of diseases such as keratoconus. Optical coherence elastography (OCE) is a rapidly emerging technique, which can assess localized mechanical contrast in tissues with micrometer spatial resolution. In this work we present a noncontact method of optical coherence elastography to evaluate the changes in the mechanical properties of the cornea after UV-induced collagen cross-linking. A focused air-pulse induced a low amplitude (μm scale) elastic wave, which then propagated radially and was imaged in three dimensions by a phase-stabilized swept source optical coherence tomography (PhS-SSOCT) system. The elastic wave velocity was translated to Young's modulus in agar phantoms of various concentrations. Additionally, the speed of the elastic wave significantly changed in porcine cornea before and after UV-induced corneal collagen cross-linking (CXL). Moreover, different layers of the cornea, such as the anterior stroma, posterior stroma, and inner region, could be discerned from the phase velocities of the elastic wave. Therefore, because of noncontact excitation and imaging, this method may be useful for in vivo detection of ocular diseases such as keratoconus and evaluation of therapeutic interventions such as CXL.
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Affiliation(s)
- Manmohan Singh
- Department of Biomedical Engineering at the University of Houston, Houston, TX 77204 USA
| | - Jiasong Li
- Department of Biomedical Engineering at the University of Houston, Houston, TX 77204 USA
| | | | - Shang Wang
- Department of Molecular Physiology and Biophysics at Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030 USA
| | - Zhaolong Han
- Department of Biomedical Engineering at the University of Houston, Houston, TX 77204 USA
| | - Achuth Nair
- Department of Biomedical Engineering at the University of Houston, Houston, TX 77004 USA
| | - Salavat R Aglyamov
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78731 USA
| | - Michael D Twa
- School of Optometry at the University of Alabama at Birmingham, Birmingham, AL 35924
| | - Kirill V Larin
- Department of Biomedical Engineering at the University of Houston, Houston, TX 77004 USA and and the Interdisciplinary Laboratory of Biophotonics, Tomsk State University, Tomsk 634050, Russia, phone: 832-842-8834; fax: 713-743-0226
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31
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Singh M, Li J, Vantipalli S, Wang S, Han Z, Nair A, Aglyamov SR, Twa MD, Larin KV. Noncontact Elastic Wave Imaging Optical Coherence Elastography for Evaluating Changes in Corneal Elasticity Due to Crosslinking. IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS : A PUBLICATION OF THE IEEE LASERS AND ELECTRO-OPTICS SOCIETY 2016; 22:6801911. [PMID: 27547022 PMCID: PMC4990138 DOI: 10.1109/jstqe.2015.2510293] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The mechanical properties of tissues can provide valuable information about tissue integrity and health and can assist in detecting and monitoring the progression of diseases such as keratoconus. Optical coherence elastography (OCE) is a rapidly emerging technique, which can assess localized mechanical contrast in tissues with micrometer spatial resolution. In this work we present a noncontact method of optical coherence elastography to evaluate the changes in the mechanical properties of the cornea after UV-induced collagen cross-linking. A focused air-pulse induced a low amplitude (μm scale) elastic wave, which then propagated radially and was imaged in three dimensions by a phase-stabilized swept source optical coherence tomography (PhS-SSOCT) system. The elastic wave velocity was translated to Young's modulus in agar phantoms of various concentrations. Additionally, the speed of the elastic wave significantly changed in porcine cornea before and after UV-induced corneal collagen cross-linking (CXL). Moreover, different layers of the cornea, such as the anterior stroma, posterior stroma, and inner region, could be discerned from the phase velocities of the elastic wave. Therefore, because of noncontact excitation and imaging, this method may be useful for in vivo detection of ocular diseases such as keratoconus and evaluation of therapeutic interventions such as CXL.
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Affiliation(s)
| | | | | | - Shang Wang
- Department of Molecular Physiology and Biophysics at Baylor College
of Medicine, One Baylor Plaza, Houston, TX 77030 USA
| | - Zhaolong Han
- Department of Biomedical Engineering at the University of Houston,
Houston, TX 77204 USA
| | - Achuth Nair
- Department of Biomedical Engineering at the University of Houston,
Houston, TX 77004 USA
| | - Salavat R. Aglyamov
- Department of Biomedical Engineering, University of Texas at
Austin, Austin, TX 78731 USA
| | - Michael D. Twa
- School of Optometry at the University of Alabama at Birmingham,
Birmingham, AL 35924
| | - Kirill V. Larin
- Department of Biomedical Engineering at the University of Houston,
Houston, TX 77004 USA and and the Interdisciplinary Laboratory of
Biophotonics, Tomsk State University, Tomsk 634050, Russia, phone:
832-842-8834; fax: 713-743-0226
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32
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Han Z, Li J, Singh M, Wu C, Liu CH, Wang S, Idugboe R, Raghunathan R, Sudheendran N, Aglyamov SR, Twa MD, Larin KV. Quantitative methods for reconstructing tissue biomechanical properties in optical coherence elastography: a comparison study. Phys Med Biol 2015; 60:3531-47. [PMID: 25860076 PMCID: PMC4409577 DOI: 10.1088/0031-9155/60/9/3531] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We present a systematic analysis of the accuracy of five different methods for extracting the biomechanical properties of soft samples using optical coherence elastography (OCE). OCE is an emerging noninvasive technique, which allows assessment of biomechanical properties of tissues with micrometer spatial resolution. However, in order to accurately extract biomechanical properties from OCE measurements, application of a proper mechanical model is required. In this study, we utilize tissue-mimicking phantoms with controlled elastic properties and investigate the feasibilities of four available methods for reconstructing elasticity (Young's modulus) based on OCE measurements of an air-pulse induced elastic wave. The approaches are based on the shear wave equation (SWE), the surface wave equation (SuWE), Rayleigh-Lamb frequency equation (RLFE), and finite element method (FEM), Elasticity values were compared with uniaxial mechanical testing. The results show that the RLFE and the FEM are more robust in quantitatively assessing elasticity than the other simplified models. This study provides a foundation and reference for reconstructing the biomechanical properties of tissues from OCE data, which is important for the further development of noninvasive elastography methods.
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Affiliation(s)
- Zhaolong Han
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX 77204, USA
| | - Jiasong Li
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX 77204, USA
| | - Manmohan Singh
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX 77204, USA
| | - Chen Wu
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX 77204, USA
| | - Chih-hao Liu
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX 77204, USA
| | - Shang Wang
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX 77204, USA
- Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Rita Idugboe
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX 77204, USA
| | - Raksha Raghunathan
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX 77204, USA
| | - Narendran Sudheendran
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX 77204, USA
| | - Salavat R. Aglyamov
- Department of Biomedical Engineering, University of Texas at Austin, 107 W Dean Keeton Street, Austin, TX 78712, USA
| | - Michael D. Twa
- School of Optometry, University of Alabama, Birmingham, AL 35294 USA
| | - Kirill V. Larin
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX 77204, USA
- Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
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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: 126] [Impact Index Per Article: 14.0] [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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34
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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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35
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Nguyen TM, Arnal B, Song S, Huang Z, Wang RK, O’Donnell M. Shear wave elastography using amplitude-modulated acoustic radiation force and phase-sensitive optical coherence tomography. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:016001. [PMID: 25554970 PMCID: PMC4282275 DOI: 10.1117/1.jbo.20.1.016001] [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: 10/08/2014] [Accepted: 12/04/2014] [Indexed: 05/03/2023]
Abstract
Investigating the elasticity of ocular tissue (cornea and intraocular lens) could help the understanding and management of pathologies related to biomechanical deficiency. In previous studies, we introduced a setup based on optical coherence tomography for shear wave elastography (SWE) with high resolution and high sensitivity. SWE determines tissue stiffness from the propagation speed of shear waves launched within tissue. We proposed acoustic radiation force to remotely induce shear waves by focusing an ultrasound (US) beam in tissue, similar to several elastography techniques. Minimizing the maximum US pressure is essential in ophthalmology for safety reasons. For this purpose, we propose a pulse compression approach. It utilizes coded US emissions to generate shear waves where the energy is spread over a long emission, and then numerically compressed into a short, localized, and high-energy pulse. We used a 7.5-MHz single-element focused transducer driven by coded excitations where the amplitude is modulated by a linear frequency-swept square wave (1 to 7 kHz). An inverse filter approach was used for compression. We demonstrate the feasibility of performing shear wave elastography measurements in tissue-mimicking phantoms at low US pressures (mechanical index < 0.6)
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Affiliation(s)
- Thu-Mai Nguyen
- University of Washington, Department of Bioengineering, 3720 15th Avenue NE, P.O. Box 355013, Seattle, Washington 98105, United States
- Address all correspondence to: Thu-Mai Nguyen, E-mail:
| | - Bastien Arnal
- University of Washington, Department of Bioengineering, 3720 15th Avenue NE, P.O. Box 355013, Seattle, Washington 98105, United States
| | - Shaozhen Song
- University of Washington, Department of Bioengineering, 3720 15th Avenue NE, P.O. Box 355013, Seattle, Washington 98105, United States
- University of Dundee, School of Engineering, Departments of Physics and Mathematics, Fulton Building, Dundee DD1 4HN, United Kingdom
| | - Zhihong Huang
- University of Dundee, School of Engineering, Departments of Physics and Mathematics, Fulton Building, Dundee DD1 4HN, United Kingdom
| | - Ruikang K. Wang
- University of Washington, Department of Bioengineering, 3720 15th Avenue NE, P.O. Box 355013, Seattle, Washington 98105, United States
- University of Washington, Department of Ophthalmology, 325 9th Avenue, Seattle, Washington 98104, United States
| | - Matthew O’Donnell
- University of Washington, Department of Bioengineering, 3720 15th Avenue NE, P.O. Box 355013, Seattle, Washington 98105, United States
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Chin L, Curatolo A, Kennedy BF, Doyle BJ, Munro PRT, McLaughlin RA, Sampson DD. Analysis of image formation in optical coherence elastography using a multiphysics approach. BIOMEDICAL OPTICS EXPRESS 2014; 5:2913-30. [PMID: 25401007 PMCID: PMC4230875 DOI: 10.1364/boe.5.002913] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 07/17/2014] [Accepted: 07/23/2014] [Indexed: 05/18/2023]
Abstract
IMAGE FORMATION IN OPTICAL COHERENCE ELASTOGRAPHY (OCE) RESULTS FROM A COMBINATION OF TWO PROCESSES: the mechanical deformation imparted to the sample and the detection of the resulting displacement using optical coherence tomography (OCT). We present a multiphysics model of these processes, validated by simulating strain elastograms acquired using phase-sensitive compression OCE, and demonstrating close correspondence with experimental results. Using the model, we present evidence that the approximation commonly used to infer sample displacement in phase-sensitive OCE is invalidated for smaller deformations than has been previously considered, significantly affecting the measurement precision, as quantified by the displacement sensitivity and the elastogram signal-to-noise ratio. We show how the precision of OCE is affected not only by OCT shot-noise, as is usually considered, but additionally by phase decorrelation due to the sample deformation. This multiphysics model provides a general framework that could be used to compare and contrast different OCE techniques.
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Affiliation(s)
- Lixin Chin
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, Crawley, Australia
- These authors contributed equally to this work
| | - Andrea Curatolo
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, Crawley, Australia
- These authors contributed equally to this work
| | - Brendan F. Kennedy
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, Crawley, Australia
| | - Barry J. Doyle
- Vascular Engineering, Intelligent Systems for Medicine Laboratory, School of Mechanical & Chemical Engineering, The University of Western Australia, Crawley, Australia
- Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK
| | - Peter R. T. Munro
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, Crawley, Australia
- Centre for Microscopy, Characterisation & Analysis, The University of Western Australia, Crawley, Australia
| | - Robert A. McLaughlin
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, Crawley, Australia
| | - David D. Sampson
- Optical + Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, Crawley, Australia
- Centre for Microscopy, Characterisation & Analysis, The University of Western Australia, Crawley, Australia
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Twa MD, Li J, Vantipalli S, Singh M, Aglyamov S, Emelianov S, Larin KV. Spatial characterization of corneal biomechanical properties with optical coherence elastography after UV cross-linking. BIOMEDICAL OPTICS EXPRESS 2014; 5:1419-27. [PMID: 24877005 PMCID: PMC4026912 DOI: 10.1364/boe.5.001419] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 03/28/2014] [Accepted: 03/31/2014] [Indexed: 05/18/2023]
Abstract
Corneal collagen cross-linking (CXL) is a clinical treatment for keratoconus that structurally reinforces degenerating ocular tissue, thereby limiting disease progression. Clinical outcomes would benefit from noninvasive methods to assess tissue material properties in affected individuals. Regional variations in tissue properties were quantified before and after CXL in rabbit eyes using optical coherence elastography (OCE) imaging. Low-amplitude (<1µm) elastic waves were generated using micro air-pulse stimulation and the resulting wave amplitude and speed were measured using phase-stabilized swept-source OCE. OCE imaging following CXL treatment demonstrates increased corneal stiffness through faster elastic wave propagation speeds and lower wave amplitudes.
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Affiliation(s)
- Michael D. Twa
- University of Houston, College of Optometry, 505 J. Davis Armistead Building, Houston, Texas 77204-2020, USA
- University of Houston, Department of Biomedical Engineering, 4800 Calhoun Road, Houston, Texas 77004, USA
| | - Jiasong Li
- University of Houston, Department of Biomedical Engineering, 4800 Calhoun Road, Houston, Texas 77004, USA
| | - Srilatha Vantipalli
- University of Houston, College of Optometry, 505 J. Davis Armistead Building, Houston, Texas 77204-2020, USA
| | - Manmohan Singh
- University of Houston, Department of Biomedical Engineering, 4800 Calhoun Road, Houston, Texas 77004, USA
| | - Salavat Aglyamov
- The University of Texas at Austin, Department of Biomedical Engineering, 107 W. Dean Keeton Street Stop C0800, Austin, Texas 78712, USA
| | - Stanislav Emelianov
- The University of Texas at Austin, Department of Biomedical Engineering, 107 W. Dean Keeton Street Stop C0800, Austin, Texas 78712, USA
| | - Kirill V. Larin
- University of Houston, Department of Biomedical Engineering, 4800 Calhoun Road, Houston, Texas 77004, USA
- Baylor College of Medicine, Department of Molecular Physiology and Biophysics, One Baylor Plaza, Houston, Texas 77030, USA
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Razani M, Luk TW, Mariampillai A, Siegler P, Kiehl TR, Kolios MC, Yang VX. Optical coherence tomography detection of shear wave propagation in inhomogeneous tissue equivalent phantoms and ex-vivo carotid artery samples. BIOMEDICAL OPTICS EXPRESS 2014; 5:895-906. [PMID: 24688822 PMCID: PMC3959849 DOI: 10.1364/boe.5.000895] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 01/16/2014] [Accepted: 02/19/2014] [Indexed: 05/04/2023]
Abstract
In this work, we explored the potential of measuring shear wave propagation using optical coherence elastography (OCE) in an inhomogeneous phantom and carotid artery samples based on a swept-source optical coherence tomography (OCT) system. Shear waves were generated using a piezoelectric transducer transmitting sine-wave bursts of 400 μs duration, applying acoustic radiation force (ARF) to inhomogeneous phantoms and carotid artery samples, synchronized with a swept-source OCT (SS-OCT) imaging system. The phantoms were composed of gelatin and titanium dioxide whereas the carotid artery samples were embedded in gel. Differential OCT phase maps, measured with and without the ARF, detected the microscopic displacement generated by shear wave propagation in these phantoms and samples of different stiffness. We present the technique for calculating tissue mechanical properties by propagating shear waves in inhomogeneous tissue equivalent phantoms and carotid artery samples using the ARF of an ultrasound transducer, and measuring the shear wave speed and its associated properties in the different layers with OCT phase maps. This method lays the foundation for future in-vitro and in-vivo studies of mechanical property measurements of biological tissues such as vascular tissues, where normal and pathological structures may exhibit significant contrast in the shear modulus.
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Affiliation(s)
- Marjan Razani
- Department of Physics, Ryerson University, Toronto, Canada
| | - Timothy W.H. Luk
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Canada
| | - Adrian Mariampillai
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Canada
| | - Peter Siegler
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Canada
| | - Tim-Rasmus Kiehl
- Department of Pathology, University Health Network, Toronto, Ontario Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, Canada
| | | | - Victor X.D. Yang
- Department of Physics, Ryerson University, Toronto, Canada
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Canada
- Division of Neurosurgery, University of Toronto, Toronto, Canada
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