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Lee KS, Ravichandran NK, Yeo WJ, Hur H, Hyun S, Bae JY, Kim DU, Jong Kim I, Nam KH, Bog MG, Chang KS, Kim GH. Spectrally encoded dual-mode interferometry with orthogonal scanning. OPTICS EXPRESS 2023; 31:10500-10511. [PMID: 37157595 DOI: 10.1364/oe.480261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Spectrally encoded confocal microscopy (SECM) is a high-speed reflectance confocal microscopy technique. Here, we present a method to integrate optical coherence tomography (OCT) and SECM for complementary imaging by adding orthogonal scanning to the SECM configuration. The co-registration of SECM and OCT is automatic, as all system components are shared in the same order, eliminating the need for additional optical alignment. The proposed multimode imaging system is compact and cost-effective while providing the benefits of imaging aiming and guidance. Furthermore, speckle noise can be suppressed by averaging the speckles generated by shifting the spectral-encoded field in the direction of dispersion. Using a near infrared (NIR) card and a biological sample, we demonstrated the capability of the proposed system by showing SECM imaging at depths of interest guided by the OCT in real time and speckle noise reduction. Interfaced multimodal imaging of SECM and OCT was implemented at a speed of approximately 7 frames/s using fast-switching technology and GPU processing.
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2
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Fridman L, Yelin D. Measuring the red blood cell shape in capillary flow using spectrally encoded flow cytometry. BIOMEDICAL OPTICS EXPRESS 2022; 13:4583-4591. [PMID: 36187245 PMCID: PMC9484409 DOI: 10.1364/boe.464875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 06/30/2022] [Accepted: 07/06/2022] [Indexed: 05/31/2023]
Abstract
Red blood cells in small capillaries exhibit a wide variety of deformations that reflect their true physiological conditions at these important locations. By applying a technique for the high-speed microscopy of flowing cells, termed spectrally encoded flow cytometry (SEFC), we image the light reflected from the red blood cells in human capillaries, and propose an analytical slipper-like model for the cell morphology that can reproduce the experimental in vivo images. The results of this work would be useful for studying the unique flow conditions in these vessels, and for extracting useful clinical parameters that reflect the true physiology of the blood cells in situ.
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3
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Wang Y, Warter A, Cavichini-Cordeiro M, Freeman WR, Bartsch DUG, Nguyen TQ, An C. LEARNING TO CORRECT AXIAL MOTION IN OCT FOR 3D RETINAL IMAGING. PROCEEDINGS. INTERNATIONAL CONFERENCE ON IMAGE PROCESSING 2021; 2021:126-130. [PMID: 35950046 PMCID: PMC9359411 DOI: 10.1109/icip42928.2021.9506620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Optical Coherence Tomography (OCT) is a powerful technique for non-invasive 3D imaging of biological tissues at high resolution that has revolutionized retinal imaging. A major challenge in OCT imaging is the motion artifacts introduced by involuntary eye movements. In this paper, we propose a convolutional neural network that learns to correct axial motion in OCT based on a single volumetric scan. The proposed method is able to correct large motion, while preserving the overall curvature of the retina. The experimental results show significant improvements in visual quality as well as overall error compared to the conventional methods in both normal and disease cases.
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Affiliation(s)
- Yiqian Wang
- Department of Electrical and Computer Engineering, University of California, San Diego
| | - Alexandra Warter
- Jacobs Retina Center, Shiley Eye Institute, La Jolla, California, USA
| | | | - William R Freeman
- Jacobs Retina Center, Shiley Eye Institute, La Jolla, California, USA
| | | | - Truong Q Nguyen
- Department of Electrical and Computer Engineering, University of California, San Diego
| | - Cheolhong An
- Department of Electrical and Computer Engineering, University of California, San Diego
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4
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Ringel MJ, Tang EM, Tao YK. Advances in multimodal imaging in ophthalmology. Ther Adv Ophthalmol 2021; 13:25158414211002400. [PMID: 35187398 PMCID: PMC8855415 DOI: 10.1177/25158414211002400] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 02/23/2021] [Indexed: 12/12/2022] Open
Abstract
Multimodality ophthalmic imaging systems aim to enhance the contrast, resolution, and functionality of existing technologies to improve disease diagnostics and therapeutic guidance. These systems include advanced acquisition and post-processing methods using optical coherence tomography (OCT), combined scanning laser ophthalmoscopy and OCT systems, adaptive optics, surgical guidance, and photoacoustic technologies. Here, we provide an overview of these ophthalmic imaging systems and their clinical and basic science applications.
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Affiliation(s)
- Morgan J. Ringel
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Eric M. Tang
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Yuankai K. Tao
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
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5
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Makita S, Miura M, Azuma S, Mino T, Yamaguchi T, Yasuno Y. Accurately motion-corrected Lissajous OCT with multi-type image registration. BIOMEDICAL OPTICS EXPRESS 2021; 12:637-653. [PMID: 33659092 PMCID: PMC7899516 DOI: 10.1364/boe.409004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 12/02/2020] [Accepted: 12/15/2020] [Indexed: 05/06/2023]
Abstract
Passive motion correction methods for optical coherence tomography (OCT) use image registration to estimate eye movements. To improve motion correction, a multi-image cross-correlation that employs spatial features in different image types is introduced. Lateral motion correction using en face OCT and OCT-A projections on Lissajous-scanned OCT data is applied. Motion correction using OCT-A projection of whole depth and OCT amplitude, OCT logarithmic intensity, and OCT maximum intensity projections were evaluated in retinal imaging with 76 patients. The proposed method was compared with motion correction using OCT-A projection of whole depth. The comparison shows improvements in the image quality of motion-corrected superficial OCT-A images and image registration.
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Affiliation(s)
- Shuichi Makita
- Computation Optics Group, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan
- Computational Optics and Ophthalmology Group, Ibaraki, Japan
| | - Masahiro Miura
- Computational Optics and Ophthalmology Group, Ibaraki, Japan
- Department of Ophthalmology, Tokyo Medical University Ibaraki Medical Center, 3-20-1 Chuo, Ami, Ibaraki 300-0395, Japan
| | - Shinnosuke Azuma
- Topcon Corporation, 75-1 Hasunumacho, Itabashi, Tokyo 174-8580, Japan
| | - Toshihiro Mino
- Topcon Corporation, 75-1 Hasunumacho, Itabashi, Tokyo 174-8580, Japan
| | - Tatsuo Yamaguchi
- Topcon Corporation, 75-1 Hasunumacho, Itabashi, Tokyo 174-8580, Japan
| | - Yoshiaki Yasuno
- Computation Optics Group, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan
- Computational Optics and Ophthalmology Group, Ibaraki, Japan
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6
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Malone JD, El-Haddad MT, Yerramreddy SS, Oguz I, Tao YK. Handheld spectrally encoded coherence tomography and reflectometry for motion-corrected ophthalmic optical coherence tomography and optical coherence tomography angiography. NEUROPHOTONICS 2019; 6:041102. [PMID: 32042852 PMCID: PMC6991137 DOI: 10.1117/1.nph.6.4.041102] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 06/12/2019] [Indexed: 05/05/2023]
Abstract
Optical coherence tomography (OCT) is the gold standard for quantitative ophthalmic imaging. The majority of commercial and research systems require patients to fixate and be imaged in a seated upright position, which limits the ability to perform ophthalmic imaging in bedridden or pediatric patients. Handheld OCT devices overcome this limitation, but image quality often suffers due to a lack of real-time aiming and patient eye and photographer motion. We describe a handheld spectrally encoded coherence tomography and reflectometry (SECTR) system that enables simultaneous en face reflectance and cross-sectional OCT imaging. The handheld probe utilizes a custom double-pass scan lens for fully telecentric OCT scanning with a compact optomechanical design and a rapid-prototyped enclosure to reduce the overall system size and weight. We also introduce a variable velocity scan waveform that allows for simultaneous acquisition of densely sampled OCT angiography (OCTA) volumes and widefield reflectance images, which enables high-resolution vascular imaging with precision motion-tracking for volumetric motion correction and multivolumetric mosaicking. Finally, we demonstrate in vivo human retinal OCT and OCT angiography (OCTA) imaging using handheld SECTR on a healthy volunteer. Clinical translation of handheld SECTR will allow for high-speed, motion-corrected widefield OCT and OCTA imaging in bedridden and pediatric patients who may benefit ophthalmic disease diagnosis and monitoring.
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Affiliation(s)
- Joseph D. Malone
- Vanderbilt University, Department of Biomedical Engineering, Nashville, Tennessee, United States
| | - Mohamed T. El-Haddad
- Vanderbilt University, Department of Biomedical Engineering, Nashville, Tennessee, United States
| | - Suhaas S. Yerramreddy
- Vanderbilt University, Department of Electrical Engineering and Computer Science, Nashville, Tennessee, United States
| | - Ipek Oguz
- Vanderbilt University, Department of Electrical Engineering and Computer Science, Nashville, Tennessee, United States
| | - Yuankai K. Tao
- Vanderbilt University, Department of Biomedical Engineering, Nashville, Tennessee, United States
- Address all correspondence to Yuankai K. Tao, E-mail:
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7
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El-Haddad MT, Bozic I, Tao YK. Spectrally encoded coherence tomography and reflectometry: Simultaneous en face and cross-sectional imaging at 2 gigapixels per second. JOURNAL OF BIOPHOTONICS 2018; 11:e201700268. [PMID: 29149542 PMCID: PMC5903931 DOI: 10.1002/jbio.201700268] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/10/2017] [Indexed: 05/18/2023]
Abstract
Non-invasive biological imaging is crucial for understanding in vivo structure and function. Optical coherence tomography (OCT) and reflectance confocal microscopy are two of the most widely used optical modalities for exogenous contrast-free, high-resolution, three-dimensional imaging in non-fluorescent scattering tissues. However, sample motion remains a critical barrier to raster-scanned acquisition and reconstruction of wide-field anatomically accurate volumetric datasets. We introduce spectrally encoded coherence tomography and reflectometry (SECTR), a high-speed, multimodality system for simultaneous OCT and spectrally encoded reflectance (SER) imaging. SECTR utilizes a robust system design consisting of shared optical relays, scanning mirrors, swept laser and digitizer to achieve the fastest reported in vivo multimodal imaging rate of 2 gigapixels per second. Our optical design and acquisition scheme enable spatiotemporally co-registered acquisition of OCT cross-sections simultaneously with en face SER images for multivolumetric mosaicking. Complementary axial and lateral translation and rotation are extracted from OCT and SER data, respectively, for full volumetric estimation of sample motion with micron spatial and millisecond temporal resolution.
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Affiliation(s)
- Mohamed T. El-Haddad
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Ivan Bozic
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Yuankai K. Tao
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
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8
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El-Haddad MT, Bozic I, Tao YK. Spectrally encoded coherence tomography and reflectometry: Simultaneous en face and cross-sectional imaging at 2 gigapixels per second. JOURNAL OF BIOPHOTONICS 2018; 11:e201700268. [PMID: 29149542 DOI: 10.1002/jbio.2018.11.issue-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/10/2017] [Indexed: 05/22/2023]
Abstract
Non-invasive biological imaging is crucial for understanding in vivo structure and function. Optical coherence tomography (OCT) and reflectance confocal microscopy are two of the most widely used optical modalities for exogenous contrast-free, high-resolution, three-dimensional imaging in non-fluorescent scattering tissues. However, sample motion remains a critical barrier to raster-scanned acquisition and reconstruction of wide-field anatomically accurate volumetric datasets. We introduce spectrally encoded coherence tomography and reflectometry (SECTR), a high-speed, multimodality system for simultaneous OCT and spectrally encoded reflectance (SER) imaging. SECTR utilizes a robust system design consisting of shared optical relays, scanning mirrors, swept laser and digitizer to achieve the fastest reported in vivo multimodal imaging rate of 2 gigapixels per second. Our optical design and acquisition scheme enable spatiotemporally co-registered acquisition of OCT cross-sections simultaneously with en face SER images for multivolumetric mosaicking. Complementary axial and lateral translation and rotation are extracted from OCT and SER data, respectively, for full volumetric estimation of sample motion with micron spatial and millisecond temporal resolution.
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Affiliation(s)
- Mohamed T El-Haddad
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
| | - Ivan Bozic
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
| | - Yuankai K Tao
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
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9
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Baghaie A, Yu Z, D'Souza RM. Involuntary eye motion correction in retinal optical coherence tomography: Hardware or software solution? Med Image Anal 2017; 37:129-145. [PMID: 28208100 DOI: 10.1016/j.media.2017.02.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Revised: 01/27/2017] [Accepted: 02/03/2017] [Indexed: 01/05/2023]
Abstract
In this paper, we review state-of-the-art techniques to correct eye motion artifacts in Optical Coherence Tomography (OCT) imaging. The methods for eye motion artifact reduction can be categorized into two major classes: (1) hardware-based techniques and (2) software-based techniques. In the first class, additional hardware is mounted onto the OCT scanner to gather information about the eye motion patterns during OCT data acquisition. This information is later processed and applied to the OCT data for creating an anatomically correct representation of the retina, either in an offline or online manner. In software based techniques, the motion patterns are approximated either by comparing the acquired data to a reference image, or by considering some prior assumptions about the nature of the eye motion. Careful investigations done on the most common methods in the field provides invaluable insight regarding future directions of the research in this area. The challenge in hardware-based techniques lies in the implementation aspects of particular devices. However, the results of these techniques are superior to those obtained from software-based techniques because they are capable of capturing secondary data related to eye motion during OCT acquisition. Software-based techniques on the other hand, achieve moderate success and their performance is highly dependent on the quality of the OCT data in terms of the amount of motion artifacts contained in them. However, they are still relevant to the field since they are the sole class of techniques with the ability to be applied to legacy data acquired using systems that do not have extra hardware to track eye motion.
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Affiliation(s)
- Ahmadreza Baghaie
- Department of Electrical Engineering, University of Wisconsin-Milwaukee, WI 53211, USA.
| | - Zeyun Yu
- Department of Computer Science, University of Wisconsin-Milwaukee, WI 53211, USA
| | - Roshan M D'Souza
- Department of Mechanical Engineering, University of Wisconsin-Milwaukee, WI 53211, USA
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10
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Malone JD, El-Haddad MT, Bozic I, Tye LA, Majeau L, Godbout N, Rollins AM, Boudoux C, Joos KM, Patel SN, Tao YK. Simultaneous multimodal ophthalmic imaging using swept-source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2017; 8:193-206. [PMID: 28101411 PMCID: PMC5231292 DOI: 10.1364/boe.8.000193] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 12/06/2016] [Accepted: 12/07/2016] [Indexed: 05/18/2023]
Abstract
Scanning laser ophthalmoscopy (SLO) benefits diagnostic imaging and therapeutic guidance by allowing for high-speed en face imaging of retinal structures. When combined with optical coherence tomography (OCT), SLO enables real-time aiming and retinal tracking and provides complementary information for post-acquisition volumetric co-registration, bulk motion compensation, and averaging. However, multimodality SLO-OCT systems generally require dedicated light sources, scanners, relay optics, detectors, and additional digitization and synchronization electronics, which increase system complexity. Here, we present a multimodal ophthalmic imaging system using swept-source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography (SS-SESLO-OCT) for in vivo human retinal imaging. SESLO reduces the complexity of en face imaging systems by multiplexing spatial positions as a function of wavelength. SESLO image quality benefited from single-mode illumination and multimode collection through a prototype double-clad fiber coupler, which optimized scattered light throughput and reduce speckle contrast while maintaining lateral resolution. Using a shared 1060 nm swept-source, shared scanner and imaging optics, and a shared dual-channel high-speed digitizer, we acquired inherently co-registered en face retinal images and OCT cross-sections simultaneously at 200 frames-per-second.
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Affiliation(s)
- Joseph D. Malone
- Current Affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
- Previous Affiliation: Ophthalmic Imaging Center, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Mohamed T. El-Haddad
- Current Affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
- Previous Affiliation: Ophthalmic Imaging Center, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Ivan Bozic
- Current Affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
- Previous Affiliation: Ophthalmic Imaging Center, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Logan A. Tye
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | | | - Nicolas Godbout
- Castor Optics, Montreal, QC H3T 2B1, Canada
- Centre d’Optique Photonique et Lasers, Polytechnique Montreal, Department of Engineering Physics, Montreal, QC H3C 3A7, Canada
| | - Andrew M. Rollins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Caroline Boudoux
- Castor Optics, Montreal, QC H3T 2B1, Canada
- Centre d’Optique Photonique et Lasers, Polytechnique Montreal, Department of Engineering Physics, Montreal, QC H3C 3A7, Canada
| | - Karen M. Joos
- Current Affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
- Department of Ophthalmology and Visual Sciences, Vanderbilt University, Nashville, TN 37235, USA
| | - Shriji N. Patel
- Department of Ophthalmology and Visual Sciences, Vanderbilt University, Nashville, TN 37235, USA
| | - Yuankai K. Tao
- Current Affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
- Previous Affiliation: Ophthalmic Imaging Center, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA
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11
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LaRocca F, Nankivil D, Farsiu S, Izatt JA. True color scanning laser ophthalmoscopy and optical coherence tomography handheld probe. BIOMEDICAL OPTICS EXPRESS 2014; 5:3204-16. [PMID: 25401032 PMCID: PMC4230880 DOI: 10.1364/boe.5.003204] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 08/20/2014] [Accepted: 08/21/2014] [Indexed: 05/20/2023]
Abstract
Scanning laser ophthalmoscopes (SLOs) are able to achieve superior contrast and axial sectioning capability compared to fundus photography. However, SLOs typically use monochromatic illumination and are thus unable to extract color information of the retina. Previous color SLO imaging techniques utilized multiple lasers or narrow band sources for illumination, which allowed for multiple color but not "true color" imaging as done in fundus photography. We describe the first "true color" SLO, handheld color SLO, and combined color SLO integrated with a spectral domain optical coherence tomography (OCT) system. To achieve accurate color imaging, the SLO was calibrated with a color test target and utilized an achromatizing lens when imaging the retina to correct for the eye's longitudinal chromatic aberration. Color SLO and OCT images from volunteers were then acquired simultaneously with a combined power under the ANSI limit. Images from this system were then compared with those from commercially available SLOs featuring multiple narrow-band color imaging.
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Affiliation(s)
- Francesco LaRocca
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Derek Nankivil
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Sina Farsiu
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Joseph A. Izatt
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, 27710, USA
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12
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Marques MJ, Bradu A, Podoleanu AG. Towards simultaneous Talbot bands based optical coherence tomography and scanning laser ophthalmoscopy imaging. BIOMEDICAL OPTICS EXPRESS 2014; 5:1428-1444. [PMID: 24877006 PMCID: PMC4026900 DOI: 10.1364/boe.5.001428] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 03/31/2014] [Accepted: 04/01/2014] [Indexed: 05/29/2023]
Abstract
We report a Talbot bands-based optical coherence tomography (OCT) system capable of producing longitudinal B-scan OCT images and en-face scanning laser ophthalmoscopy (SLO) images of the human retina in-vivo. The OCT channel employs a broadband optical source and a spectrometer. A gap is created between the sample and reference beams while on their way towards the spectrometer's dispersive element to create Talbot bands. The spatial separation of the two beams facilitates collection by an SLO channel of optical power originating exclusively from the retina, deprived from any contribution from the reference beam. Three different modes of operation are presented, constrained by the minimum integration time of the camera used in the spectrometer and by the galvo-scanners' scanning rate: (i) a simultaneous acquisition mode over the two channels, useful for small size imaging, that conserves the pixel-to-pixel correspondence between them; (ii) a hybrid sequential mode, where the system switches itself between the two regimes and (iii) a sequential "on-demand" mode, where the system can be used in either OCT or SLO regimes for as long as required. The two sequential modes present varying degrees of trade-off between pixel-to-pixel correspondence and independent full control of parameters within each channel. Images of the optic nerve and fovea regions obtained in the simultaneous (i) and in the hybrid sequential mode (ii) are presented.
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13
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LaRocca F, Dhalla AH, Kelly MP, Farsiu S, Izatt JA. Optimization of confocal scanning laser ophthalmoscope design. JOURNAL OF BIOMEDICAL OPTICS 2013; 18:076015. [PMID: 23864013 PMCID: PMC3713285 DOI: 10.1117/1.jbo.18.7.076015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 06/15/2013] [Accepted: 06/17/2013] [Indexed: 05/20/2023]
Abstract
Confocal scanning laser ophthalmoscopy (cSLO) enables high-resolution and high-contrast imaging of the retina by employing spatial filtering for scattered light rejection. However, to obtain optimized image quality, one must design the cSLO around scanner technology limitations and minimize the effects of ocular aberrations and imaging artifacts. We describe a cSLO design methodology resulting in a simple, relatively inexpensive, and compact lens-based cSLO design optimized to balance resolution and throughput for a 20-deg field of view (FOV) with minimal imaging artifacts. We tested the imaging capabilities of our cSLO design with an experimental setup from which we obtained fast and high signal-to-noise ratio (SNR) retinal images. At lower FOVs, we were able to visualize parafoveal cone photoreceptors and nerve fiber bundles even without the use of adaptive optics. Through an experiment comparing our optimized cSLO design to a commercial cSLO system, we show that our design demonstrates a significant improvement in both image quality and resolution.
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Affiliation(s)
- Francesco LaRocca
- Duke University, Department of Biomedical Engineering, Durham, North Carolina 27708, USA.
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14
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Visualization of real-time intraoperative maneuvers with a microscope-mounted spectral domain optical coherence tomography system. Retina 2013. [PMID: 23190928 DOI: 10.1097/iae.0b013e31826e86f5] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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15
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LaRocca F, Nankivil D, Farsiu S, Izatt JA. Handheld simultaneous scanning laser ophthalmoscopy and optical coherence tomography system. BIOMEDICAL OPTICS EXPRESS 2013; 4:2307-21. [PMID: 24298396 PMCID: PMC3829529 DOI: 10.1364/boe.4.002307] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 09/24/2013] [Accepted: 09/25/2013] [Indexed: 05/03/2023]
Abstract
Scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) are widely used retinal imaging modalities that can assist in the diagnosis of retinal pathologies. The combination of SLO and OCT provides a more comprehensive imaging system and a method to register OCT images to produce motion corrected retinal volumes. While high quality, bench-top SLO-OCT systems have been discussed in the literature and are available commercially, there are currently no handheld designs. We describe the first design and fabrication of a handheld SLO/spectral domain OCT probe. SLO and OCT images were acquired simultaneously with a combined power under the ANSI limit. High signal-to-noise ratio SLO and OCT images were acquired simultaneously from a normal subject with visible motion artifacts. Fully automated motion estimation methods were performed in post-processing to correct for the inter- and intra-frame motion in SLO images and their concurrently acquired OCT volumes. The resulting set of reconstructed SLO images and the OCT volume were without visible motion artifacts. At a reduced field of view, the SLO resolved parafoveal cones without adaptive optics at a retinal eccentricity of 11° in subjects with good ocular optics. This system may be especially useful for imaging young children and subjects with less stable fixation.
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Affiliation(s)
- Francesco LaRocca
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Derek Nankivil
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Sina Farsiu
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Joseph A. Izatt
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, 27710, USA
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16
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Klein T, Wieser W, Reznicek L, Neubauer A, Kampik A, Huber R. Multi-MHz retinal OCT. BIOMEDICAL OPTICS EXPRESS 2013; 4:1890-908. [PMID: 24156052 PMCID: PMC3799654 DOI: 10.1364/boe.4.001890] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 07/17/2013] [Accepted: 07/18/2013] [Indexed: 05/17/2023]
Abstract
We analyze the benefits and problems of in vivo optical coherence tomography (OCT) imaging of the human retina at A-scan rates in excess of 1 MHz, using a 1050 nm Fourier-domain mode-locked (FDML) laser. Different scanning strategies enabled by MHz OCT line rates are investigated, and a simple multi-volume data processing approach is presented. In-vivo OCT of the human ocular fundus is performed at different axial scan rates of up to 6.7 MHz. High quality non-mydriatic retinal imaging over an ultra-wide field is achieved by a combination of several key improvements compared to previous setups. For the FDML laser, long coherence lengths and 72 nm wavelength tuning range are achieved using a chirped fiber Bragg grating in a laser cavity at 419.1 kHz fundamental tuning rate. Very large data sets can be acquired with sustained data transfer from the data acquisition card to host computer memory, enabling high-quality averaging of many frames and of multiple aligned data sets. Three imaging modes are investigated: Alignment and averaging of 24 data sets at 1.68 MHz axial line rate, ultra-dense transverse sampling at 3.35 MHz line rate, and dual-beam imaging with two laser spots on the retina at an effective line rate of 6.7 MHz.
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Affiliation(s)
- Thomas Klein
- Lehrstuhl für BioMolekulare Optik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Oettingenstr. 67, 80538 Munich, Germany
| | - Wolfgang Wieser
- Lehrstuhl für BioMolekulare Optik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Oettingenstr. 67, 80538 Munich, Germany
| | - Lukas Reznicek
- Augenklinik der Ludwig-Maximilians-Universität München, Mathildenstraße 8, 80336 Munich, Germany
| | - Aljoscha Neubauer
- Augenklinik der Ludwig-Maximilians-Universität München, Mathildenstraße 8, 80336 Munich, Germany
| | - Anselm Kampik
- Augenklinik der Ludwig-Maximilians-Universität München, Mathildenstraße 8, 80336 Munich, Germany
| | - Robert Huber
- Lehrstuhl für BioMolekulare Optik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Oettingenstr. 67, 80538 Munich, Germany
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17
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Estrada R, Tomasi C, Cabrera MT, Wallace DK, Freedman SF, Farsiu S. Enhanced video indirect ophthalmoscopy (VIO) via robust mosaicing. BIOMEDICAL OPTICS EXPRESS 2011; 2:2871-87. [PMID: 22091442 PMCID: PMC3191451 DOI: 10.1364/boe.2.002871] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 09/16/2011] [Accepted: 09/17/2011] [Indexed: 05/19/2023]
Abstract
Indirect ophthalmoscopy (IO) is the standard of care for evaluation of the neonatal retina. When recorded on video from a head-mounted camera, IO images have low quality and narrow Field of View (FOV). We present an image fusion methodology for converting a video IO recording into a single, high quality, wide-FOV mosaic that seamlessly blends the best frames in the video. To this end, we have developed fast and robust algorithms for automatic evaluation of video quality, artifact detection and removal, vessel mapping, registration, and multi-frame image fusion. Our experiments show the effectiveness of the proposed methods.
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Affiliation(s)
- Rolando Estrada
- Dept. of Computer Science, Duke University, Durham, NC 27708
| | - Carlo Tomasi
- Dept. of Computer Science, Duke University, Durham, NC 27708
| | | | | | | | - Sina Farsiu
- Dept. of Ophthalmology, Duke University, Durham, NC 27708
- Dept. of Biomedical Engineering, Duke University, Durham, NC 27708
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