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Di Pippo M, Santia C, Rullo D, Ciancimino C, Grassi F, Abdolrahimzadeh S. The Choroidal Vascularity Index Versus Optical Coherence Tomography Angiography in the Evaluation of the Choroid with a Focus on Age-Related Macular Degeneration. Tomography 2023; 9:1456-1470. [PMID: 37624109 PMCID: PMC10458084 DOI: 10.3390/tomography9040116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 07/31/2023] [Accepted: 08/02/2023] [Indexed: 08/26/2023] Open
Abstract
The choroid is the most vascularized structure of the eye and it is fundamental for the trophism of the outer retina. Its proper functioning and homeostasis represent key points in maintaining normal retinal physiology. Choroidal alterations may be implicated in the development and progression of numerous pathologies; therefore, in-depth studies using imaging techniques can be of crucial relevance to understanding the pathophysiology of retinal-choroidal diseases. The advent of spectral-domain optical coherence tomography (SDOCT) has enabled the non-invasive study of the choroid in vivo and the most recent development, optical coherence tomography angiography (OCTA), allows for the high-resolution visualization of the choriocapillaris and the choroid in regard to vascularization. The choroidal vascularity index (CVI) is a new parameter calculated on SDOCT scans and is defined as the ratio of the luminal area to the total choroidal area. In this review, a study of the choroid using OCTA and CVI will be evaluated in depth and the pros and cons of these two methods will be analyzed, with a particular focus on age-related macular degeneration.
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Affiliation(s)
| | | | | | | | | | - Solmaz Abdolrahimzadeh
- Ophthalmology Unit, Neurosciences, Mental Health, and Sense Organs (NESMOS) Department, Faculty of Medicine and Psychology, University of Rome Sapienza, St. Andrea Hospital, 00189 Rome, Italy; (M.D.P.); (C.C.)
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Abdolrahimzadeh S, Di Pippo M, Sordi E, Cusato M, Lotery AJ. Subretinal drusenoid deposits as a biomarker of age-related macular degeneration progression via reduction of the choroidal vascularity index. Eye (Lond) 2023; 37:1365-1370. [PMID: 35739243 PMCID: PMC10169760 DOI: 10.1038/s41433-022-02134-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 05/09/2022] [Accepted: 06/09/2022] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND/OBJECTIVES This study aimed to analyse the role of the choroid in early age-related macular degeneration (AMD) by analysing choroidal vascularity index (CVI) in pure cohorts of patients with subretinal drusenoid deposits (SDD) or conventional drusen (CD). SUBJECTS/METHODS This was an observational cross-sectional study. Comprehensive ophthalmologic examination and multimodal imaging including fundus photography, autofluorescence, near infrared reflectance, and spectral domain optical coherence tomography (SDOCT) was performed. CVI processing was performed on a foveal horizontal SDOCT scan with binarization using Image J Image software and calculated as the ratio between luminal area (LA) and total area (TA). RESULTS Sixty-nine eyes of 69 participants were included; 23 eyes with SDD alone, 22 eyes with CD alone, and 24 control eyes of healthy age-matched subjects. CVI was significantly reduced in the SDD and CD group compared to controls (p = 0.0001). Post-hoc analysis revealed a significant reduction of CVI in the SDD versus the control group (p = 0.0002), in the CD versus the control group (p = 0.001), and in the SDD versus the CD group (p = 0.006). Covariance analysis showed a significant difference of LA (p = 0.033) but no significant difference of TA (p = 0.106) between the three groups. Direct comparison between CD and SDD showed a significant reduction of LA and TA in the SDD group. CONCLUSIONS CVI may have prognostic implications in early AMD. SDD is a biomarker of AMD progression and the mechanism for this could be via reduction of the CVI.
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Affiliation(s)
- Solmaz Abdolrahimzadeh
- Ophthalmology Unit, Neurosciences, Mental Health, and Sense Organs (NESMOS) Department, Faculty of Medicine and Psychology, University of Rome Sapienza, Rome, Italy.
- St. Andrea Hospita, Via di Grottarossa 1035/1039, Rome, 00189, Italy.
| | - Mariachiara Di Pippo
- Ophthalmology Unit, Neurosciences, Mental Health, and Sense Organs (NESMOS) Department, Faculty of Medicine and Psychology, University of Rome Sapienza, Rome, Italy
| | - Edoardo Sordi
- Ophthalmology Unit, Neurosciences, Mental Health, and Sense Organs (NESMOS) Department, Faculty of Medicine and Psychology, University of Rome Sapienza, Rome, Italy
| | - Mattia Cusato
- Ophthalmology Unit, Neurosciences, Mental Health, and Sense Organs (NESMOS) Department, Faculty of Medicine and Psychology, University of Rome Sapienza, Rome, Italy
| | - Andrew John Lotery
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, SO16 6YD, UK
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Arrigo A, Teussink M, Bianco L, Antropoli A, Aragona E, Cappuccio G, Bandello F, Parodi MB. High-resolution/High-Speed Gap Can Distinguish Different Intraretinal Perfusion Signals by Optical Coherence Tomography Angiography. Transl Vis Sci Technol 2023; 12:11. [PMID: 37163285 PMCID: PMC10179578 DOI: 10.1167/tvst.12.5.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023] Open
Abstract
Purpose The development of optical coherence tomography angiography (OCTA) has radically changed the diagnostic assessment of the intraretinal vascular network. Two different OCTA acquisition modalities have recently been introduced in clinical practice, namely high-resolution (HR) and high-speed (HS) scans. HR OCTA requires more acquisition time and provides higher quality data, whereas HS OCTA is faster but furnishes lower quality data. The main aim of the present study is to gauge how much extra blood flow perfusion information can be obtained through the combined use of HR and HS OCTA. Methods We compared HR and HS OCTA acquisitions to assess the reliability of both techniques, also putting forward a new set of quantitative metrics to measure the HR/HS OCTA gap and to highlight different perfusion information. Results In essence, both HR and HS OCTA acquisitions proved highly feasible in detecting the intraretinal vascular flow signal, as confirmed by the stability of quantitative OCTA metrics, thus displaying their suitability for use in clinical practice. We detected an HR/HS overlapping gap of 21.6 ± 6.5% for intraretinal capillaries, and 4.3 ± 1.2% for choriocapillaris, highlighting the greater information obtained by HR OCTA. Conclusions This novel HR/HS OCTA gap assessment might pave the way for the development of new quantitative metrics for retinal diseases that would focus on the earlier detection of perfusion impairment and relate it to the stage of the disease and its progression. Translational Relevance This study proposes a new quantitative way to detect different perfusion signals based on OCTA. The findings presented in this paper can lay the foundations for the development of new quantitative metrics focused on the separate analysis of high flow and low flow signals, enabling very early changes in intraretinal perfusion to be detected.
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Affiliation(s)
- Alessandro Arrigo
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, via Olgettina 60, Milan, Italy
| | | | - Lorenzo Bianco
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, via Olgettina 60, Milan, Italy
| | - Alessio Antropoli
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, via Olgettina 60, Milan, Italy
| | - Emanuela Aragona
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, via Olgettina 60, Milan, Italy
| | - Giuseppe Cappuccio
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, via Olgettina 60, Milan, Italy
| | - Francesco Bandello
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, via Olgettina 60, Milan, Italy
| | - Maurizio Battaglia Parodi
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, via Olgettina 60, Milan, Italy
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Liu Z, Zhang F, Zucca K, Agrawal A, Hammer DX. Ultrahigh-speed multimodal adaptive optics system for microscopic structural and functional imaging of the human retina. BIOMEDICAL OPTICS EXPRESS 2022; 13:5860-5878. [PMID: 36733751 PMCID: PMC9872887 DOI: 10.1364/boe.462594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 09/16/2022] [Accepted: 09/20/2022] [Indexed: 05/02/2023]
Abstract
We describe the design and performance of a multimodal and multifunctional adaptive optics (AO) system that combines scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) for simultaneous retinal imaging at 13.4 Hz. The high-speed AO-OCT channel uses a 3.4 MHz Fourier-domain mode-locked (FDML) swept source. The system achieves exquisite resolution and sensitivity for pan-macular and transretinal visualization of retinal cells and structures while providing a functional assessment of the cone photoreceptors. The ultra-high speed also enables wide-field scans for clinical usability and angiography for vascular visualization. The FDA FDML-AO system is a powerful platform for studying various retinal and neurological diseases for vision science research, retina physiology investigation, and biomarker development.
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Affiliation(s)
- Zhuolin Liu
- Center for Devices and Radiological Health
(CDRH), U. S. Food and Drug Administration (FDA), Silver Spring, Maryland 20993, USA
| | - Furu Zhang
- Center for Devices and Radiological Health
(CDRH), U. S. Food and Drug Administration (FDA), Silver Spring, Maryland 20993, USA
- Co-first author
| | - Kelvy Zucca
- Center for Devices and Radiological Health
(CDRH), U. S. Food and Drug Administration (FDA), Silver Spring, Maryland 20993, USA
| | - Anant Agrawal
- Center for Devices and Radiological Health
(CDRH), U. S. Food and Drug Administration (FDA), Silver Spring, Maryland 20993, USA
| | - Daniel X. Hammer
- Center for Devices and Radiological Health
(CDRH), U. S. Food and Drug Administration (FDA), Silver Spring, Maryland 20993, USA
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Liang Y, Liu B, Xiao Y, Zeng X, Wu G, Du Z, Fang Y, Hu Y, Yang X, Yu H. Retinal Neurovascular Changes in Patients With Ischemic Stroke Investigated by Optical Coherence Tomography Angiography. Front Aging Neurosci 2022; 14:834560. [PMID: 35860669 PMCID: PMC9289443 DOI: 10.3389/fnagi.2022.834560] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 06/14/2022] [Indexed: 11/13/2022] Open
Abstract
BackgroundTo investigate retinal neurovascular structural changes in patients with ischemic stroke (IS) using optical coherence tomography angiography (OCTA).Materials and MethodsThe cross-sectional study was conducted in Guangdong Provincial People’s Hospital, China, consisting of 159 eyes from IS patients and 109 eyes from age-matched control subjects. Retinal microvascular parameters including the vessel density (VD) of the superficial capillary plexus (SCP), deep capillary plexus (DCP) and radial peripapillary capillary (RPC), and neural parameters such as ganglion cell complex thickness (GCCt) and retinal nerve fibre layer thickness (RNFLt) were measured by OCTA.ResultsThe VD of SCP and DCP in the macular area were significantly reduced in IS patients compared to the control group (all p < 0.001). The VD of RPC at the optic disc was also significantly reduced in IS patients (all p < 0.05). IS patients showed reduced GCCt and RNFLt and increased GCC focal loss volume and global loss volume compared with the controls (all p < 0.05). Among patients with IS, the parafovea SCP VD was positively correlated with GCCt (r = 0.346–0.408, all p < 0.001) but not with DCP VD (all p > 0.1). In the optic disc region, the whole image RPC VD was positively correlated with mean RNFLt (r = 0.467–0.548, all p < 0.001).ConclusionReduction of retinal VD, GCCt and RNFLt was observed in patients with IS. The parafovea SCP VD and RPC VD were positively correlated with GCCt and RNFLt, respectively.
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Affiliation(s)
- Yingying Liang
- Guangdong Eye Institute, Department of Ophthalmology, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, The Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
| | - Baoyi Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yu Xiao
- Guangdong Eye Institute, Department of Ophthalmology, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, The Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
| | - Xiaomin Zeng
- Guangdong Eye Institute, Department of Ophthalmology, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, The Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
| | - Guanrong Wu
- School of Medicine, South China University of Technology, Guangzhou, China
| | - Zijing Du
- Guangdong Eye Institute, Department of Ophthalmology, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, The Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
| | - Ying Fang
- Guangdong Eye Institute, Department of Ophthalmology, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, The Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
| | - Yijun Hu
- Guangdong Eye Institute, Department of Ophthalmology, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, The Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
- *Correspondence: Yijun Hu,
| | - Xiaohong Yang
- Guangdong Eye Institute, Department of Ophthalmology, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, The Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
- Xiaohong Yang,
| | - Honghua Yu
- Guangdong Eye Institute, Department of Ophthalmology, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, The Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
- Honghua Yu,
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Optomechanical Analysis and Design of Polygon Mirror-Based Laser Scanners. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12115592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Polygon Mirror (PM)-based scanning heads are one of the fastest and most versatile optomechanical laser scanners. The aim of this work is to develop a multi-parameter opto-mechanical analysis of PMs, from which to extract rules-of-thumbs for the design of such systems. The characteristic functions and parameters of PMs scanning heads are deduced and studied, considering their constructive and functional parameters. Optical aspects related to the kinematics of emergent laser beams (and of corresponding laser spots on a scanned plane or objective lens) are investigated. The PM analysis (which implies a larger number of parameters) is confronted with the corresponding, but less complex aspects of Galvanometer Scanners (GSs). The issue of the non-linearity of the scanning functions of both PMs and GSs (and, consequently, of their variable scanning velocities) is approached, as well as characteristic angles, the angular and linear Field-of-View (FOV), and the duty cycle. A device with two supplemental mirrors is proposed and designed to increase the distance between the GS or PM and the scanned plane or lens to linearize the scanning function (and thus to achieve an approximately constant scanning velocity). These optical aspects are completed with Finite Element Analyses (FEA) of fast rotational PMs, to assess their structural integrity issues. The study is concluded with an optomechanical design scheme of PM-based scanning heads, which unites optical and mechanical aspects—to allow for a more comprehensive approach of possible issues of such scanners. Such a scheme can be applied to other types of optomechanical scanners, with mirrors or refractive elements, as well.
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Sampson DM, Dubis AM, Chen FK, Zawadzki RJ, Sampson DD. Towards standardizing retinal optical coherence tomography angiography: a review. LIGHT, SCIENCE & APPLICATIONS 2022; 11:63. [PMID: 35304441 PMCID: PMC8933532 DOI: 10.1038/s41377-022-00740-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 02/01/2022] [Accepted: 02/14/2022] [Indexed: 05/11/2023]
Abstract
The visualization and assessment of retinal microvasculature are important in the study, diagnosis, monitoring, and guidance of treatment of ocular and systemic diseases. With the introduction of optical coherence tomography angiography (OCTA), it has become possible to visualize the retinal microvasculature volumetrically and without a contrast agent. Many lab-based and commercial clinical instruments, imaging protocols and data analysis methods and metrics, have been applied, often inconsistently, resulting in a confusing picture that represents a major barrier to progress in applying OCTA to reduce the burden of disease. Open data and software sharing, and cross-comparison and pooling of data from different studies are rare. These inabilities have impeded building the large databases of annotated OCTA images of healthy and diseased retinas that are necessary to study and define characteristics of specific conditions. This paper addresses the steps needed to standardize OCTA imaging of the human retina to address these limitations. Through review of the OCTA literature, we identify issues and inconsistencies and propose minimum standards for imaging protocols, data analysis methods, metrics, reporting of findings, and clinical practice and, where this is not possible, we identify areas that require further investigation. We hope that this paper will encourage the unification of imaging protocols in OCTA, promote transparency in the process of data collection, analysis, and reporting, and facilitate increasing the impact of OCTA on retinal healthcare delivery and life science investigations.
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Affiliation(s)
- Danuta M Sampson
- Surrey Biophotonics, Centre for Vision, Speech and Signal Processing and School of Biosciences and Medicine, The University of Surrey, Guildford, GU2 7XH, UK.
| | - Adam M Dubis
- NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Trust and UCL Institute of Ophthalmology, London, EC1V 2PD, UK
| | - Fred K Chen
- Centre for Ophthalmology and Visual Science (incorporating Lions Eye Institute), The University of Western Australia, Nedlands, Western Australia, 6009, Australia
- Department of Ophthalmology, Royal Perth Hospital, Perth, Western Australia, 6000, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, Victoria, 3002, Australia
| | - Robert J Zawadzki
- Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA, 95817, USA
| | - David D Sampson
- Surrey Biophotonics, Advanced Technology Institute, School of Physics and School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, GU2 7XH, UK
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8
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Moult EM, Shi Y, Zhang Q, Wang L, Mazumder R, Chen S, Chu Z, Feuer W, Waheed NK, Gregori G, Wang RK, Rosenfeld PJ, Fujimoto JG. Analysis of correlations between local geographic atrophy growth rates and local OCT angiography-measured choriocapillaris flow deficits. BIOMEDICAL OPTICS EXPRESS 2021; 12:4573-4595. [PMID: 34457433 PMCID: PMC8367222 DOI: 10.1364/boe.427819] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/21/2021] [Accepted: 06/26/2021] [Indexed: 06/13/2023]
Abstract
The purpose of this study is to quantitatively assess correlations between local geographic atrophy (GA) growth rates and local optical coherence tomography angiography (OCTA)-measured choriocapillaris (CC) flow deficits. Thirty-eight eyes from 27 patients with GA secondary to age-related macular degeneration (AMD) were imaged with a commercial 1050 nm swept-source OCTA instrument at 3 visits, each separated by ∼6 months. Pearson correlations were computed between local GA growth rates, estimated using a biophysical GA growth model, and local OCTA CC flow deficit percentages measured along the GA margins of the baseline visits. The p-values associated with the null hypothesis of no Pearson correlation were estimated using a Monte Carlo permutation scheme that incorporates the effects of spatial autocorrelation. The null hypothesis (Pearson's ρ = 0) was rejected at a Benjamini-Hochberg false discovery rate of 0.2 in 15 of the 114 visit pairs, 11 of which exhibited positive correlations; even amongst these 11 visit pairs, correlations were modest (r in [0.30, 0.53]). The presented framework appears well suited to evaluating other potential imaging biomarkers of local GA growth rates.
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Affiliation(s)
- Eric M. Moult
- Department of Electrical Engineering and
Computer Science, Research Laboratory of Electronics,
Massachusetts Institute of Technology,
Cambridge, MA 02139-4307, USA
- Health Sciences and Technology,
Harvard & Massachusetts Institute of
Technology, Cambridge, MA 02139-4307, USA
| | - Yingying Shi
- Department of Ophthalmology, Bascom Palmer
Eye Institute, University of Miami Miller School of
Medicine, Miami, FL 33136, USA
| | - Qinqin Zhang
- Department of Bioengineering,
University of Washington, Seattle, WA
98104, USA
| | - Liang Wang
- Department of Ophthalmology, Bascom Palmer
Eye Institute, University of Miami Miller School of
Medicine, Miami, FL 33136, USA
| | - Rahul Mazumder
- Sloan School of Management, Operations
Research Center and Center for Statistics, Massachusetts
Institute of Technology, Cambridge, MA 02139-4307,
USA
| | - Siyu Chen
- Department of Electrical Engineering and
Computer Science, Research Laboratory of Electronics,
Massachusetts Institute of Technology,
Cambridge, MA 02139-4307, USA
| | - Zhongdi Chu
- Department of Bioengineering,
University of Washington, Seattle, WA
98104, USA
| | - William Feuer
- Department of Ophthalmology, Bascom Palmer
Eye Institute, University of Miami Miller School of
Medicine, Miami, FL 33136, USA
| | - Nadia K. Waheed
- New England Eye
Center, Tufts Medical Center, Boston, MA 02111, USA
| | - Giovanni Gregori
- Department of Ophthalmology, Bascom Palmer
Eye Institute, University of Miami Miller School of
Medicine, Miami, FL 33136, USA
| | - Ruikang K. Wang
- Department of Bioengineering,
University of Washington, Seattle, WA
98104, USA
| | - Philip J. Rosenfeld
- Department of Ophthalmology, Bascom Palmer
Eye Institute, University of Miami Miller School of
Medicine, Miami, FL 33136, USA
| | - James G. Fujimoto
- Department of Electrical Engineering and
Computer Science, Research Laboratory of Electronics,
Massachusetts Institute of Technology,
Cambridge, MA 02139-4307, USA
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Hepburn MS, Foo KY, Wijesinghe P, Munro PRT, Chin L, Kennedy BF. Speckle-dependent accuracy in phase-sensitive optical coherence tomography. OPTICS EXPRESS 2021; 29:16950-16968. [PMID: 34154247 DOI: 10.1364/oe.417954] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 03/26/2021] [Indexed: 05/25/2023]
Abstract
Phase-sensitive optical coherence tomography (OCT) is used to measure motion in a range of techniques, such as Doppler OCT and optical coherence elastography (OCE). In phase-sensitive OCT, motion is typically estimated using a model of the OCT signal derived from a single reflector. However, this approach is not representative of turbid samples, such as tissue, which exhibit speckle. In this study, for the first time, we demonstrate, through theory and experiment that speckle significantly lowers the accuracy of phase-sensitive OCT in a manner not accounted for by the OCT signal-to-noise ratio (SNR). We describe how the inaccuracy in speckle reduces phase difference sensitivity and introduce a new metric, speckle brightness, to quantify the amount of constructive interference at a given location in an OCT image. Experimental measurements show an almost three-fold degradation in sensitivity between regions of high and low speckle brightness at a constant OCT SNR. Finally, we apply these new results in compression OCE to demonstrate a ten-fold improvement in strain sensitivity, and a five-fold improvement in contrast-to-noise by incorporating independent speckle realizations. Our results show that speckle introduces a limit to the accuracy of phase-sensitive OCT and that speckle brightness should be considered to avoid erroneous interpretation of experimental data.
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10
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Ghafaryasl B, Vermeer KA, Kalkman J, Callewaert T, de Boer JF, van Vliet LJ. Attenuation coefficient estimation in Fourier-domain OCT of multi-layered phantoms. BIOMEDICAL OPTICS EXPRESS 2021; 12:2744-2758. [PMID: 34123501 PMCID: PMC8176795 DOI: 10.1364/boe.415079] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 01/11/2021] [Accepted: 01/11/2021] [Indexed: 05/11/2023]
Abstract
Optical properties, such as the attenuation coefficients of multi-layer tissue samples, could be used as a biomarker for diagnosis and disease progression in clinical practice. In this paper, we present a method to estimate the attenuation coefficients in a multi-layer sample by fitting a single scattering model for the OCT signal to the recorded OCT signal. In addition, we employ numerical simulations to obtain the theoretically achievable precision and accuracy of the estimated parameters under various experimental conditions. Finally, the method is applied to two sets of measurements obtained from a multi-layer phantom by two experimental OCT systems: one with a large and one with a small Rayleigh length. Numerical and experimental results show an accurate estimation of the attenuation coefficients when using multiple B-scans.
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Affiliation(s)
- Babak Ghafaryasl
- Rotterdam Ophthalmic Institute, Rotterdam Eye Hospital, 3011 BH, Rotterdam, The Netherlands
- Department of Imaging Physics, Delft University of Technology, 2628 CJ, Delft, The Netherlands
| | - Koenraad A. Vermeer
- Rotterdam Ophthalmic Institute, Rotterdam Eye Hospital, 3011 BH, Rotterdam, The Netherlands
| | - Jeroen Kalkman
- Department of Imaging Physics, Delft University of Technology, 2628 CJ, Delft, The Netherlands
| | - Tom Callewaert
- Department of Imaging Physics, Delft University of Technology, 2628 CJ, Delft, The Netherlands
| | - Johannes F. de Boer
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, 1081 HV, Amsterdam, The Netherlands
| | - Lucas J. van Vliet
- Department of Imaging Physics, Delft University of Technology, 2628 CJ, Delft, The Netherlands
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SPATIAL DISTRIBUTION OF CHORIOCAPILLARIS IMPAIRMENT IN EYES WITH CHOROIDAL NEOVASCULARIZATION SECONDARY TO AGE-RELATED MACULAR DEGENERATION: A Quantitative OCT Angiography Study. Retina 2021; 40:428-445. [PMID: 31415449 DOI: 10.1097/iae.0000000000002556] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To develop an optical coherence tomography angiography (OCTA)-based framework for quantitatively analyzing the spatial distribution of choriocapillaris (CC) impairment around choroidal neovascularization (CNV) secondary to age-related macular degeneration. METHODS In a retrospective, cross-sectional study, 400-kHz swept-source OCTA images from 7 eyes of 6 patients with CNV secondary to age-related macular degeneration were quantitatively analyzed using custom software. A lesion-centered zonal OCTA analysis technique-which portioned the field-of-view into zones relative to CNV boundaries-was developed to quantify the spatial dependence of CC flow deficits. RESULTS Quantitative, lesion-centered zonal analysis of CC OCTA images revealed highest flow-deficit percentages near CNV boundaries, decreasing in zones farther from the boundaries. Optical coherence tomography angiography using shorter (1.5 ms) interscan times revealed more severe flow deficits than OCTA using longer (3.0 ms) interscan times; however, spatial trends were similar for both interscan times. A detailed description of the OCTA processing steps and parameters was provided so as to elucidate their influence on quantitative measurements. CONCLUSION Impairment of the CC, assessed by flow-deficit percentages, was most prominent closest to CNV boundaries. The lesion-centered zonal analysis technique enabled quantitative CC measurements relative to focal lesions. Understanding how processing steps, imaging/processing parameters, and artifacts can affect quantitative CC measurements is important for longitudinal, OCTA-based studies of disease progression, and treatment response.
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12
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Smid LM, Vermeer KA, Wong KT, Martinez Ciriano JP, de Jong JH, Davidoiu V, de Boer JF, van Velthoven MEJ. Detailed optical coherence tomography angiographic short-term response of type 3 neovascularization to combined treatment with photodynamic therapy and intravitreal bevacizumab. Acta Ophthalmol 2021; 99:207-214. [PMID: 32602240 PMCID: PMC7983957 DOI: 10.1111/aos.14525] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 05/28/2020] [Indexed: 12/11/2022]
Abstract
PURPOSE To explore the short-term vascular and structural changes of type 3 neovascularization using optical coherence tomography angiography (OCT-A) when treated with a combination of photodynamic therapy (PDT) and intravitreal bevacizumab (IVB), and to evaluate the course of different sequences of the combined therapies. METHODS Thirty eyes of 29 treatment-naïve patients with a type 3 neovascularization were included in this prospective observational cohort study. They were all treated with PDT and IVB 2 weeks apart, starting either with PDT (PDT-first group) or IVB (IVB-first group). Optical coherence tomography angiography (OCT-A) imaging was performed at week 0, 2, 4 and 18, and best corrected visual acuity (BCVA) at week 0 and 18. Vascular, structural and functional features were graded and analysed over time. RESULTS In all patients, at all follow-up visits, vascular and structural features were significantly more often decreased or resolved than unchanged or increased. Best corrected visual acuity (BCVA) significantly improved at 18 weeks. Vascular, structural and functional outcomes were all slightly better in the PDT-first group compared to the IVB-first group, although not statistically significant. CONCLUSION Combined treatment of PDT and IVB is effective in short-term for type 3 neovascularization based on vascular and structural features. Initial treatment with PDT tended to be more effective than with IVB.
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Affiliation(s)
| | | | | | | | | | - Valentina Davidoiu
- Institute for Lasers, Life and Biophotonics AmsterdamDepartment of Physics and AstronomyVU UniversityAmsterdamThe Netherlands
| | - Johannes F. de Boer
- Institute for Lasers, Life and Biophotonics AmsterdamDepartment of Physics and AstronomyVU UniversityAmsterdamThe Netherlands
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13
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Chen TH, Wu YC, Tsai TY, Chueh CB, Huang BH, Huang YP, Tsai MT, Yasuno Y, Lee HC. Effect of A-scan rate and interscan interval on optical coherence angiography. BIOMEDICAL OPTICS EXPRESS 2021; 12:722-736. [PMID: 33680538 PMCID: PMC7901325 DOI: 10.1364/boe.409636] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 12/04/2020] [Accepted: 12/22/2020] [Indexed: 05/25/2023]
Abstract
Optical coherence tomography angiography (OCTA) can provide rapid, volumetric, and noninvasive imaging of tissue microvasculature without the requirement of exogenous contrast agents. To investigate how A-scan rate and interscan time affected the contrast and dynamic range of OCTA, we developed a 1.06-µm swept-source OCT system enabling 100-kHz or 200-kHz OCT using two light sources. After system settings were carefully adjusted, almost the same detection sensitivity was achieved between the 100-kHz and 200-kHz modalities. OCTA of ear skin was performed on five mice. We used the variable interscan time analysis algorithm (VISTA) and the designated scanning protocol with OCTA images reconstructed through the correlation mapping method. With a relatively long interscan time (e.g., 12.5 ms vs. 6.25 ms for 200-kHz OCT), OCTA can identify more intricate microvascular networks. OCTA image sets with the same interscan time (e.g., 12.5 ms) were compared. OCTA images acquired with a 100-kHz A-scan rate showed finer microvasculature than did other imaging modalities. We performed quantitative analysis on the contrast from OCTA images reconstructed with different A-scan rates and interscan time intervals in terms of vessel area, total vessel length, and junction density.
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Affiliation(s)
- Ting-Hao Chen
- Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan
| | - Yi-Chun Wu
- Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan
| | - Ting-Yen Tsai
- Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan
| | - Chuan-Bor Chueh
- Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan
| | - Bo-Huei Huang
- Department of Electrical Engineering, Chang Gung University, Taoyuan 33302, Taiwan
| | - Yin-Peng Huang
- Graduate Institute of Networking and Multimedia, National Taiwan University, Taipei 10617, Taiwan
| | - Meng-Tsan Tsai
- Department of Electrical Engineering, Chang Gung University, Taoyuan 33302, Taiwan
- Department of Neurosurgery, Chang Gung Memorial Hospital, Linkou, Taoyuan 33306, Taiwan
| | - Yoshiaki Yasuno
- Computational Optics Group, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-8573, Japan
| | - Hsiang-Chieh Lee
- Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan
- Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan
- Molecular Imaging Center, National Taiwan University, Taipei 10617, Taiwan
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14
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Shin I, Oh WY. Visualization of two-dimensional transverse blood flow direction using optical coherence tomography angiography. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:JBO-200253R. [PMID: 33331149 PMCID: PMC7739998 DOI: 10.1117/1.jbo.25.12.126003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 11/24/2020] [Indexed: 05/02/2023]
Abstract
SIGNIFICANCE Evaluation of vessel patency and blood flow direction is important in various medical situations, including diagnosis and monitoring of ischemic diseases, and image-guided vascular surgeries. While optical coherence tomography angiography (OCTA) is the most widely used functional extension of optical coherence tomography that visualizes three-dimensional vasculature, inability to provide information of blood flow direction is one of its limitations. AIM We demonstrate two-dimensional (2D) transverse blood flow direction imaging in en face OCTA. APPROACH A series of triangular beam scans for the fast axis was implemented in the horizontal direction for the first volume scan and in the vertical direction for the following volume scan, and the inter A-line OCTA was performed for the blood flow direction imaging while the stepwise pattern was used for each slow axis scan. The decorrelation differences between the forward and the backward inter A-line OCTA were calculated for the horizontal and the vertical fast axis scans, and the ratio of the horizontal and the vertical decorrelation differences was utilized to show the 2D transverse flow direction information. RESULTS OCTA flow direction imaging was verified using flow phantoms with various flow orientations and speeds, and we identified the flow speed range relative to the scan speed for reliable flow direction measurement. We demonstrated the visualization of 2D transverse blood flow orientations in mouse brain vascular networks in vivo. CONCLUSIONS The proposed OCTA imaging technique that provides information of 2D transverse flow direction can be utilized in various clinical applications and preclinical studies.
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Affiliation(s)
- Inho Shin
- Korea Advanced Institute of Science and Technology, Department of Mechanical Engineering, Daejeon, Republic of Korea
- Korea Advanced Institute of Science and Technology, KI for Health Science and Technology, Daejeon, Republic of Korea
| | - Wang-Yuhl Oh
- Korea Advanced Institute of Science and Technology, Department of Mechanical Engineering, Daejeon, Republic of Korea
- Korea Advanced Institute of Science and Technology, KI for Health Science and Technology, Daejeon, Republic of Korea
- Address all correspondence to Wang-Yuhl Oh,
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15
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Yun YI, Kim YW, Lim HB, Lee DH, Kim JH, Oh BL, Jeoung JW, Park KH. Peripapillary vessel parameters and mean ocular perfusion pressure in young healthy eyes: OCT angiography study. Br J Ophthalmol 2020; 105:862-868. [PMID: 32703786 DOI: 10.1136/bjophthalmol-2020-316222] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 05/16/2020] [Accepted: 06/18/2020] [Indexed: 12/24/2022]
Abstract
BACKGROUND To investigate the relationship between estimated mean ocular perfusion pressure (MOPP) and peripapillary perfusion density (PD) or vessel density (VD) as measured by spectral-domain optical coherence tomography angiography (OCTA) in young healthy eyes. METHODS 132 healthy participants (264 eyes) under 45 years of age underwent optic disc OCTA scan sized 3×3 mm to acquire PD and VD in the superficial vascular complex (SVC). Optic nerve head (ONH) parameters including retinal nerve fibre layer (RNFL) thickness, rim area and disc area were measured. MOPP was estimated from systemic blood pressure and intraocular pressure (IOP). A linear mixed model was used to find the systemic and ocular factors associated with PD and VD. RESULTS The average age of the subjects was 25.8±6.5 years. PD and VD showed a significant correlation with RNFL thickness (r=0.224, p<0.001 and r=0.214, p<0.001, respectively), but with MOPP, the correlation was only marginally significant (r=0.105, p=0.09 and r=0.112, p=0.07, respectively). After controlling for confounding factors, including age, sex, IOP, central corneal thickness, axial length and OCTA signal strength, PD and VD were significantly associated with ONH parameters (all p<0.05) but not with estimated MOPP (all p>0.05). CONCLUSION PD and VD in the SVC were significantly associated with ONH parameters while showing no association with estimated MOPP. OCTA-derived VD may not represent perfusion pressure, but is rather more dependent on peripapillary structure.
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Affiliation(s)
- Young In Yun
- Department of Ophthalmology, Seoul National University Hospital, Seoul, Republic of Korea
| | - Yong Woo Kim
- Department of Ophthalmology, Seoul National University Hospital, Seoul, Republic of Korea .,Department of Ophthalmology, Armed Forces Capital Hospital, Seongnam, Republic of Korea
| | - Hyung Bin Lim
- Department of Ophthalmology, Armed Forces Capital Hospital, Seongnam, Republic of Korea.,Department of Ophthalmology, Chungnam National University Hospital, Daejeon, Republic of Korea
| | - Dong Hyun Lee
- Department of Ophthalmology, Armed Forces Capital Hospital, Seongnam, Republic of Korea.,Department of Ophthalmology, Gangnam Severance Hospital, Seoul, Republic of Korea
| | - Ji Hong Kim
- Department of Ophthalmology, Armed Forces Capital Hospital, Seongnam, Republic of Korea
| | - Baek-Lok Oh
- Department of Ophthalmology, Seoul National University Hospital, Seoul, Republic of Korea.,Department of Ophthalmology, Armed Forces Capital Hospital, Seongnam, Republic of Korea
| | - Jin Wook Jeoung
- Department of Ophthalmology, Seoul National University Hospital, Seoul, Republic of Korea
| | - Ki Ho Park
- Department of Ophthalmology, Seoul National University Hospital, Seoul, Republic of Korea
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16
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Fan J, He Y, Wang P, Liu G, Shi G. Interplane bulk motion analysis and removal based on normalized cross-correlation in optical coherence tomography angiography. JOURNAL OF BIOPHOTONICS 2020; 13:e202000046. [PMID: 32359023 DOI: 10.1002/jbio.202000046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/09/2020] [Accepted: 04/27/2020] [Indexed: 06/11/2023]
Abstract
Bulk motion seriously degrades the image quality of optical coherence tomography angiography (OCTA). Conventional correction methods focus on in-plane displacement, while the bulk motion component perpendicular to B-scans also introduces noise. This work first presents an evaluation of this component using a specific scan protocol and an approximate expression derived from peak-normalized cross-correlation values, and then quantitatively assesses how interplane bulk motion noise reduce the sensitivity of cross-sectional angiograms. Finally, we developed a repetitive bulk motion correction method based on the estimated displacements and redundant volume scans. The correction does not require registration and angiogram reconstruction of low flow sensitivity frames, and the results of in vivo mice skin OCTA imaging experiments show that the proposed method can effectively reduce bulk motion noise caused by cardiac and respiratory motion and occasional shaking, and improve OCTA image quality, which has practical significance for clinical OCTA diagnosis and analysis.
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Affiliation(s)
- Jinyu Fan
- Department of biomedical Engineering, University of Science and Technology of China, Hefei, China
- Jiangsu Key Laboratory of Medical Optics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China
| | - Yi He
- Jiangsu Key Laboratory of Medical Optics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China
| | - Pinghe Wang
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Guangxing Liu
- Jiangsu Key Laboratory of Medical Optics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China
| | - Guohua Shi
- Department of biomedical Engineering, University of Science and Technology of China, Hefei, China
- Jiangsu Key Laboratory of Medical Optics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
- Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
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17
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Kim TS, Joo J, Shin I, Shin P, Kang WJ, Vakoc BJ, Oh WY. 9.4 MHz A-line rate optical coherence tomography at 1300 nm using a wavelength-swept laser based on stretched-pulse active mode-locking. Sci Rep 2020; 10:9328. [PMID: 32518256 PMCID: PMC7283258 DOI: 10.1038/s41598-020-66322-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 05/08/2020] [Indexed: 01/07/2023] Open
Abstract
In optical coherence tomography (OCT), high-speed systems based at 1300 nm are among the most broadly used. Here, we present 9.4 MHz A-line rate OCT system at 1300 nm. A wavelength-swept laser based on stretched-pulse active mode locking (SPML) provides a continuous and linear-in-wavenumber sweep from 1240 nm to 1340 nm, and the OCT system using this light source provides a sensitivity of 98 dB and a single-sided 6-dB roll-off depth of 2.5 mm. We present new capabilities of the 9.4 MHz SPML-OCT system in three microscopy applications. First, we demonstrate high quality OCTA imaging at a rate of 1.3 volumes/s. Second, by utilizing its inherent phase stable characteristics, we present wide dynamic range en face Doppler OCT imaging with multiple time intervals ranging from 0.25 ms to 2.0 ms at a rate of 0.53 volumes/s. Third, we demonstrate video-rate 4D microscopic imaging of a beating Xenopus embryo heart at a rate of 30 volumes/s. This high-speed and high-performance OCT system centered at 1300 nm suggests that it can be one of the most promising high-speed OCT platforms enabling a wide range of new scientific research, industrial, and clinical applications at speeds of 10 MHz.
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Affiliation(s)
- Tae Shik Kim
- Department of Mechanical Engineering, KAIST, Daejeon, Republic of Korea.,KI for Health Science and Technology, KAIST, Daejeon, Republic of Korea
| | - JongYoon Joo
- Department of Mechanical Engineering, KAIST, Daejeon, Republic of Korea.,KI for Health Science and Technology, KAIST, Daejeon, Republic of Korea
| | - Inho Shin
- Department of Mechanical Engineering, KAIST, Daejeon, Republic of Korea.,KI for Health Science and Technology, KAIST, Daejeon, Republic of Korea
| | - Paul Shin
- Department of Mechanical Engineering, KAIST, Daejeon, Republic of Korea.,KI for Health Science and Technology, KAIST, Daejeon, Republic of Korea
| | - Woo Jae Kang
- Department of Mechanical Engineering, KAIST, Daejeon, Republic of Korea.,KI for Health Science and Technology, KAIST, Daejeon, Republic of Korea
| | - Benjamin J Vakoc
- Wellman Center for Photomedicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
| | - Wang-Yuhl Oh
- Department of Mechanical Engineering, KAIST, Daejeon, Republic of Korea. .,KI for Health Science and Technology, KAIST, Daejeon, Republic of Korea.
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18
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Tanguy QAA, Gaiffe O, Passilly N, Cote JM, Cabodevila G, Bargiel S, Lutz P, Xie H, Gorecki C. Real-time Lissajous imaging with a low-voltage 2-axis MEMS scanner based on electrothermal actuation. OPTICS EXPRESS 2020; 28:8512-8527. [PMID: 32225475 DOI: 10.1364/oe.380690] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 01/29/2020] [Indexed: 05/28/2023]
Abstract
Laser scanning based on Micro-Electro-Mechanical Systems (MEMS) scanners has become very attractive for biomedical endoscopic imaging, such as confocal microscopy or Optical Coherence Tomography (OCT). These scanners are required to be fast to achieve real-time image reconstruction while working at low actuation voltage to comply with medical standards. In this context, we report a 2-axis Micro-Electro-Mechanical Systems (MEMS) electrothermal micro-scannercapable of imaging large fields of view at high frame rates, e.g. from 10 to 80 frames per second. For this purpose, Lissajous scan parameters are chosen to provide the optimal image quality within the scanner capabilities and the sampling rate limit, resulting from the limited A-scan rate of typical swept-sources used for OCT. Images of 233 px × 203 px and 53 px × 53 px at 10 fps and 61 fps, respectively, are experimentally obtained and demonstrate the potential of this micro-scannerfor high definition and high frame rate endoscopic Lissajous imaging.
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19
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Gräfe MGO, Nadiarnykh O, De Boer JF. Optical coherence tomography velocimetry based on decorrelation estimation of phasor pair ratios (DEPPAIR). BIOMEDICAL OPTICS EXPRESS 2019; 10:5470-5485. [PMID: 31799025 PMCID: PMC6865093 DOI: 10.1364/boe.10.005470] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 09/17/2019] [Accepted: 09/20/2019] [Indexed: 05/13/2023]
Abstract
Quantitative velocity estimations in optical coherence tomography requires the estimation of the axial and lateral flow components. Optical coherence tomography measures the depth resolved complex field reflected from a sample. While the axial velocity component can be determined from the Doppler shift or phase shift between a pair of consecutive measurements at the same location, the estimation of the lateral component for in vivo applications is still challenging. One approach to determine lateral velocity is multiple simultaneous measurements at different angles. In another approach the lateral component can be retrieved through repeated measurements at (nearly) the same location by an analysis of the decorrelation over time. In this paper we follow the latter approach. We describe a model for the complex field changes between consecutive measurements and use it to predict the uncertainties for amplitude-based, phase-based and complex algorithms. The uncertainty of the flow estimations follows from a statistical analysis and is determined by the number of available measurements and the applied analysis method. The model is verified in phantom measurements and the dynamic range of velocity estimations is investigated. We demonstrate that phase-based and complex (phasor) based lateral flow estimation methods are superior to amplitude-based algorithms.
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20
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Zhang P, Miller EB, Manna SK, Meleppat RK, Pugh EN, Zawadzki RJ. Temporal speckle-averaging of optical coherence tomography volumes for in-vivo cellular resolution neuronal and vascular retinal imaging. NEUROPHOTONICS 2019; 6:041105. [PMID: 31528657 PMCID: PMC6732665 DOI: 10.1117/1.nph.6.4.041105] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 07/31/2019] [Indexed: 05/08/2023]
Abstract
It has been recently demonstrated that structures corresponding to the cell bodies of highly transparent cells in the retinal ganglion cell layer could be visualized noninvasively in the living human eye by optical coherence tomography (OCT) via temporal averaging. Inspired by this development, we explored the application of volumetric temporal averaging in mice, which are important models for studying human retinal diseases and therapeutic interventions. A general framework of temporal speckle-averaging (TSA) of OCT and optical coherence tomography angiography (OCTA) is presented and applied to mouse retinal volumetric data. Based on the image analysis, the eyes of mice under anesthesia exhibit only minor motions, corresponding to lateral displacements of a few micrometers and rotations of a fraction of 1 deg. Moreover, due to reduced eye movements under anesthesia, there is a negligible amount of motion artifacts within the volumes that need to be corrected to achieve volume coregistration. In addition, the relatively good optical quality of the mouse ocular media allows for cellular-resolution imaging without adaptive optics (AO), greatly simplifying the experimental system, making the proposed framework feasible for large studies. The TSA OCT and TSA OCTA results provide rich information about new structures previously not visualized in living mice with non-AO-OCT. The mechanism of TSA relies on improving signal-to-noise ratio as well as efficient suppression of speckle contrast due to temporal decorrelation of the speckle patterns, enabling full utilization of the high volumetric resolution offered by OCT and OCTA.
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Affiliation(s)
- Pengfei Zhang
- University of California Davis, Department of Cell Biology and Human Anatomy, UC Davis Eye-Pod Small Animal Ocular Imaging Laboratory, Davis, California, United States
| | - Eric B. Miller
- University of California Davis, Center for Neuroscience, Davis, California, United States
| | - Suman K. Manna
- University of California Davis, Department of Cell Biology and Human Anatomy, UC Davis Eye-Pod Small Animal Ocular Imaging Laboratory, Davis, California, United States
| | - Ratheesh K. Meleppat
- University of California Davis, Department of Cell Biology and Human Anatomy, UC Davis Eye-Pod Small Animal Ocular Imaging Laboratory, Davis, California, United States
| | - Edward N. Pugh
- University of California Davis, Department of Cell Biology and Human Anatomy, UC Davis Eye-Pod Small Animal Ocular Imaging Laboratory, Davis, California, United States
- University of California Davis, Department of Ophthalmology and Vision Science, Vision Science and Advanced Retinal Imaging Laboratory, Sacramento, California, United States
| | - Robert J. Zawadzki
- University of California Davis, Department of Cell Biology and Human Anatomy, UC Davis Eye-Pod Small Animal Ocular Imaging Laboratory, Davis, California, United States
- University of California Davis, Department of Ophthalmology and Vision Science, Vision Science and Advanced Retinal Imaging Laboratory, Sacramento, California, United States
- University of California Davis, UC Davis Eye Center, Department of Ophthalmology and Vision Science, Sacramento, California, United States
- Address all correspondence to Robert J. Zawadzki, E-mail:
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21
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Wei X, Hormel TT, Pi S, Guo Y, Jian Y, Jia Y. High dynamic range optical coherence tomography angiography (HDR-OCTA). BIOMEDICAL OPTICS EXPRESS 2019; 10:3560-3571. [PMID: 31360605 PMCID: PMC6640830 DOI: 10.1364/boe.10.003560] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 05/29/2019] [Accepted: 06/18/2019] [Indexed: 05/25/2023]
Abstract
The dynamic range of current optical coherence tomography (OCT) angiography (OCTA) images is limited by the fixed scanning intervals. High speed OCT devices introduce the possibility of extending the flow signal dynamic range. In this study, we created a novel scanning pattern for achieving high dynamic range (HDR)-OCTA with a superior scanning efficiency. We implemented a bidirectional, interleaved scanning pattern that is sensitive to different flow speeds by adjustable adjacent inter-scan time intervals. We found that an improved flow dynamic range can be achieved by generating 3 different B-scan time intervals using 3 repetitions.
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Affiliation(s)
- Xiang Wei
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, 97239, USA
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Tristan T. Hormel
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Shaohua Pi
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Yukun Guo
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Yifan Jian
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, 97239, USA
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Yali Jia
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, 97239, USA
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR, 97239, USA
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22
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Feroldi F, Willemse J, Davidoiu V, Gräfe MGO, van Iperen DJ, Goorsenberg AWM, Annema JT, Daniels JMA, Bonta PI, de Boer JF. In vivo multifunctional optical coherence tomography at the periphery of the lungs. BIOMEDICAL OPTICS EXPRESS 2019; 10:3070-3091. [PMID: 31259075 PMCID: PMC6583343 DOI: 10.1364/boe.10.003070] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 05/13/2019] [Accepted: 05/14/2019] [Indexed: 05/04/2023]
Abstract
Remodeling of tissue, such as airway smooth muscle (ASM) and extracellular matrix, is considered a key feature of airways disease. No clinically accepted diagnostic method is currently available to assess airway remodeling or the effect of treatment modalities such as bronchial thermoplasty in asthma, other than invasive airway biopsies. Optical coherence tomography (OCT) generates cross-sectional, near-histological images of airway segments and enables identification and quantification of airway wall layers based on light scattering properties only. In this study, we used a custom motorized OCT probe that combines standard and polarization sensitive OCT (PS-OCT) to visualize birefringent tissue in vivo in the airway wall of a patient with severe asthma in a minimally invasive manner. We used optic axis uniformity (OAxU) to highlight the presence of uniformly arranged fiber-like tissue, helping visualizing the abundance of ASM and connective tissue structures. Attenuation coefficient images of the airways are presented for the first time, showing superior architectural contrast compared to standard OCT images. A novel segmentation algorithm was developed to detect the surface of the endoscope sheath and the surface of the tissue. PS-OCT is an innovative imaging technique that holds promise to assess airway remodeling including ASM and connective tissue in a minimally invasive, real-time manner.
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Affiliation(s)
- Fabio Feroldi
- LaserLaB Amsterdam and Department of Physics and Astronomy, VU University Amsterdam, de Boelelaan 1081, 1081HV, Amsterdam, the Netherlands
| | - Joy Willemse
- LaserLaB Amsterdam and Department of Physics and Astronomy, VU University Amsterdam, de Boelelaan 1081, 1081HV, Amsterdam, the Netherlands
- These authors contributed equally
| | - Valentina Davidoiu
- LaserLaB Amsterdam and Department of Physics and Astronomy, VU University Amsterdam, de Boelelaan 1081, 1081HV, Amsterdam, the Netherlands
- These authors contributed equally
| | - Maximilian G. O. Gräfe
- LaserLaB Amsterdam and Department of Physics and Astronomy, VU University Amsterdam, de Boelelaan 1081, 1081HV, Amsterdam, the Netherlands
| | - Dirck J. van Iperen
- LaserLaB Amsterdam and Department of Physics and Astronomy, VU University Amsterdam, de Boelelaan 1081, 1081HV, Amsterdam, the Netherlands
| | - Annika W. M. Goorsenberg
- Amsterdam University Medical Center, Department of Pulmonology, University of Amsterdam, Amsterdam, the Netherlands
| | - Jouke T. Annema
- Amsterdam University Medical Center, Department of Pulmonology, University of Amsterdam, Amsterdam, the Netherlands
| | - Johannes M. A. Daniels
- Amsterdam University Medical Center, Department of Pulmonology, VUmc Location, Amsterdam, the Netherlands
| | - Peter I. Bonta
- Amsterdam University Medical Center, Department of Pulmonology, University of Amsterdam, Amsterdam, the Netherlands
| | - Johannes F. de Boer
- LaserLaB Amsterdam and Department of Physics and Astronomy, VU University Amsterdam, de Boelelaan 1081, 1081HV, Amsterdam, the Netherlands
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23
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Quantitative Analysis of Retinal and Choroidal Vascular Parameters in Patients With Low Tension Glaucoma. J Glaucoma 2019; 28:557-562. [DOI: 10.1097/ijg.0000000000001242] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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24
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Smid LM, van Overdam KA, Davidoiu V, de Jong JH, de Boer JF, Vermeer KA, van Velthoven ME. Classification and treatment follow-up of a juxtapapillary retinal hemangioblastoma with optical coherence tomography angiography. Am J Ophthalmol Case Rep 2019; 15:100472. [PMID: 31198883 PMCID: PMC6556566 DOI: 10.1016/j.ajoc.2019.100472] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 01/23/2019] [Accepted: 05/15/2019] [Indexed: 11/30/2022] Open
Abstract
Purpose Only an endophytic growth pattern in juxtapapillary retinal hemangioblastoma (JRH) is an indication for surgical treatment, but classification of growth types is difficult using conventional imaging techniques. This case report describes the use of optical coherence tomography angiography (OCT-A) features for classification and treatment follow-up in a case with JRH. Observations The JRH of this patient was easily detected with two different OCT-A methods in both en-face and cross-sectional B-scan images, and was classified as a sessile growth type. This growth type excluded the treatment option of vitreoretinal surgery with excision of the lesion or ligation of the feeder vessels. The patient was treated multiple times with intravitreal bevacizumab. Treatment follow-up with OCT-A initially revealed a stable extent of the JRH, with some slight flow deviations in en-face visualization, followed by a period of progressive growth of the lesion. Conclusions OCT-A revealed the depth localization of the JRH and seems to be a valuable tool for JRH classification. Detailed classification may be useful when surgery is considered as a treatment strategy. Furthermore, treatment follow-up is possible with OCT-A, although imaging artifacts should be taken into account.
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Affiliation(s)
- Lisette M. Smid
- Rotterdam Ophthalmic Institute, Schiedamse Vest 160d, 3011 BH, Rotterdam, the Netherlands
- Corresponding author.
| | - Koen A. van Overdam
- Rotterdam Eye Hospital, Schiedamse Vest 180, 3011 BH, Rotterdam, the Netherlands
| | - Valentina Davidoiu
- Rotterdam Ophthalmic Institute, Schiedamse Vest 160d, 3011 BH, Rotterdam, the Netherlands
- Institute for Lasers, Life and Biophotonics Amsterdam, Department of Physics and Astronomy, VU University, de Boelelaan 1081, 1081 HV, Amsterdam, the Netherlands
| | - Jan H. de Jong
- Rotterdam Ophthalmic Institute, Schiedamse Vest 160d, 3011 BH, Rotterdam, the Netherlands
| | - Johannes F. de Boer
- Institute for Lasers, Life and Biophotonics Amsterdam, Department of Physics and Astronomy, VU University, de Boelelaan 1081, 1081 HV, Amsterdam, the Netherlands
| | - Koenraad A. Vermeer
- Rotterdam Ophthalmic Institute, Schiedamse Vest 160d, 3011 BH, Rotterdam, the Netherlands
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25
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Nadiarnykh O, Davidoiu V, Gräfe MGO, Bosscha M, Moll AC, de Boer JF. Phase-based OCT angiography in diagnostic imaging of pediatric retinoblastoma patients: abnormal blood vessels in post-treatment regression patterns. BIOMEDICAL OPTICS EXPRESS 2019; 10:2213-2226. [PMID: 31143490 PMCID: PMC6524593 DOI: 10.1364/boe.10.002213] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 03/18/2019] [Accepted: 03/19/2019] [Indexed: 05/26/2023]
Abstract
Phase-based OCT angiography of retinoblastoma regression patterns with a novel handheld 1050 nm clinical imaging system is demonstrated for the first time in children between 0 and 4 years old under general anesthesia. Angiography is mapped at OCT resolution by flow detection at every pixel with en-face projection from the volume between nerve fiber layer and retinal pigment epithelium. We show a striking difference between blood vasculature of healthy retina, and retinoblastoma regression patterns after chemotherapy, as well as varying complexity of abnormal vasculature in regression patterns types 2, 3, and 4. We demonstrate abnormal, tortuous and prominent vasculature in type 3 regression patterns having the highest risk of tumor recurrences and a lower probability to reduction into flat scars. The ability to visualize 3-D angiography might offer new insights in understanding of retinoblastoma development and its response to therapy.
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Affiliation(s)
- Oleg Nadiarnykh
- Department of Physics and Astronomy, VU University, De Boelelaan 1081, Amsterdam, 1081 HV, The Netherlands
| | - Valentina Davidoiu
- Department of Physics and Astronomy, VU University, De Boelelaan 1081, Amsterdam, 1081 HV, The Netherlands
| | - Maximilian G. O. Gräfe
- Department of Physics and Astronomy, VU University, De Boelelaan 1081, Amsterdam, 1081 HV, The Netherlands
| | - Machteld Bosscha
- Amsterdam UMC, VU University, Department of Ophthalmology, De Boelelaan 1117, Amsterdam, 1081 HV, The Netherlands
| | - Annette C. Moll
- Amsterdam UMC, VU University, Department of Ophthalmology, De Boelelaan 1117, Amsterdam, 1081 HV, The Netherlands
| | - Johannes F. de Boer
- Department of Physics and Astronomy, VU University, De Boelelaan 1081, Amsterdam, 1081 HV, The Netherlands
- Amsterdam UMC, VU University, Department of Ophthalmology, De Boelelaan 1117, Amsterdam, 1081 HV, The Netherlands
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26
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Gräfe MGO, Gondre M, de Boer JF. Precision analysis and optimization in phase decorrelation OCT velocimetry. BIOMEDICAL OPTICS EXPRESS 2019; 10:1297-1314. [PMID: 30891347 PMCID: PMC6420279 DOI: 10.1364/boe.10.001297] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 01/11/2019] [Accepted: 02/12/2019] [Indexed: 05/13/2023]
Abstract
Quantitative flow velocimetry in Optical Coherence Tomography is used to determine both the axial and lateral flow component at the level of individual voxels. The lateral flow is determined by analyzing the statistical properties of reflected electro-magnetic fields for repeated measurements at (nearly) the same location. The precision or statistical fluctuation of the quantitative velocity estimation depends on the number of repeated measurements and the method to determine quantitative flow velocity. In this paper, both a method to determine quantitative flow velocity and a model for the prediction of the statistical fluctuations of velocity estimations are developed to analyze and optimize the estimation precision for phase-based velocimetry methods. The method and model are validated by phantom measurements in a bulk scattering medium as well as in intralipid solution in a capillary. Based on the model, the number of repeated measurements to achieve a certain velocimetry precision is predicted.
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Affiliation(s)
- Maximilian G. O. Gräfe
- LaserLaB, Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Maude Gondre
- LaserLaB, Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
- Université de Genève, GAP-Biophotonics, Chemin de Pinchat 22, CH-1211 Geneva 4, Switzerland
| | - Johannes F. de Boer
- LaserLaB, Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
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27
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Chlebiej M, Gorczynska I, Rutkowski A, Kluczewski J, Grzona T, Pijewska E, Sikorski BL, Szkulmowska A, Szkulmowski M. Quality improvement of OCT angiograms with elliptical directional filtering. BIOMEDICAL OPTICS EXPRESS 2019; 10:1013-1031. [PMID: 30800529 PMCID: PMC6377873 DOI: 10.1364/boe.10.001013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 01/09/2019] [Accepted: 01/09/2019] [Indexed: 05/06/2023]
Abstract
We present a method of OCT angiography (OCTA) data filtering for noise suppression and improved visualization of the retinal vascular networks in en face projection images. In our approach, we use a set of filters applied in three orthogonal axes in the three-dimensional (3-D) data sets. Minimization of artifacts generated in B-scan-wise data processing is accomplished by filtering the cross-sections along the slow scanning axis. A-scans are de-noised by axial filtering. The core of the method is the application of directional filtering to the C-scans, i.e. one-pixel thick sections of the 3-D data set, perpendicular to the direction of the scanning OCT beam. The method uses a concept of structuring, directional kernels of shapes matching the geometry of the image features. We use rotating ellipses to find the most likely local orientation of the vessels and use the best matching ellipses for median filtering of the C-scans. We demonstrate our approach in the imaging of a normal human eye with laboratory-grade spectral-domain OCT setup. The "field performance" is demonstrated in imaging of diabetic retinopathy cases with a commercial OCT device. The absolute complex differences method is used for the generation of OCTA images from the data collected in the most noise-wise unfavorable OCTA scanning regime-two frame scanning.
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Affiliation(s)
- Michał Chlebiej
- Faculty of Mathematics and Computer Science, Nicolaus Copernicus University in Torun, Chopina 12/18, 87-100 Torun, Poland
- AM2M Ltd. L.P., Mickiewicza 7/17, 87-100 Torun, Poland
| | | | - Andrzej Rutkowski
- Faculty of Mathematics and Computer Science, Nicolaus Copernicus University in Torun, Chopina 12/18, 87-100 Torun, Poland
- AM2M Ltd. L.P., Mickiewicza 7/17, 87-100 Torun, Poland
| | - Jakub Kluczewski
- Faculty of Mathematics and Computer Science, Nicolaus Copernicus University in Torun, Chopina 12/18, 87-100 Torun, Poland
- AM2M Ltd. L.P., Mickiewicza 7/17, 87-100 Torun, Poland
| | - Tomasz Grzona
- Faculty of Mathematics and Computer Science, Nicolaus Copernicus University in Torun, Chopina 12/18, 87-100 Torun, Poland
- AM2M Ltd. L.P., Mickiewicza 7/17, 87-100 Torun, Poland
| | - Ewelina Pijewska
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100 Torun, Poland
| | - Bartosz L. Sikorski
- Department of Ophthalmology, Nicolaus Copernicus University in Torun, 9 M. Sklodowskiej-Curie St., Bydgoszcz, Poland
- Oculomedica Eye Centre, 9 Broniewskiego St. Bydgoszcz, Poland
| | | | - Maciej Szkulmowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100 Torun, Poland
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Migacz JV, Gorczynska I, Azimipour M, Jonnal R, Zawadzki RJ, Werner JS. Megahertz-rate optical coherence tomography angiography improves the contrast of the choriocapillaris and choroid in human retinal imaging. BIOMEDICAL OPTICS EXPRESS 2019; 10:50-65. [PMID: 30775082 PMCID: PMC6363198 DOI: 10.1364/boe.10.000050] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 11/25/2018] [Accepted: 11/27/2018] [Indexed: 05/03/2023]
Abstract
Angiographic imaging of the human eye with optical coherence tomography (OCT) is becoming an increasingly important tool in the scientific investigation and clinical management of several blinding diseases, including age-related macular degeneration and diabetic retinopathy. We have observed that OCT angiography (OCTA) of the human choriocapillaris and choroid with a 1.64 MHz A-scan rate swept-source laser yields higher contrast images as compared to a slower rate system operating at 100 kHz. This result is unexpected because signal sensitivity is reduced when acquisition rates are increased, and the incident illumination power is kept constant. The contrast of angiography images generated by acquiring multiple sequential frames and calculating the variation caused by blood flow, however, appears to be improved significantly when lower-contrast images are taken more rapidly. To demonstrate that the acquisition rate plays a role in the quality improvement, we have imaged five healthy subjects with a narrow field of view (1.2 mm) OCTA imaging system using two separate swept-source lasers of different A-line rates and compared the results quantitatively using the radially-averaged power spectrum. The average improvement in the contrast is 23.0% (+/-7.6%). Although the underlying cause of this enhancement is not explicitly determined here, we speculate that the higher-speed system suppresses the noise contribution from eye motion in subjects and operates with an inter-scan time that better discriminates the flow velocities present in the choroid and choriocapillaris. Our result informs OCT system developers on the merits of ultrahigh-speed acquisition in functional imaging applications.
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Affiliation(s)
- Justin V. Migacz
- Vison Science and Advanced Retinal Imaging Laboratory, Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA 95817, USA
| | - Iwona Gorczynska
- Vison Science and Advanced Retinal Imaging Laboratory, Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA 95817, USA
- Institute of Physics, Faculty of Physics, Astronomy, and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100 Torun, Poland
| | - Mehdi Azimipour
- Vison Science and Advanced Retinal Imaging Laboratory, Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA 95817, USA
| | - Ravi Jonnal
- Vison Science and Advanced Retinal Imaging Laboratory, Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA 95817, USA
| | - Robert J. Zawadzki
- Vison Science and Advanced Retinal Imaging Laboratory, Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA 95817, USA
| | - John S. Werner
- Vison Science and Advanced Retinal Imaging Laboratory, Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA 95817, USA
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29
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de Jong JH, Braaf B, Amarakoon S, Gräfe M, Yzer S, Vermeer KA, Missotten T, de Boer JF, van Velthoven MEJ. Treatment Effects in Retinal Angiomatous Proliferation Imaged with OCT Angiography. Ophthalmologica 2018; 241:143-153. [PMID: 30227415 DOI: 10.1159/000491798] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 07/04/2018] [Indexed: 11/19/2022]
Abstract
PURPOSE This prospective case series is aimed at exploring optical coherence tomographic angiography (OCT-A) as a treatment monitoring tool in patients treated for retinal angiomatous proliferation (RAP). METHODS Twelve treatment-naïve RAP patients were included, with a median age of 79 years (range 65-90). Patients were imaged with an experimental 1,040-nm swept-source phase-resolved OCT-A instrument before and after treatment. Treatment consisted of either intravitreal bevacizumab or triamcinolone injections with or without photodynamic therapy (PDT). Abnormal blood flow after treatment was graded as increased, unchanged, decreased, or resolved. RESULTS OCT-A images before and after treatment could be obtained in 9 patients. The median follow-up period was 10 weeks (range 5-19). After various treatments, the RAP lesion resolved in 7 patients, in 1 patient the OCT-A depicted decreased flow in the lesion, and 1 patient showed unchanged abnormal blood flow. Monotherapy with intravitreal bevacizumab injections resolved RAP in 1 out of 2 patients. Combined therapy of bevacizumab with PDT resolved RAP in 6 out of 7 patients. CONCLUSIONS OCT-A visualized resolution of abnormal blood flow in 7 out of 9 RAP patients after various short-term treatment sequences. OCT-A may become an important noninvasive monitoring tool for optimizing treatment strategies in RAP patients.
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Affiliation(s)
- Jan H de Jong
- Rotterdam Ophthalmic Institute, Rotterdam, The Netherlands.,Rotterdam Eye Hospital, Rotterdam, The Netherlands
| | - Boy Braaf
- Institute for Lasers, Life and Biophotonics Amsterdam, Department of Physics and Astronomy, VU University, Amsterdam, The Netherlands
| | - Sankha Amarakoon
- Rotterdam Ophthalmic Institute, Rotterdam, The Netherlands.,Rotterdam Eye Hospital, Rotterdam, The Netherlands
| | - Maximilian Gräfe
- Institute for Lasers, Life and Biophotonics Amsterdam, Department of Physics and Astronomy, VU University, Amsterdam, The Netherlands
| | - Suzanne Yzer
- Rotterdam Ophthalmic Institute, Rotterdam, The Netherlands.,Rotterdam Eye Hospital, Rotterdam, The Netherlands
| | | | - Tom Missotten
- Rotterdam Ophthalmic Institute, Rotterdam, The Netherlands.,Rotterdam Eye Hospital, Rotterdam, The Netherlands
| | - Johannes F de Boer
- Rotterdam Ophthalmic Institute, Rotterdam, The Netherlands.,Institute for Lasers, Life and Biophotonics Amsterdam, Department of Physics and Astronomy, VU University, Amsterdam, The Netherlands
| | - Mirjam E J van Velthoven
- Rotterdam Ophthalmic Institute, Rotterdam, The Netherlands, .,Rotterdam Eye Hospital, Rotterdam, The Netherlands,
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30
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Potential applications of optical coherence tomography angiography in glaucoma. Curr Opin Ophthalmol 2018; 29:226-233. [DOI: 10.1097/icu.0000000000000475] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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31
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Spaide RF, Fujimoto JG, Waheed NK, Sadda SR, Staurenghi G. Optical coherence tomography angiography. Prog Retin Eye Res 2018; 64:1-55. [PMID: 29229445 PMCID: PMC6404988 DOI: 10.1016/j.preteyeres.2017.11.003] [Citation(s) in RCA: 985] [Impact Index Per Article: 164.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 11/20/2017] [Accepted: 11/22/2017] [Indexed: 02/07/2023]
Abstract
Optical coherence tomography (OCT) was one of the biggest advances in ophthalmic imaging. Building on that platform, OCT angiography (OCTA) provides depth resolved images of blood flow in the retina and choroid with levels of detail far exceeding that obtained with older forms of imaging. This new modality is challenging because of the need for new equipment and processing techniques, current limitations of imaging capability, and rapid advancements in both imaging and in our understanding of the imaging and applicable pathophysiology of the retina and choroid. These factors lead to a steep learning curve, even for those with a working understanding dye-based ocular angiography. All for a method of imaging that is a little more than 10 years old. This review begins with a historical account of the development of OCTA, and the methods used in OCTA, including signal processing, image generation, and display techniques. This forms the basis to understand what OCTA images show as well as how image artifacts arise. The anatomy and imaging of specific vascular layers of the eye are reviewed. The integration of OCTA in multimodal imaging in the evaluation of retinal vascular occlusive diseases, diabetic retinopathy, uveitis, inherited diseases, age-related macular degeneration, and disorders of the optic nerve is presented. OCTA is an exciting, disruptive technology. Its use is rapidly expanding in clinical practice as well as for research into the pathophysiology of diseases of the posterior pole.
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Affiliation(s)
- Richard F Spaide
- Vitreous, Retina, Macula Consultants of New York, New York, NY, United States.
| | - James G Fujimoto
- Department of Electrical Engineering & Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge MA, United States
| | - Nadia K Waheed
- The Department of Ophthalmology, Tufts University School of Medicine, Boston MA, United States
| | - Srinivas R Sadda
- Doheny Eye Institute, University of California - Los Angeles, Los Angeles, CA, United States
| | - Giovanni Staurenghi
- Eye Clinic, Department of Biomedical and Clinical Sciences "Luigi Sacco", Luigi Sacco Hospital, University of Milan, Milan, Italy
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Braaf B, Donner S, Nam AS, Bouma BE, Vakoc BJ. Complex differential variance angiography with noise-bias correction for optical coherence tomography of the retina. BIOMEDICAL OPTICS EXPRESS 2018; 9:486-506. [PMID: 29552388 PMCID: PMC5854053 DOI: 10.1364/boe.9.000486] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 01/03/2018] [Accepted: 01/03/2018] [Indexed: 05/05/2023]
Abstract
Complex differential variance (CDV) provides phase-sensitive angiographic imaging for optical coherence tomography (OCT) with immunity to phase-instabilities of the imaging system and small-scale axial bulk motion. However, like all angiographic methods, measurement noise can result in erroneous indications of blood flow that confuse the interpretation of angiographic images. In this paper, a modified CDV algorithm that corrects for this noise-bias is presented. This is achieved by normalizing the CDV signal by analytically derived upper and lower limits. The noise-bias corrected CDV algorithm was implemented into an experimental 1 μm wavelength OCT system for retinal imaging that used an eye tracking scanner laser ophthalmoscope at 815 nm for compensation of lateral eye motions. The noise-bias correction improved the CDV imaging of the blood flow in tissue layers with a low signal-to-noise ratio and suppressed false indications of blood flow outside the tissue. In addition, the CDV signal normalization suppressed noise induced by galvanometer scanning errors and small-scale lateral motion. High quality cross-section and motion-corrected en face angiograms of the retina and choroid are presented.
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Affiliation(s)
- Boy Braaf
- Wellman Center for Photomedicine, Massachusetts General Hospital, 50 Blossom St., Boston, Massachusetts 02114, USA
- Harvard Medical School, 25 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Sabine Donner
- Heidelberg Engineering GmbH, Max-Jarecki-Straße 8, 69115 Heidelberg, Germany
| | - Ahhyun S. Nam
- Wellman Center for Photomedicine, Massachusetts General Hospital, 50 Blossom St., Boston, Massachusetts 02114, USA
- Harvard Medical School, 25 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Brett E. Bouma
- Wellman Center for Photomedicine, Massachusetts General Hospital, 50 Blossom St., Boston, Massachusetts 02114, USA
- Harvard Medical School, 25 Shattuck Street, Boston, Massachusetts 02115, USA
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts 02139, USA
| | - Benjamin J. Vakoc
- Wellman Center for Photomedicine, Massachusetts General Hospital, 50 Blossom St., Boston, Massachusetts 02114, USA
- Harvard Medical School, 25 Shattuck Street, Boston, Massachusetts 02115, USA
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts 02139, USA
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Liu G, Yang J, Wang J, Li Y, Zang P, Jia Y, Huang D. Extended axial imaging range, widefield swept source optical coherence tomography angiography. JOURNAL OF BIOPHOTONICS 2017; 10:1464-1472. [PMID: 28493437 PMCID: PMC6145849 DOI: 10.1002/jbio.201600325] [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: 12/22/2016] [Revised: 04/18/2017] [Accepted: 04/19/2017] [Indexed: 05/05/2023]
Abstract
We developed a high-speed, swept source OCT system for widefield OCT angiography (OCTA) imaging. The system has an extended axial imaging range of 6.6 mm. An electrical lens is used for fast, automatic focusing. The recently developed split-spectrum amplitude and phase-gradient angiography allow high-resolution OCTA imaging with only two B-scan repetitions. An improved post-processing algorithm effectively removed trigger jitter artifacts and reduced noise in the flow signal. We demonstrated high contrast 3 mm×3 mm OCTA image with 400×400 pixels acquired in 3 seconds and high-definition 8 mm×6 mm and 12 mm×6 mm OCTA images with 850×400 pixels obtained in 4 seconds. A widefield 8 mm×11 mm OCTA image is produced by montaging two 8 mm×6 mm scans. An ultra-widefield (with a maximum of 22 mm along both vertical and horizontal directions) capillary-resolution OCTA image is obtained by montaging six 12 mm×6 mm scans.
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Affiliation(s)
- Gangjun Liu
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Jianlong Yang
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Jie Wang
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Yan Li
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Pengxiao Zang
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Yali Jia
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, 97239, USA
| | - David Huang
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, 97239, USA
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Rebhun CB, Moult EM, Ploner SB, Neto CM, Alibhai AY, Schottenhamml J, Lee B, Choi W, Rifai FA, Tam MW, Husvogt L, Baumal CR, Witkin AJ, Maier A, Rosenfeld PJ, Duker JS, Fujimoto JG, Waheed NK. Analyzing Relative Blood Flow Speeds in Choroidal Neovascularization Using Variable Interscan Time Analysis OCT Angiography. Ophthalmol Retina 2017; 2:306-319. [PMID: 31047240 DOI: 10.1016/j.oret.2017.08.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 08/08/2017] [Accepted: 08/09/2017] [Indexed: 01/08/2023]
Abstract
PURPOSE Longitudinally visualizing relative blood flow speeds within choroidal neovascularization (CNV) may provide valuable information regarding the evolution of CNV and the response to vascular endothelial growth factor (VEGF) inhibitors. DESIGN Retrospective, longitudinal case series conducted at the New England Eye Center. PARTICIPANTS Patients with either treatment-naïve or previously treated CNV secondary to neovascular age-related macular degeneration. METHODS Optical coherence tomography angiography (OCTA) was performed using a 400-kHz, 1050-nm swept-source OCT system with a 5-repeat B-scan protocol. Variable interscan time analysis (VISTA) was used to compute relative flow speeds from pairs of B-scans having 1.5- and 3.0-ms separations; VISTA signals then were mapped to a color space for display. MAIN OUTCOME MEASURES Quantitative outcomes included OCTA-based area and volume measurements of CNV at initial and follow-up visits. Qualitative outcomes included VISTA OCTA analysis of relative blood flow speeds, along with analysis of contraction, expansion, densification, and rarefication of CNV. RESULTS Seven eyes of 6 patients (4 women and 2 men) with neovascular age-related macular degeneration were evaluated. Two eyes were treatment naïve at the initial visit. Choroidal neovascularization in all eyes at each visit showed relatively higher flow speeds in the trunk, central, and larger vessels and lower flow speed in the small vessels, which generally were located at the periphery of the CNV complex. Overall, the CNV appeared to expand over time despite retention of good visual acuity in all patients. In the treatment-naïve patients, slower-flow-speed vessels contracted with treatment, whereas the larger vessels with higher flow speed remained constant. CONCLUSIONS Variable interscan time analysis OCTA allows for longitudinal observations of relative blood flow speeds in CNV treated with anti-VEGF intravitreal injections. A common finding in this study is that the main trunk and larger vessels seem to have relatively faster blood flow speeds compared with the lesions' peripheral vasculature. Moreover, an overall growth of chronically treated CNV was seen despite retention of good visual acuity. The VISTA framework may prove useful for developing clinical end points, as well as for studying hemodynamics, disease pathogenesis, and treatment response.
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Affiliation(s)
- Carl B Rebhun
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts
| | - Eric M Moult
- Department of Electrical Engineering and Computer Science, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Stefan B Ploner
- Department of Electrical Engineering and Computer Science, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts; Pattern Recognition Laboratory, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | | | - A Yasin Alibhai
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts
| | - Julia Schottenhamml
- Department of Electrical Engineering and Computer Science, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts; Pattern Recognition Laboratory, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Byungkun Lee
- Department of Electrical Engineering and Computer Science, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - WooJhon Choi
- Department of Electrical Engineering and Computer Science, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Fareed A Rifai
- University of South Alabama College of Medicine, Mobile, Alabama
| | - Mary W Tam
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts
| | - Lennart Husvogt
- Department of Electrical Engineering and Computer Science, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts; Pattern Recognition Laboratory, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | | | - Andre J Witkin
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts
| | - Andreas Maier
- Pattern Recognition Laboratory, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | | | - Jay S Duker
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts
| | - James G Fujimoto
- Department of Electrical Engineering and Computer Science, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Nadia K Waheed
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts.
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Poddar R, Migacz JV, Schwartz DM, Werner JS, Gorczynska I. Challenges and advantages in wide-field optical coherence tomography angiography imaging of the human retinal and choroidal vasculature at 1.7-MHz A-scan rate. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:1-14. [PMID: 29090534 PMCID: PMC9062069 DOI: 10.1117/1.jbo.22.10.106018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 10/04/2017] [Indexed: 05/08/2023]
Abstract
We present noninvasive, three-dimensional, depth-resolved imaging of human retinal and choroidal blood circulation with a swept-source optical coherence tomography (OCT) system at 1065-nm center wavelength. Motion contrast OCT imaging was performed with the phase-variance OCT angiography method. A Fourier-domain mode-locked light source was used to enable an imaging rate of 1.7 MHz. We experimentally demonstrate the challenges and advantages of wide-field OCT angiography (OCTA). In the discussion, we consider acquisition time, scanning area, scanning density, and their influence on visualization of selected features of the retinal and choroidal vascular networks. The OCTA imaging was performed with a field of view of 16 deg (5 mm×5 mm) and 30 deg (9 mm×9 mm). Data were presented in en face projections generated from single volumes and in en face projection mosaics generated from up to 4 datasets. OCTA imaging at 1.7 MHz A-scan rate was compared with results obtained from a commercial OCTA instrument and with conventional ophthalmic diagnostic methods: fundus photography, fluorescein, and indocyanine green angiography. Comparison of images obtained from all methods is demonstrated using the same eye of a healthy volunteer. For example, imaging of retinal pathology is presented in three cases of advanced age-related macular degeneration.
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Affiliation(s)
- Raju Poddar
- University of California Davis, Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, Sacramento, California, United States
- Birla Institute of Technology, Department of Bio-Engineering, Mesra, Ranchi, Jharkhand, India
- Address all correspondence to: Raju Poddar, E-mail:
| | - Justin V. Migacz
- University of California Davis, Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, Sacramento, California, United States
| | - Daniel M. Schwartz
- University of California San Francisco, Department of Ophthalmology and Vision Science, San Francisco, California, United States
| | - John S. Werner
- University of California Davis, Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, Sacramento, California, United States
| | - Iwona Gorczynska
- University of California Davis, Vision Science and Advanced Retinal Imaging Laboratory (VSRI), Department of Ophthalmology and Vision Science, Sacramento, California, United States
- Nicolaus Copernicus University, Institute of Physics, Toruń, Poland
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de Boer JF, Leitgeb R, Wojtkowski M. Twenty-five years of optical coherence tomography: the paradigm shift in sensitivity and speed provided by Fourier domain OCT [Invited]. BIOMEDICAL OPTICS EXPRESS 2017; 8:3248-3280. [PMID: 28717565 PMCID: PMC5508826 DOI: 10.1364/boe.8.003248] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 04/26/2017] [Accepted: 05/22/2017] [Indexed: 05/19/2023]
Abstract
Optical coherence tomography (OCT) has become one of the most successful optical technologies implemented in medicine and clinical practice mostly due to the possibility of non-invasive and non-contact imaging by detecting back-scattered light. OCT has gone through a tremendous development over the past 25 years. From its initial inception in 1991 [Science254, 1178 (1991)] it has become an indispensable medical imaging technology in ophthalmology. Also in fields like cardiology and gastro-enterology the technology is envisioned to become a standard of care. A key contributor to the success of OCT has been the sensitivity and speed advantage offered by Fourier domain OCT. In this review paper the development of FD-OCT will be revisited, providing a single comprehensive framework to derive the sensitivity advantage of both SD- and SS-OCT. We point out the key aspects of the physics and the technology that has enabled a more than 2 orders of magnitude increase in sensitivity, and as a consequence an increase in the imaging speed without loss of image quality. This speed increase provided a paradigm shift from point sampling to comprehensive 3D in vivo imaging, whose clinical impact is still actively explored by a large number of researchers worldwide.
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Affiliation(s)
- Johannes F. de Boer
- Department of Physics and Astronomy and LaserLaB Amsterdam, VU University, De Boelelaan 1105, 1081 HV Amsterdam, Department of Ophthalmology, VU Medical Center, Amsterdam, The Netherlands
- Authors are listed in alphabetical order and contributed equally
| | - Rainer Leitgeb
- Christian Doppler Laboratory OPTRAMED, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
- Authors are listed in alphabetical order and contributed equally
| | - Maciej Wojtkowski
- Physical Optics and Biophotonics Group, Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52 01-224 Warsaw, Poland
- Authors are listed in alphabetical order and contributed equally
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SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY REVEALS CHORIOCAPILLARIS ALTERATIONS IN EYES WITH NASCENT GEOGRAPHIC ATROPHY AND DRUSEN-ASSOCIATED GEOGRAPHIC ATROPHY. Retina 2017; 36 Suppl 1:S2-S11. [PMID: 28005659 DOI: 10.1097/iae.0000000000001287] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
PURPOSE To investigate choriocapillaris (CC) alteration in patients with nascent geographic atrophy (nGA) and/or drusen-associated geographic atrophy (DAGA) using swept-source optical coherence tomography angiography (OCTA). METHODS A 1,050-nm wavelength, 400 kHz A-scan rate swept-source optical coherence tomography prototype was used to perform volumetric swept-source optical coherence tomography angiography over 6 mm × 6 mm fields of view in patients with nGA and/or DAGA. The resulting optical coherence tomography (OCT) and OCTA data were analyzed using a combination of en face and cross-sectional techniques. Variable interscan time analysis (VISTA) was used to differentiate CC flow impairment from complete CC atrophy. RESULTS A total of 7 eyes from 6 patients (mean age: 73.8 ± 5.7 years) were scanned. Seven areas of nGA and three areas of DAGA were identified. Analysis of cross-sectional OCT and OCTA images identified focal alterations of the CC underlying all seven areas of nGA and all three areas of DAGA. En face OCTA analysis of the CC revealed diffuse CC alterations in all eyes. Variable interscan time analysis processing suggested that the observed CC flow alterations predominantly corresponded to flow impairment rather than complete CC atrophy. CONCLUSION The OCTA imaging of the CC revealed focal CC flow impairment associated with areas of nGA and DAGA, as well as diffuse CC flow impairment throughout the imaged field. En face OCT analysis should prove useful for understanding the pathogenesis of nGA and DAGA and for identifying the formation of nGA and DAGA as endpoints in therapeutic trials.
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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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Salas M, Augustin M, Ginner L, Kumar A, Baumann B, Leitgeb R, Drexler W, Prager S, Hafner J, Schmidt-Erfurth U, Pircher M. Visualization of micro-capillaries using optical coherence tomography angiography with and without adaptive optics. BIOMEDICAL OPTICS EXPRESS 2017; 8:207-222. [PMID: 28101412 PMCID: PMC5231293 DOI: 10.1364/boe.8.000207] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 11/10/2016] [Accepted: 12/06/2016] [Indexed: 05/18/2023]
Abstract
The purpose of this work is to investigate the benefits of adaptive optics (AO) technology for optical coherence tomography angiography (OCTA). OCTA has shown great potential in non-invasively enhancing the contrast of vessels and small capillaries. Especially the capability of the technique to visualize capillaries with a lateral extension that is below the transverse resolution of the system opens unique opportunities in diagnosing retinal vascular diseases. However, there are some limitations of this technology such as shadowing and projection artifacts caused by overlying vasculature or the inability to determine the true extension of a vessel. Thus, the evaluation of the vascular structure and density based on OCTA alone can be misleading. In this paper we compare the performance of AO-OCT, AO-OCTA and OCTA for imaging retinal vasculature. The improved transverse resolution and the reduced depth of focus of AO-OCT and AO-OCTA greatly reduce shadowing artifacts allowing for a better differentiation and segmentation of different vasculature layers of the inner retina. The comparison is done on images recorded in healthy volunteers and in diabetic patients with distinct pathologies of the retinal microvasculature.
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Affiliation(s)
- Matthias Salas
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Marco Augustin
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Laurin Ginner
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
- Christian Doppler Laboratory for Innovative Optical Imaging and Its Translation to Medicine, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Abhishek Kumar
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Bernhard Baumann
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Rainer Leitgeb
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
- Christian Doppler Laboratory for Innovative Optical Imaging and Its Translation to Medicine, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Wolfgang Drexler
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Sonja Prager
- Department of Ophthalmology and Optometry, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Julia Hafner
- Department of Ophthalmology and Optometry, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Ursula Schmidt-Erfurth
- Department of Ophthalmology and Optometry, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Michael Pircher
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
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Cabrera DeBuc D, Somfai GM, Koller A. Retinal microvascular network alterations: potential biomarkers of cerebrovascular and neural diseases. Am J Physiol Heart Circ Physiol 2016; 312:H201-H212. [PMID: 27923786 DOI: 10.1152/ajpheart.00201.2016] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 11/04/2016] [Accepted: 11/11/2016] [Indexed: 12/12/2022]
Abstract
Increasing evidence suggests that the conditions of retinal microvessels are indicators to a variety of cerebrovascular, neurodegenerative, psychiatric, and developmental diseases. Thus noninvasive visualization of the human retinal microcirculation offers an exceptional opportunity for the investigation of not only the retinal but also cerebral microvasculature. In this review, we show how the conditions of the retinal microvessels could be used to assess the conditions of brain microvessels because the microvascular network of the retina and brain share, in many aspects, standard features in development, morphology, function, and pathophysiology. Recent techniques and imaging modalities, such as optical coherence tomography (OCT), allow more precise visualization of various layers of the retina and its microcirculation, providing a "microscope" to brain microvessels. We also review the potential role of retinal microvessels in the risk identification of cerebrovascular and neurodegenerative diseases. The association between vision problems and cerebrovascular and neurodegenerative diseases, as well as the possible role of retinal microvascular imaging biomarkers in cerebrovascular and neurodegenerative screening, their potentials, and limitations, are also discussed.
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Affiliation(s)
- Delia Cabrera DeBuc
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida;
| | - Gabor Mark Somfai
- Semmelweis University, Budapest, Hungary.,Augenzentrum, Pallas Kliniken, Olten, Switzerland
| | - Akos Koller
- Institute of Natural Sciences, University of Physical Education, Budapest, Hungary; and.,Department of Physiology, New York Medical College, Valhalla, New York
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41
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Merkle CW, Leahy C, Srinivasan VJ. Dynamic contrast optical coherence tomography images transit time and quantifies microvascular plasma volume and flow in the retina and choriocapillaris. BIOMEDICAL OPTICS EXPRESS 2016; 7:4289-4312. [PMID: 27867732 PMCID: PMC5102529 DOI: 10.1364/boe.7.004289] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 08/19/2016] [Accepted: 09/16/2016] [Indexed: 05/18/2023]
Abstract
Despite the prevalence of optical imaging techniques to measure hemodynamics in large retinal vessels, quantitative measurements of retinal capillary and choroidal hemodynamics have traditionally been challenging. Here, a new imaging technique called dynamic contrast optical coherence tomography (DyC-OCT) is applied in the rat eye to study microvascular blood flow in individual retinal and choroidal layers in vivo. DyC-OCT is based on imaging the transit of an intravascular tracer dynamically as it passes through the field-of-view. Hemodynamic parameters can be determined through quantitative analysis of tracer kinetics. In addition to enabling depth-resolved transit time, volume, and flow measurements, the injected tracer also enhances OCT angiograms and enables clear visualization of the choriocapillaris, particularly when combined with a post-processing method for vessel enhancement. DyC-OCT complements conventional OCT angiography through quantification of tracer dynamics, similar to fluorescence angiography, but with the important added benefit of laminar resolution.
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Affiliation(s)
- Conrad W. Merkle
- Department of Biomedical Engineering, University of California Davis, Davis, California, USA
| | - Conor Leahy
- Department of Biomedical Engineering, University of California Davis, Davis, California, USA
| | - Vivek J. Srinivasan
- Department of Biomedical Engineering, University of California Davis, Davis, California, USA
- Department of Ophthalmology and Vision Science, University of California Davis School of Medicine, Sacramento, California, USA
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Liu G, Jia Y, Pechauer AD, Chandwani R, Huang D. Split-spectrum phase-gradient optical coherence tomography angiography. BIOMEDICAL OPTICS EXPRESS 2016; 7:2943-54. [PMID: 27570689 PMCID: PMC4986805 DOI: 10.1364/boe.7.002943] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 06/28/2016] [Accepted: 07/05/2016] [Indexed: 05/20/2023]
Abstract
A phase gradient angiography (PGA) method is proposed for optical coherence tomography (OCT). This method allows the use of phase information to map the microvasculature in tissue without the correction of bulk motion and laser trigger jitter induced phase artifacts. PGA can also be combined with the amplitude/intensity to improve the performance. Split-spectrum technique can further increase the signal to noise ratio by more than two times. In-vivo imaging of human retinal circulation is shown with a 70 kHz, 840 nm spectral domain OCT system and a 200 kHz, 1050 nm swept source OCT system. Four different OCT angiography methods are compared. The best performance was achieved with split-spectrum amplitude and phase-gradient angiography.
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43
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Chu Z, Lin J, Gao C, Xin C, Zhang Q, Chen CL, Roisman L, Gregori G, Rosenfeld PJ, Wang RK. Quantitative assessment of the retinal microvasculature using optical coherence tomography angiography. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:66008. [PMID: 27286188 PMCID: PMC4901200 DOI: 10.1117/1.jbo.21.6.066008] [Citation(s) in RCA: 196] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 05/26/2016] [Indexed: 05/18/2023]
Abstract
Optical coherence tomography angiography (OCTA) is clinically useful for the qualitative assessment of the macular microvasculature. However, there is a need for comprehensive quantitative tools to help objectively analyze the OCT angiograms. Few studies have reported the use of a single quantitative index to describe vessel density in OCT angiograms. In this study, we introduce a five-index quantitative analysis of OCT angiograms in an attempt to detect and assess vascular abnormalities from multiple perspectives. The indices include vessel area density, vessel skeleton density, vessel diameter index, vessel perimeter index, and vessel complexity index. We show the usefulness of the proposed indices with five illustrative cases. Repeatability is tested on both a healthy case and a stable diseased case, giving interclass coefficients smaller than 0.031. The results demonstrate that our proposed quantitative analysis may be useful as a complement to conventional OCTA for the diagnosis of disease and monitoring of treatment.
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Affiliation(s)
- Zhongdi Chu
- University of Washington, Department of Bioengineering, 3720 Northeast 15th Avenue, Seattle, Washington 98006, United States
| | - Jason Lin
- University of Washington, Department of Bioengineering, 3720 Northeast 15th Avenue, Seattle, Washington 98006, United States
| | - Chen Gao
- University of Washington, Department of Bioengineering, 3720 Northeast 15th Avenue, Seattle, Washington 98006, United States
| | - Chen Xin
- University of Washington, Department of Bioengineering, 3720 Northeast 15th Avenue, Seattle, Washington 98006, United States
| | - Qinqin Zhang
- University of Washington, Department of Bioengineering, 3720 Northeast 15th Avenue, Seattle, Washington 98006, United States
| | - Chieh-Li Chen
- University of Washington, Department of Bioengineering, 3720 Northeast 15th Avenue, Seattle, Washington 98006, United States
| | - Luis Roisman
- University of Miami Miller School of Medicine, Bascom Palmer Eye Institute, 900 Northeast 17th Street, Miami, Florida 33136, United States
| | - Giovanni Gregori
- University of Miami Miller School of Medicine, Bascom Palmer Eye Institute, 900 Northeast 17th Street, Miami, Florida 33136, United States
| | - Philip J. Rosenfeld
- University of Miami Miller School of Medicine, Bascom Palmer Eye Institute, 900 Northeast 17th Street, Miami, Florida 33136, United States
| | - Ruikang K. Wang
- University of Washington, Department of Bioengineering, 3720 Northeast 15th Avenue, Seattle, Washington 98006, United States
- Address all correspondence to: Ruikang K. Wang, E-mail:
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Gorczynska I, Migacz JV, Zawadzki RJ, Capps AG, Werner JS. Comparison of amplitude-decorrelation, speckle-variance and phase-variance OCT angiography methods for imaging the human retina and choroid. BIOMEDICAL OPTICS EXPRESS 2016; 7:911-42. [PMID: 27231598 PMCID: PMC4866465 DOI: 10.1364/boe.7.000911] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 02/03/2016] [Accepted: 02/12/2016] [Indexed: 05/18/2023]
Abstract
We compared the performance of three OCT angiography (OCTA) methods: speckle variance, amplitude decorrelation and phase variance for imaging of the human retina and choroid. Two averaging methods, split spectrum and volume averaging, were compared to assess the quality of the OCTA vascular images. All data were acquired using a swept-source OCT system at 1040 nm central wavelength, operating at 100,000 A-scans/s. We performed a quantitative comparison using a contrast-to-noise (CNR) metric to assess the capability of the three methods to visualize the choriocapillaris layer. For evaluation of the static tissue noise suppression in OCTA images we proposed to calculate CNR between the photoreceptor/RPE complex and the choriocapillaris layer. Finally, we demonstrated that implementation of intensity-based OCT imaging and OCT angiography methods allows for visualization of retinal and choroidal vascular layers known from anatomic studies in retinal preparations. OCT projection imaging of data flattened to selected retinal layers was implemented to visualize retinal and choroidal vasculature. User guided vessel tracing was applied to segment the retinal vasculature. The results were visualized in a form of a skeletonized 3D model.
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Affiliation(s)
- Iwona Gorczynska
- Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA 95817, USA
- Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun 87-100, Poland
| | - Justin V. Migacz
- Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA 95817, USA
| | - Robert J. Zawadzki
- Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA 95817, USA
| | - Arlie G. Capps
- Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA 95817, USA
- Physics Division, Lawrence Livermore National Laboratory Livermore, CA 94550, USA
| | - John S. Werner
- Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA 95817, USA
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Varga BE, Gao W, Laurik KL, Tátrai E, Simó M, Somfai GM, Cabrera DeBuc D. Investigating Tissue Optical Properties and Texture Descriptors of the Retina in Patients with Multiple Sclerosis. PLoS One 2015; 10:e0143711. [PMID: 26619298 PMCID: PMC4664388 DOI: 10.1371/journal.pone.0143711] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 11/09/2015] [Indexed: 01/30/2023] Open
Abstract
Purpose To assess the differences in texture descriptors and optical properties of retinal tissue layers in patients with multiple sclerosis (MS) and to evaluate their usefulness in the detection of neurodegenerative changes using optical coherence tomography (OCT) image segmentation. Patients and Methods 38 patients with MS were examined using Stratus OCT. The raw macular OCT data were exported and processed using OCTRIMA software. The enrolled eyes were divided into two groups, based on the presence of optic neuritis (ON) in the history (MSON+ group, n = 36 and MSON- group, n = 31). Data of 29 eyes of 24 healthy subjects (H) were used as controls. A total of seven intraretinal layers were segmented and thickness as well as optical parameters such as contrast, fractal dimension, layer index and total reflectance were measured. Mixed-model ANOVA analysis was used for statistical comparisons. Results Significant thinning of the retinal nerve fiber layer (RNFL), ganglion cell/inner plexiform layer complex (GCL+IPL) and ganglion cell complex (GCC, RNFL+GCL+IPL) was observed between study groups in all comparisons. Significant difference was found in contrast in the RNFL, GCL+IPL, GCC, inner nuclear layer (INL) and outer plexiform layer when comparing MSON+ to the other groups. Higher fractal dimension values were observed in GCL+IPL and INL layers when comparing H vs. MSON+ groups. A significant difference was found in layer index in the RNFL, GCL+IPL and GCC layers in all comparisons. A significant difference was observed in total reflectance in the RNFL, GCL+IPL and GCC layers between the three examination groups. Conclusion Texture and optical properties of the retinal tissue undergo pronounced changes in MS even without optic neuritis. Our results may help to further improve the diagnostic efficacy of OCT in MS and neurodegeneration.
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Affiliation(s)
- Boglárka Enikő Varga
- Department of Ophthalmology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Wei Gao
- Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, Florida, United States of America
| | - Kornélia Lenke Laurik
- Department of Ophthalmology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Erika Tátrai
- Department of Ophthalmology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Magdolna Simó
- Department of Neurology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Gábor Márk Somfai
- Department of Ophthalmology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
- Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, Florida, United States of America
| | - Delia Cabrera DeBuc
- Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, Florida, United States of America
- * E-mail:
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Amarakoon S, de Jong JH, Braaf B, Yzer S, Missotten T, van Velthoven MEJ, de Boer JF. Phase-Resolved Doppler Optical Coherence Tomographic Features in Retinal Angiomatous Proliferation. Am J Ophthalmol 2015. [PMID: 26210860 DOI: 10.1016/j.ajo.2015.07.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE To study patients diagnosed with retinal angiomatous proliferation (RAP) based on conventional imaging techniques with phase-resolved Doppler optical coherence tomography (OCT) to detect and localize blood flow in RAP lesions; and to compare these findings to conventional imaging, which are mostly invasive and give limited information concerning intra- and transretinal blood flow. DESIGN Single-center, consecutive observational case series. METHODS Twelve treatment-naïve patients diagnosed with RAP based on fundus examination, fluorescein angiography, and indocyanine green angiography were included. Median age was 79 years (range 65-90). Patients were imaged with an experimental 1040 nm swept-source phase-resolved Doppler OCT instrument. Abnormal flow was defined as intraretinal neovascularization or retinal choroidal anastomosis. RESULTS In 11 patients adequate phase-resolved Doppler OCT images were obtained showing abnormal blood flow in the RAP lesion. In 4 patients a retinal choroidal anastomosis was found, 3 patients showed intraretinal neovascularization connected with a pigment epithelial detachment, 2 patients showed only intraretinal neovascularization, and in 2 patients flow was limited to the subretinal or sub-retinal pigment epithelial space. CONCLUSIONS Phase-resolved Doppler OCT is able to detect and localize abnormal blood flow within RAP lesions. Blood flow was mostly confined to the intraretinal structures with or without a connecting pigment epithelial detachment; in one-third of patients a retinal choroidal anastomosis was detected. The potential of angiography with phase-resolved Doppler OCT to accurately distinguish between normal and pathologic blood flow in addition to structural OCT data without invasive procedures will help to further elucidate both retinal and choroidal vascular pathologies like RAP.
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Affiliation(s)
- Sankha Amarakoon
- Rotterdam Ophthalmic Institute, Rotterdam, Netherlands; Medical Retina Service, Rotterdam Eye Hospital, Rotterdam, Netherlands
| | - Jan H de Jong
- Rotterdam Ophthalmic Institute, Rotterdam, Netherlands
| | - Boy Braaf
- Rotterdam Ophthalmic Institute, Rotterdam, Netherlands
| | - Suzanne Yzer
- Medical Retina Service, Rotterdam Eye Hospital, Rotterdam, Netherlands
| | - Tom Missotten
- Rotterdam Ophthalmic Institute, Rotterdam, Netherlands; Medical Retina Service, Rotterdam Eye Hospital, Rotterdam, Netherlands
| | - Mirjam E J van Velthoven
- Rotterdam Ophthalmic Institute, Rotterdam, Netherlands; Medical Retina Service, Rotterdam Eye Hospital, Rotterdam, Netherlands.
| | - Johannes F de Boer
- Rotterdam Ophthalmic Institute, Rotterdam, Netherlands; Institute for Lasers, Life and Biophotonics Amsterdam, Department of Physics and Astronomy, VU University, Amsterdam, Netherlands
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Ruminski D, Sikorski BL, Bukowska D, Szkulmowski M, Krawiec K, Malukiewicz G, Bieganowski L, Wojtkowski M. OCT angiography by absolute intensity difference applied to normal and diseased human retinas. BIOMEDICAL OPTICS EXPRESS 2015; 6:2738-54. [PMID: 26309740 PMCID: PMC4541504 DOI: 10.1364/boe.6.002738] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/30/2015] [Accepted: 06/30/2015] [Indexed: 05/22/2023]
Abstract
We compare four optical coherence tomography techniques for noninvasive visualization of microcapillary network in the human retina and murine cortex. We perform phantom studies to investigate contrast-to-noise ratio for angiographic images obtained with each of the algorithm. We show that the computationally simplest absolute intensity difference angiographic OCT algorithm that bases only on two cross-sectional intensity images may be successfully used in clinical study of healthy eyes and eyes with diabetic maculopathy and branch retinal vein occlusion.
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Affiliation(s)
- Daniel Ruminski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100 Torun, Poland
- both authors contributed equally
| | - Bartosz L. Sikorski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100 Torun, Poland
- Department of Ophthalmology, Nicolaus Copernicus University, 9 M. Sklodowskiej-Curie St., 85-094 Bydgoszcz, Poland
- both authors contributed equally
| | - Danuta Bukowska
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100 Torun, Poland
| | - Maciej Szkulmowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100 Torun, Poland
| | - Krzysztof Krawiec
- Laboratory of Intelligent Decision Support Systems, Poznan University of Technology, Piotrowo 2, 60-965 Poznań, Poland
| | - Grazyna Malukiewicz
- Department of Ophthalmology, Nicolaus Copernicus University, 9 M. Sklodowskiej-Curie St., 85-094 Bydgoszcz, Poland
| | - Lech Bieganowski
- Collegium Medicum, Nicolaus Copernicus University in Torun, Jagiellońska 13-15, 85-067 Bydgoszcz, Poland
| | - Maciej Wojtkowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100 Torun, Poland
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48
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Lozzi A, Agrawal A, Boretsky A, Welle CG, Hammer DX. Image quality metrics for optical coherence angiography. BIOMEDICAL OPTICS EXPRESS 2015; 6:2435-2447. [PMID: 26203372 PMCID: PMC4505700 DOI: 10.1364/boe.6.002435] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 05/13/2015] [Accepted: 06/09/2015] [Indexed: 05/20/2023]
Abstract
We characterized image quality in optical coherence angiography (OCA) en face planes of mouse cortical capillary network in terms of signal-to-noise ratio (SNR) and Weber contrast (Wc) through a novel mask-based segmentation method. The method was used to compare two adjacent B-scan processing algorithms, (1) average absolute difference (AAD) and (2) standard deviation (SD), while varying the number of lateral cross-sections acquired (also known as the gate length, N). AAD and SD are identical at N = 2 and exhibited similar image quality for N<10. However, AAD is relatively less susceptible to bulk tissue motion artifact than SD. SNR and Wc were 15% and 35% higher for AAD from N = 25 to 100. In addition data sets were acquired with two objective lenses with different magnifications to quantify the effect of lateral resolution on fine capillary detection. The lower power objective yielded a significant mean broadening of 17% in Full Width Half Maximum (FWHM) diameter. These results may guide study and device designs for OCA capillary and blood flow quantification.
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Affiliation(s)
- Andrea Lozzi
- Center for Devices and Radiological Health, Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring MD 20993, USA
| | - Anant Agrawal
- Center for Devices and Radiological Health, Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring MD 20993, USA
| | - Adam Boretsky
- Center for Devices and Radiological Health, Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring MD 20993, USA
| | - Cristin G. Welle
- Center for Devices and Radiological Health, Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring MD 20993, USA
| | - Daniel X. Hammer
- Center for Devices and Radiological Health, Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring MD 20993, USA
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Duma VF, Tankam P, Huang J, Won J, Rolland JP. Optimization of galvanometer scanning for optical coherence tomography. APPLIED OPTICS 2015; 54:5495-507. [PMID: 26192852 DOI: 10.1364/ao.54.005495] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We study experimentally the effective duty cycle of galvanometer-based scanners (GSs) with regard to three main parameters of the scanning process: theoretical/imposed duty cycle (of the input signal), scan frequency, and scan amplitude. Sawtooth and triangular input signals for the device are considered. The effects of the mechanical inertia of the oscillatory element of the GS are analyzed and their consequences are discussed in the context of optical coherence tomography (OCT) imaging. When the theoretical duty cycle and the scan amplitude are increased to the limit, the saturation of the device is demonstrated for a useful range of scan frequencies by direct measurement of the position of the galvomirror. Investigations of OCT imaging of large samples also validate this saturation, as examplified by the gaps/blurred portions obtained between neighboring images when using both triangular and sawtooth scanning at high scan frequencies. For this latter aspect, the necessary overlap between neighboring B-scans, and therefore between the corresponding volumetric reconstructions of the sample, are evaluated and implemented with regard to the same parameters of the scanning process. OCT images that are free of these artifacts are thus obtained.
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50
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Zhang Q, Huang Y, Zhang T, Kubach S, An L, Laron M, Sharma U, Wang RK. Wide-field imaging of retinal vasculature using optical coherence tomography-based microangiography provided by motion tracking. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:066008. [PMID: 26102573 PMCID: PMC4478052 DOI: 10.1117/1.jbo.20.6.066008] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 05/28/2015] [Indexed: 05/18/2023]
Abstract
Optical coherence tomography (OCT)-based optical microangiography (OMAG) is a high-resolution, noninvasive imaging technique capable of providing three-dimensional in vivo blood flow visualization within microcirculatory tissue beds in the eye. Although the technique has demonstrated early clinical utility by imaging diseased eyes, its limited field of view (FOV) and the sensitivity to eye motion remain the two biggest challenges for the widespread clinical use of the technology. Here, we report the results of retinal OMAG imaging obtained from a Zeiss Cirrus 5000 spectral domain OCT system with motion tracking capability achieved by a line scan ophthalmoscope (LSO). The tracking LSO is able to guide the OCT scanning, which minimizes the effect of eye motion in the final results. We show that the tracking can effectively correct the motion artifacts and remove the discontinuities and distortions of vascular appearance due to microsaccade, leading to almost motion-free OMAG angiograms with good repeatability and reliability. Due to the robustness of the tracking LSO, we also show the montage scan protocol to provide unprecedented wide field retinal OMAG angiograms. We experimentally demonstrate a 12 x 16 mm² retinal OMAG angiogram acquired from a volunteer, which is the widest FOV retinal vasculature imaging up to now in the community.
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Affiliation(s)
- Qinqin Zhang
- University of Washington, Department of Bioengineering, 3720 NE 15th Avenue, Seattle, Washington 98195, United States
| | - Yanping Huang
- University of Washington, Department of Bioengineering, 3720 NE 15th Avenue, Seattle, Washington 98195, United States
| | - Thomas Zhang
- Carl Zeiss Meditec, Inc., 5160 Hacienda Drive, Dublin, California 94568, United States
| | - Sophie Kubach
- Carl Zeiss Meditec, Inc., 5160 Hacienda Drive, Dublin, California 94568, United States
| | - Lin An
- Carl Zeiss Meditec, Inc., 5160 Hacienda Drive, Dublin, California 94568, United States
| | - Michal Laron
- Carl Zeiss Meditec, Inc., 5160 Hacienda Drive, Dublin, California 94568, United States
| | - Utkarsh Sharma
- Carl Zeiss Meditec, Inc., 5160 Hacienda Drive, Dublin, California 94568, United States
| | - Ruikang K. Wang
- University of Washington, Department of Bioengineering, 3720 NE 15th Avenue, Seattle, Washington 98195, United States
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