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Kolář R, Odstrčilík J, Tornow RP. Photoplethysmographic analysis of retinal videodata based on the Fourier domain approach. BIOMEDICAL OPTICS EXPRESS 2021; 12:7405-7421. [PMID: 35003842 PMCID: PMC8713668 DOI: 10.1364/boe.441451] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/22/2021] [Accepted: 10/22/2021] [Indexed: 05/23/2023]
Abstract
Assessment of retinal blood flow inside the optic nerve head (ONH) and the peripapillary area is an important task in retinal imaging. For this purpose, an experimental binocular video ophthalmoscope that acquires precisely synchronized video sequences of the optic nerve head and peripapillary area from both eyes has been previously developed. It enables to compare specific characteristics of both eyes and efficiently detect the eye asymmetry. In this paper, we describe a novel methodology for the analysis of acquired video data using a photoplethysmographic approach. We describe and calculate the pulsatile attenuation amplitude (PAA) spatial map, which quantifies the maximum relative change of blood volume during a cardiac cycle using a frequency domain approach. We also describe in detail the origin of PAA maps from the fundamental (the first) and the second harmonic component of the pulsatile signal, and we compare the results obtained by time-based and frequency-based approaches. In several cases, we show the advantages and possibilities of this device and the appropriate image analysis approach - fast measurement and comparison of blood flow characteristics of both eyes at a glance, the robustness of this approach, and the possibility of easy detection of asymmetry.
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Affiliation(s)
- Radim Kolář
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, 616 00 Brno, Czech Republic
| | - Jan Odstrčilík
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, 616 00 Brno, Czech Republic
| | - Ralf-Peter Tornow
- Department of Ophthalmology, Friedrich-Alexander-University of Erlangen-Nuremberg, 91056 Erlangen, Germany
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2
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Retinal blood flow reversal quantitatively monitored in out-of-plane vessels with laser Doppler holography. Sci Rep 2021; 11:17828. [PMID: 34497299 PMCID: PMC8426375 DOI: 10.1038/s41598-021-96877-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 08/05/2021] [Indexed: 12/29/2022] Open
Abstract
Laser Doppler holography is a planar blood flow imaging technique recently introduced in ophthalmology to image human retinal and choroidal blood flow non-invasively. Here we present a digital method based on the Doppler spectrum asymmetry that reveals the local direction of blood flow with respect to the optical axis in out-of-plane vessels. This directional information is overlaid on standard grayscale blood flow images to depict flow moving towards the camera in red and flow moving away from the camera in blue, as in ultrasound color Doppler imaging. We show that thanks to the strong contribution of backscattering to the Doppler spectrum in out-of-plane vessels, the local axial direction of blood flow can be revealed with a high temporal resolution, which enables us to evidence pathological blood flow reversals. We also demonstrate the use of optical Doppler spectrograms to quantitatively monitor retinal blood flow reversals.
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3
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Szegedi S, Hommer N, Kallab M, Puchner S, Schmidl D, Werkmeister RM, Garhöfer G, Schmetterer L. Repeatability and Reproducibility of Total Retinal Blood Flow Measurements Using Bi-Directional Doppler OCT. Transl Vis Sci Technol 2020; 9:34. [PMID: 32832239 PMCID: PMC7414639 DOI: 10.1167/tvst.9.7.34] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 04/28/2020] [Indexed: 12/01/2022] Open
Abstract
Purpose To investigate the repeatability and reproducibility of total retinal blood flow measurements using a custom-built dual-beam bidirectional Doppler optical coherence tomography (OCT) system in healthy subjects. Methods Repeatability and reproducibility were analyzed in 10 and 34 healthy subjects, respectively. For repeatability, measurements were taken twice within 30 minutes, for reproducibility, twice within two to five weeks. Two analysis approaches were compared for calculation of absolute blood velocities: a previously published approach resulting in values for total arterial (QA,abs) and total venous blood flow (QV,abs) and a novel approach taking into account that there is a fixed relation between the phase shift in the two OCT channels (QA,new, QV,new). Repeatability and reproducibility were quantified using intraclass correlation coefficients (ICCs). Results For QA,abs and QV,abs, ICC values between 0.78 and 0.84 were obtained. QA,new and QV,new values revealed better repeatability and reproducibility as compared to the convential appoach. Repeatability ICCs for QA,new and QV,new were between 0.91 and 0.93, and reproducibility ICCs were between 0.87 and 0.91 indicating excellent reproducibility. Good agreement was observed between total retinal blood flow values as measured from retinal arteries and retinal veins. Conclusions Measurement of total retinal blood flow using dual-beam Doppler OCT shows excellent reproducibility, which can further be improved by using a novel algorithm for calculating blood velocities in retinal vessels. Translational Relevance Our data indicate that dual-beam Doppler OCT can be used for longitudinal studies. Hence, quantitative retinal blood flow may be established as a biomarker for progression vascular eye diseases.
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Affiliation(s)
- Stephan Szegedi
- Department of Clinical Pharmacology, Medical University of Vienna, Austria
| | - Nikolaus Hommer
- Department of Clinical Pharmacology, Medical University of Vienna, Austria
| | - Martin Kallab
- Department of Clinical Pharmacology, Medical University of Vienna, Austria
| | - Stefan Puchner
- Department of Clinical Pharmacology, Medical University of Vienna, Austria.,Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria
| | - Doreen Schmidl
- Department of Clinical Pharmacology, Medical University of Vienna, Austria
| | - René M Werkmeister
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology, Medical University of Vienna, Austria
| | - Leopold Schmetterer
- Department of Clinical Pharmacology, Medical University of Vienna, Austria.,Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria.,Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.,School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore.,SERI-NTU Advanced Ocular Engineering (STANCE), Singapore.,Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore.,Institute of Clinical and Experimental Ophthalmology, Basel, Switzerland
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4
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Desissaire S, Schwarzhans F, Salas M, Wartak A, Fischer G, Vass C, Pircher M, Hitzenberger CK. Analysis of longitudinal sections of retinal vessels using Doppler OCT. BIOMEDICAL OPTICS EXPRESS 2020; 11:1772-1789. [PMID: 32341847 PMCID: PMC7173918 DOI: 10.1364/boe.385938] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 02/21/2020] [Accepted: 02/21/2020] [Indexed: 05/12/2023]
Abstract
We present a new method for imaging retinal vessels that provides both structural and hemodynamic information. Our technique is based on a single beam OCT system with an integrated retinal tracker that enables recording of arbitrary scan patterns. We record longitudinal sections along the traces of retinal vessels. The tracker function enables the acquisition of multiple longitudinal sections along the same trace to provide high-quality averaged OCT scans as well as temporal changes of flow dynamics. The vessel walls are clearly identified as narrow, bright lines from which the vessel diameter can be retrieved as a function of position along the vessel. Furthermore, the Doppler angle can be obtained at each position along the vessel trace, enabling measurement of absolute blood flow by Doppler OCT analysis. The method is demonstrated in flow phantoms and in-vivo on retinal vessel bifurcations in healthy volunteers. In 7 of 9 imaged bifurcations, measured in- and outflow deviate by less than 11%, demonstrating the consistency of the method.
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Affiliation(s)
- Sylvia Desissaire
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, 1090, Austria
| | - Florian Schwarzhans
- Institute of Medical Information Management, Medical University of Vienna, Vienna, 1090, Austria
| | - Matthias Salas
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, 1090, Austria
| | - Andreas Wartak
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, 1090, Austria
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - Georg Fischer
- Institute of Medical Information Management, Medical University of Vienna, Vienna, 1090, Austria
| | - Clemens Vass
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, 1090, Austria
| | - Michael Pircher
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, 1090, Austria
| | - Christoph K. Hitzenberger
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, 1090, Austria
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5
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Pijewska E, Sylwestrzak M, Gorczynska I, Tamborski S, Pawlak MA, Szkulmowski M. Blood flow rate estimation in optic disc capillaries and vessels using Doppler optical coherence tomography with 3D fast phase unwrapping. BIOMEDICAL OPTICS EXPRESS 2020; 11:1336-1353. [PMID: 32206414 PMCID: PMC7075620 DOI: 10.1364/boe.382155] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/13/2020] [Accepted: 01/24/2020] [Indexed: 05/25/2023]
Abstract
The retinal volumetric flow rate contains useful information not only for ophthalmology but also for the diagnosis of common civilization diseases such as diabetes, Alzheimer's disease, or cerebrovascular diseases. Non-invasive optical methods for quantitative flow assessment, such as Doppler optical coherence tomography (OCT), have certain limitations. One is the phase wrapping that makes simultaneous calculations of the flow in all human retinal vessels impossible due to a very large span of flow velocities. We demonstrate that three-dimensional Doppler OCT combined with three-dimensional four Fourier transform fast phase unwrapping (3D 4FT FPU) allows for the calculation of the volumetric blood flow rate in real-time by the implementation of the algorithms in a graphics processing unit (GPU). The additive character of the flow at the furcations is proven using a microfluidic device with controlled flow rates as well as in the retinal veins bifurcations imaged in the optic disc area of five healthy volunteers. We show values of blood flow rates calculated for retinal capillaries and vessels with diameters in the range of 12-150 µm. The potential of quantitative measurement of retinal blood flow volume includes noninvasive detection of carotid artery stenosis or occlusion, measuring vascular reactivity and evaluation of vessel wall stiffness.
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Affiliation(s)
- Ewelina Pijewska
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziądzka 5, 87-100 Torun, Poland
| | - Marcin Sylwestrzak
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziądzka 5, 87-100 Torun, Poland
| | - Iwona Gorczynska
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziądzka 5, 87-100 Torun, Poland
| | - Szymon Tamborski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziądzka 5, 87-100 Torun, Poland
| | - Mikolaj A. Pawlak
- Department of Neurology and Cerebrovascular Disorders, Poznan University of Medical Sciences, Fredry 10, 61-701 Poznań, Poland
- Department of Clinical Genetics, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Maciej Szkulmowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziądzka 5, 87-100 Torun, Poland
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6
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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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7
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Shi W, Chen C, Jivraj J, Dobashi Y, Gao W, Yang VX. 2D MEMS-based high-speed beam-shifting technique for speckle noise reduction and flow rate measurement in optical coherence tomography. OPTICS EXPRESS 2019; 27:12551-12564. [PMID: 31052795 DOI: 10.1364/oe.27.012551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 04/01/2019] [Indexed: 06/09/2023]
Abstract
In this manuscript, a two-dimensional (2D) micro-electro-mechanical system (MEMS)-based, high-speed beam-shifting spectral domain optical coherence tomography (MHB-SDOCT) is proposed for speckle noise reduction and absolute flow rate measurement. By combining a zigzag scanning protocol, the frame rates of 45.2 Hz for speckle reduction and 25.6 Hz for flow rate measurement are achieved for in-vivo tissue imaging. Phantom experimental results have shown that by setting the incident beam angle to ϕ = 4.76° (between optical axis of objective lens and beam axis) and rotating the beam about the optical axis in 17 discrete angular positions, 91% of speckle noise in the structural images can be reduced. Furthermore, a precision of 0.0032 µl/s is achieved for flow rate measurement with the same beam angle, using three discrete angular positions around the optical axis. In-vivo experiments on human skin and chicken embryo were also implemented to further verify the performance of speckle noise reduction and flow rate measurement of MHB-SDOCT.
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8
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Wartak A, Beer F, Desissaire S, Baumann B, Pircher M, Hitzenberger CK. Investigating spontaneous retinal venous pulsation using Doppler optical coherence tomography. Sci Rep 2019; 9:4237. [PMID: 30862956 PMCID: PMC6414623 DOI: 10.1038/s41598-019-40961-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 02/26/2019] [Indexed: 12/26/2022] Open
Abstract
We demonstrate the advantages of optical coherence tomography (OCT) imaging for investigation of spontaneous retinal venous pulsation (SRVP). The pulsatile changes in venous vessel caliber are analyzed qualitatively and quantitatively using conventional intensity-based OCT as well as the functional extension Doppler OCT (DOCT). Single-channel and double-channel line scanning protocols of our multi-channel OCT prototype are employed to investigate venous pulsatile caliber oscillations as well as venous flow pulsatility in the eyes of healthy volunteers. A comparison to recordings of scanning laser ophthalmoscopy (SLO) – a standard en-face imaging modality for evaluation of SRVP – is provided, emphasizing the advantages of tomographic image acquisition. To the best of our knowledge, this is the first quantitative time-resolved investigation of SRVP and associated retinal perfusion characteristics using OCT.
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Affiliation(s)
- Andreas Wartak
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, 1090, Austria.
| | - Florian Beer
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, 1090, Austria
| | - Sylvia Desissaire
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, 1090, Austria
| | - Bernhard Baumann
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, 1090, Austria
| | - Michael Pircher
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, 1090, Austria
| | - Christoph K Hitzenberger
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, 1090, Austria
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9
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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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10
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Ginner L, Wartak A, Salas M, Augustin M, Niederleithner M, Wurster LM, Leitgeb RA. Synthetic subaperture-based angle-independent Doppler flow measurements using single-beam line field optical coherence tomography in vivo. OPTICS LETTERS 2019; 44:967-970. [PMID: 30768032 DOI: 10.1364/ol.44.000967] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We demonstrate a synthetic subaperture-based angle-independent Doppler flow calculation, using a line field spectral domain optical coherence tomography system. The high speed of the system features a high phase stability over the volume, which is necessary to apply synthetic subapertures in the aperture plane. Thus, the flow component for each subaperture can be reconstructed in postprocessing. Capillary phantom and in vivo retinal imaging experiments were performed to validate and demonstrate angle-independent Doppler flow calculation.
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11
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Scholler J, Mazlin V, Thouvenin O, Groux K, Xiao P, Sahel JA, Fink M, Boccara C, Grieve K. Probing dynamic processes in the eye at multiple spatial and temporal scales with multimodal full field OCT. BIOMEDICAL OPTICS EXPRESS 2019; 10:731-746. [PMID: 30800511 PMCID: PMC6377896 DOI: 10.1364/boe.10.000731] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 01/07/2019] [Accepted: 01/07/2019] [Indexed: 05/08/2023]
Abstract
We describe recent technological progress in multimodal en face full-field optical coherence tomography that has allowed detection of slow and fast dynamic processes in the eye. We show that by combining static, dynamic and fluorescence contrasts we can achieve label-free high-resolution imaging of the retina and anterior eye with temporal resolution from milliseconds to several hours, allowing us to probe biological activity at subcellular scales inside 3D bulk tissue. Our setups combine high lateral resolution over a large field of view with acquisition at several hundreds of frames per second which make it a promising tool for clinical applications and biomedical studies. Its contactless and non-destructive nature is shown to be effective for both following in vitro sample evolution over long periods of time and for imaging of the human eye in vivo.
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Affiliation(s)
- Jules Scholler
- Institut Langevin, ESPCI Paris, CNRS, PSL University, 1 rue Jussieu, 75005 Paris,
France
| | - Viacheslav Mazlin
- Institut Langevin, ESPCI Paris, CNRS, PSL University, 1 rue Jussieu, 75005 Paris,
France
| | - Olivier Thouvenin
- Institut Langevin, ESPCI Paris, CNRS, PSL University, 1 rue Jussieu, 75005 Paris,
France
| | - Kassandra Groux
- Institut Langevin, ESPCI Paris, CNRS, PSL University, 1 rue Jussieu, 75005 Paris,
France
- LLTech SAS, 29 Rue du Faubourg Saint Jacques, Paris, 75014,
France
| | - Peng Xiao
- Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou,
China
| | - José-Alain Sahel
- Vision Institute/CIC 1423, UPMC-Sorbonne Universities, UMR_S 968/INSERM, U968/CNRS, UMR_7210, 17 Rue Moreau, Paris, 75012,
France
- Quinze-Vingts National Eye Hospital, 28 Rue de Charenton, Paris, 75012,
France
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213,
USA
| | - Mathias Fink
- Institut Langevin, ESPCI Paris, CNRS, PSL University, 1 rue Jussieu, 75005 Paris,
France
| | - Claude Boccara
- Institut Langevin, ESPCI Paris, CNRS, PSL University, 1 rue Jussieu, 75005 Paris,
France
- LLTech SAS, 29 Rue du Faubourg Saint Jacques, Paris, 75014,
France
| | - Kate Grieve
- Vision Institute/CIC 1423, UPMC-Sorbonne Universities, UMR_S 968/INSERM, U968/CNRS, UMR_7210, 17 Rue Moreau, Paris, 75012,
France
- Quinze-Vingts National Eye Hospital, 28 Rue de Charenton, Paris, 75012,
France
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12
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Design Considerations for Murine Retinal Imaging Using Scattering Angle Resolved Optical Coherence Tomography. APPLIED SCIENCES-BASEL 2018. [DOI: 10.3390/app8112159] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Optical coherence tomography (OCT), an optical imaging approach enabling cross-sectional analysis of turbid samples, is routinely used for retinal imaging in human and animal models of diseases affecting the retina. Scattering angle resolved (SAR-)OCT has previously been demonstrated as offering additional contrast in human studies, but no SAR-OCT system has been reported in detail for imaging the retinas of mice. An optical model of a mouse eye was designed and extended for validity at wavelengths of light around 1310 nm; this model was then utilized to develop a SAR-OCT design for murine retinal imaging. A Monte Carlo technique simulates light scattering from the retina, and the simulation results are confirmed with SAR-OCT images. Various images from the SAR-OCT system are presented and utility of the system is described. SAR-OCT is demonstrated as a viable and robust imaging platform to extend utility of retinal OCT imaging by incorporating scattering data into investigative ophthalmologic analysis.
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13
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Wartak A, Beer F, Baumann B, Pircher M, Hitzenberger CK. Adaptable switching schemes for time-encoded multichannel optical coherence tomography. JOURNAL OF BIOMEDICAL OPTICS 2018; 23:1-12. [PMID: 29797866 DOI: 10.1117/1.jbo.23.5.056010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 04/30/2018] [Indexed: 05/16/2023]
Abstract
We introduce the approach of variable time encoding for multichannel optical coherence tomography (OCT). High-speed fiber optical switches are applied for sequential sample arm switching to enable quasisimultaneous image acquisition from three different orientation angles. In comparison with previous multichannel OCT (using simultaneous sample illumination), time-encoded multichannel OCT has no need for division of illumination power among the respective channels to satisfy laser safety requirements. Especially for ophthalmic applications-in particular retinal imaging, which the presented prototype was developed for-this advantage strongly influences image quality through an enhanced sensitivity. Nevertheless, time encoding comes at the cost of a decrease in imaging speed due to sequential channel illumination. For the typical multichannel OCT modality Doppler OCT, this results in a reduction of the maximum unambiguously determinable Doppler velocity. However, we demonstrate that this drawback can be overcome by adaptation of the illumination channel switching scheme. Thus, a re-extension of the maximum unambiguously determinable Doppler frequency to the full A-scan rate of the tunable light source is presented. The performance of the technique is demonstrated by flow phantom experiments and measurements of retinal blood flow in the eyes of healthy human volunteers.
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Affiliation(s)
- Andreas Wartak
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Florian Beer
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
- Vienna University of Technology, Institute of Applied Physics, Vienna, Austria
| | - Bernhard Baumann
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Michael Pircher
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - Christoph K Hitzenberger
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
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14
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Wartak A, Augustin M, Haindl R, Beer F, Salas M, Laslandes M, Baumann B, Pircher M, Hitzenberger CK. Multi-directional optical coherence tomography for retinal imaging. BIOMEDICAL OPTICS EXPRESS 2017; 8:5560-5578. [PMID: 29296488 PMCID: PMC5745103 DOI: 10.1364/boe.8.005560] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 11/04/2017] [Accepted: 11/09/2017] [Indexed: 05/22/2023]
Abstract
We introduce multi-directional optical coherence tomography (OCT), a technique for investigation of the scattering properties of directionally reflective tissue samples. By combining the concepts of multi-channel and directional OCT, this approach enables simultaneous acquisition of multiple reflectivity depth-scans probing a mutual sample location from differing angular orientations. The application of multi-directional OCT in retinal imaging allows for in-depth investigations on the directional reflectivity of the retinal nerve fiber layer, Henle's fiber layer and the photoreceptor layer. Major ophthalmic diseases (such as glaucoma or age-related macular degeneration) have been reported to alter the directional reflectivity properties of these retinal layers. Hence, the concept of multi-directional OCT might help to gain improved understanding of pathology development and progression. As a first step, we demonstrate the capabilities of multi-directional OCT in the eyes of healthy human volunteers.
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Affiliation(s)
- Andreas Wartak
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20 / 4L, 1090 Vienna, Austria
| | - Marco Augustin
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20 / 4L, 1090 Vienna, Austria
| | - Richard Haindl
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20 / 4L, 1090 Vienna, Austria
| | - Florian Beer
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20 / 4L, 1090 Vienna, Austria
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstraße 8-10/134, 1040 Vienna, Austria
| | - Matthias Salas
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20 / 4L, 1090 Vienna, Austria
| | - Marie Laslandes
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20 / 4L, 1090 Vienna, Austria
| | - Bernhard Baumann
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20 / 4L, 1090 Vienna, Austria
| | - Michael Pircher
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20 / 4L, 1090 Vienna, Austria
| | - Christoph K. Hitzenberger
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20 / 4L, 1090 Vienna, Austria
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Hitzenberger CK. Adolf Friedrich Fercher: a pioneer of biomedical optics. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:1-8. [PMID: 29148272 DOI: 10.1117/1.jbo.22.12.121704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 10/26/2017] [Indexed: 06/07/2023]
Abstract
Adolf Friedrich Fercher, an outstanding pioneer of biomedical optics, passed away earlier this year. He was a brilliant and visionary researcher who pioneered various fields of biomedical optics, such as laser speckle flowgraphy, tissue interferometry, and optical coherence tomography (OCT). On the occasion of the 25th anniversary of OCT, this paper reviews and commemorates Fercher's pioneering work.
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Affiliation(s)
- Christoph K Hitzenberger
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
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16
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Ocular fundus pulsations within the posterior rat eye: Chorioscleral motion and response to elevated intraocular pressure. Sci Rep 2017; 7:8780. [PMID: 28821834 PMCID: PMC5562765 DOI: 10.1038/s41598-017-09310-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 07/25/2017] [Indexed: 12/13/2022] Open
Abstract
A multi-functional optical coherence tomography (OCT) approach is presented to determine ocular fundus pulsations as an axial displacement between the retina and the chorioscleral complex in the albino rat eye. By combining optical coherence elastography and OCT angiography (OCTA), we measure subtle deformations in the nanometer range within the eye and simultaneously map retinal and choroidal perfusion. The conventional OCT reflectivity contrast serves as a backbone to segment the retina and to define several slabs which are subsequently used for quantitative ocular pulsation measurements as well as for a qualitative exploration of the multi-functional OCT image data. The proposed concept is applied in healthy albino rats as well as in rats under acute elevation of the intraocular pressure (IOP). The evaluation of this experiment revealed an increased pulsatility and deformation between the retinal and chorioscleral complex while increasing the IOP level from 15 mmHg to 65 mmHg. At IOP levels exceeding 65 mmHg, the pulsatility decreased significantly and retinal as well as choroidal perfusion vanished in OCTA. Furthermore, the evaluation of the multi-parametric experiment revealed a spatial correlation between fundus pulsatility and choroidal blood flow. This indicates that the assessed pulsatility may be a valuable parameter describing the choroidal perfusion.
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Klein T, Huber R. High-speed OCT light sources and systems [Invited]. BIOMEDICAL OPTICS EXPRESS 2017; 8:828-859. [PMID: 28270988 PMCID: PMC5330584 DOI: 10.1364/boe.8.000828] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 01/02/2017] [Accepted: 01/03/2017] [Indexed: 05/18/2023]
Abstract
Imaging speed is one of the most important parameters that define the performance of optical coherence tomography (OCT) systems. During the last two decades, OCT speed has increased by over three orders of magnitude. New developments in wavelength-swept lasers have repeatedly been crucial for this development. In this review, we discuss the historical evolution and current state of the art of high-speed OCT systems, with focus on wavelength swept light sources and swept source OCT systems.
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Affiliation(s)
- Thomas Klein
- Optores GmbH, Gollierstr. 70, 80339 Munich, Germany
| | - Robert Huber
- Institut für Biomedizinische Optik, Universität zu Lübeck, Peter-Monnik-Weg 4, 23562 Lübeck, Germany
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