Doppler velocity detection limitations in spectrometer-based versus swept-source optical coherence tomography

Hendargo, Hansford C.; McNabb, Ryan P.; Dhalla, Al-Hafeez; Shepherd, Neal; Izatt, Joseph A.

doi:10.1364/boe.2.002175

Cited by 123 publications

(124 citation statements)

References 45 publications

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“…1F). This en face choroidal image is achieved by taking advantage of the OCT signal void produced by interference fringe washout in regions of very high flow velocity (16).…”

Section: Resultsmentioning

confidence: 99%

Quantitative optical coherence tomography angiography of vascular abnormalities in the living human eye

Jia

Bailey

Hwang

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

600

469

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Retinal vascular diseases are important causes of vision loss. A detailed evaluation of the vascular abnormalities facilitates diagnosis and treatment in these diseases. Optical coherence tomography (OCT) angiography using the highly efficient split-spectrum amplitude decorrelation angiography algorithm offers an alternative to conventional dye-based retinal angiography. OCT angiography has several advantages, including 3D visualization of retinal and choroidal circulations (including the choriocapillaris) and avoidance of dye injection-related complications. Results from six illustrative cases are reported. In diabetic retinopathy, OCT angiography can detect neovascularization and quantify ischemia. In age-related macular degeneration, choroidal neovascularization can be observed without the obscuration of details caused by dye leakage in conventional angiography. Choriocapillaris dysfunction can be detected in the nonneovascular form of the disease, furthering our understanding of pathogenesis. In choroideremia, OCT's ability to show choroidal and retinal vascular dysfunction separately may be valuable in predicting progression and assessing treatment response. OCT angiography shows promise as a noninvasive alternative to dye-based angiography for highly detailed, in vivo, 3D, quantitative evaluation of retinal vascular abnormalities.optical coherence tomography angiography | ophthalmic imaging | ocular circulation O ptical coherence tomography (OCT) has become the most commonly used imaging modality in ophthalmology. It provides cross-sectional and 3D imaging of the retina and optic nerve head with micrometer-scale depth resolution. Structural OCT enhances the clinician's ability to detect and monitor fluid exudation associated with retinal vascular diseases. Whereas anatomical alterations that impact vision are readily visible, structural OCT has a limited ability to image the retinal or choroidal vasculatures. Furthermore, it is unable to directly detect capillary dropout or pathologic new vessel growth (neovascularization) that are the major vascular changes associated with two of the leading causes of blindness, age-related macular degeneration (AMD) and diabetic retinopathy (1). To visualize these changes, traditional i.v. contrast dye-based angiography techniques are currently used.Fluorescein dye is primarily used to visualize the retinal vasculature. A separate dye, indocyanine green (ICG), is necessary to evaluate the choroidal vasculature. Both fluorescein angiography (FA) and ICG angiography require i.v. injection, which is time consuming, and which can cause nausea, vomiting, and, rarely, anaphylaxis (2). Dye leakage or staining provides information regarding vascular incompetence (e.g., from abnormal capillary growth), but it also obscures the image and blurs the boundaries of neovascularization. Additionally, conventional angiography is 2D, which makes it difficult to distinguish vascular abnormalities within different layers. Therefore, it is desirable to develop a no-injection, dye-free method...

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“…1F). This en face choroidal image is achieved by taking advantage of the OCT signal void produced by interference fringe washout in regions of very high flow velocity (16).…”

Section: Resultsmentioning

confidence: 99%

Quantitative optical coherence tomography angiography of vascular abnormalities in the living human eye

Jia

Bailey

Hwang

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

600

469

View full text Add to dashboard Cite

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“…We suspect that fast flow rates of these vessels induce fringe washout of spectrometerbased OCT signals and cause the signal to drop below the noise level of the system. In that case, the loss of OCT intensity signal within these blood vessels also creates a lack of phase-shift information and pvOCT signal (18). To address this issue, we have applied a similar methodology to the visualization of choroidal vessels by an inversed minimum projection view of the phasevariance processed data segmented over Haller's layer (Fig.…”

Section: Discussionmentioning

confidence: 99%

Optical imaging of the chorioretinal vasculature in the living human eye

Kim

Fingler

Zawadzki

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

188

120

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Detailed visualization of microvascular changes in the human retina is clinically limited by the capabilities of angiography imaging, a 2D fundus photograph that requires an intravenous injection of fluorescent dye. Whereas current angiography methods enable visualization of some retinal capillary detail, they do not adequately reveal the choriocapillaris or other microvascular features beneath the retina. We have developed a noninvasive microvascular imaging technique called phase-variance optical coherence tomography (pvOCT), which identifies vasculature three dimensionally through analysis of data acquired with OCT systems. The pvOCT imaging method is not only capable of generating capillary perfusion maps for the retina, but it can also use the 3D capabilities to segment the data in depth to isolate vasculature in different layers of the retina and choroid. This paper demonstrates some of the capabilities of pvOCT imaging of the anterior layers of choroidal vasculature of a healthy normal eye as well as of eyes with geographic atrophy (GA) secondary to age-related macular degeneration. The pvOCT data presented permit digital segmentation to produce 2D depth-resolved images of the retinal vasculature, the choriocapillaris, and the vessels in Sattler's and Haller's layers. Comparisons are presented between en face projections of pvOCT data within the superficial choroid and clinical angiography images for regions of GA. Abnormalities and vascular dropout observed within the choriocapillaris for pvOCT are compared with regional GA progression. The capability of pvOCT imaging of the microvasculature of the choriocapillaris and the anterior choroidal vasculature has the potential to become a unique tool to evaluate therapies and understand the underlying mechanisms of age-related macular degeneration progression. ocular circulation | ocular vasculature | optical angiography | ophthalmic imaging | Fourier-domain optical coherence tomography

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“…Thus, we could assume that only the externally applied phase shift was effective when we consider the phase difference between two neighboring A-lines. Or the phase shift due to the sample surface variation could be ignored in a similar fashion when calculating the Doppler shift in Doppler OCT [23][24][25]. Figure 2 illustrates the schematic of the off-axis galvano scanner that gives the phase shift to the sample beam while sample scanning, which is necessary to construct a complex spectral interferogram.…”

Section: A Schematic and Methods Introductionmentioning

confidence: 99%

Single-step method for fiber-optic probe-based full-range spectral domain optical coherence tomography

et al. 2013

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We propose a single-step method appropriated for a fiber-optic probe-based full-range spectral domain optical coherence tomography (OCT). The fiber-optic probe was scanned over a sample with a magnetically driven actuator. In the reference arm, a phase shift of π∕2 was applied during two neighbor axial scanning, from which the complex spectral interferogram was directly reconstructed. Since the complexconjugate-free OCT image is obtained by doing just one Fourier transform on the complex interferogram, obtaining the full-range image is simple in algorithm and effective in computation time. Some full-range images of biological samples created with the proposed method are presented and the processing time is analyzed.

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Doppler velocity detection limitations in spectrometer-based versus swept-source optical coherence tomography

Cited by 123 publications

References 45 publications

Quantitative optical coherence tomography angiography of vascular abnormalities in the living human eye

Quantitative optical coherence tomography angiography of vascular abnormalities in the living human eye

Optical imaging of the chorioretinal vasculature in the living human eye

Single-step method for fiber-optic probe-based full-range spectral domain optical coherence tomography

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