Scanning protocols dedicated to smart velocity ranging in Spectral OCT

Grulkowski, Ireneusz; Gorczyńska, Iwona; Szkulmowski, Maciej; Szlag, Daniel; Szkulmowska, Anna; Leitgeb, Rainer A.; Kowalczyk, Andrzej; Wojtkowski, Maciej

doi:10.1364/oe.17.023736

Cited by 98 publications

(90 citation statements)

References 38 publications

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“…The color-coded angiogram can be superimposed on a gray-scale, cross-sectional, structural OCT image to demonstrate blood flow and structural information simultaneously. Flow projection artifacts are a common problem for existing OCT angiography techniques (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). To better distinguish and interpret the blood flow within different layers, a negative filter was used to mask projection artifacts from the larger caliber retinal vessels (24).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

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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Section: Discussionmentioning

confidence: 99%

“…Initially, Doppler OCT angiography methods were investigated for the visualization and measurement of blood flow (3)(4)(5)(6)(7)(8). Because Doppler OCT is only sensitive to motion parallel to the OCT probe beam, it is limited in its ability to image retinal and choroidal circulations, which are predominantly perpendicular to the OCT beam.…”

mentioning

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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“…SD-OCT in the 800 nm region currently outperforms SS-OCT in terms of resolution due to the availability of broadband lasers. Also SD-OCT now achieves ultra high-speed, comparable to the fastest available SS-OCT systems due to advances in camera technology [16][17][18]. However, SD-OCT requires a significant amount of signal processing for background handling and resampling.…”

Section: Biophotonicsmentioning

confidence: 99%

Artefact reduction for cell migration visualization using spectral domain optical coherence tomography

Höfer¹,

Povazˇay²,

Hermann³

et al. 2011

Journal of Biophotonics

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Visualization of cell migration during chemotaxis using spectral domain optical coherence tomography (OCT) requires non‐standard processing techniques. Stripe artefacts and camera noise floor present in OCT data prevent detailed computer‐assisted reconstruction and quantification of cell locomotion. Furthermore, imaging artefacts lead to unreliable results in automated texture based cell analysis. Here we characterize three pronounced artefacts that become visible when imaging sample structures with high dynamic range, e.g. cultured cells: (i) time‐varying fixed‐pattern noise; (ii) stripe artefacts generated by background estimation using tomogram averaging; (iii) image modulations due to spectral shaping. We evaluate techniques to minimize the above mentioned artefacts using an 800 nm optical coherence microscope. Effect of artefact reduction is shown exemplarily on two cell cultures, i.e. Dictyostelium on nitrocellulose substrate, and retinal ganglion cells (RGC‐5) cultured on a glass coverslip. Retinal imaging also profits from the proposed processing techniques. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…For the commonly used spectrometer-based OCT systems, PR-DOCT is still limited by a minimum and ambiguous maximum flow velocity, by interference fringe blurring, due to fast axially moving samples and by a nonlinear relation between the Doppler phase shift and the axial sample velocity for the case of an obliquely moving sample. To increase the dynamic velocity range with high flexibility, Grulkowski et al have presented adaptive scanning protocols for DOCT, while preserving a high imaging speed [15]. In this work, the Doppler frequency shift related to the phase shift [16] is calculated between consecutive B-scans or segments, instead of subsequent A-scans as has conventionally been employed, resulting in the benefit of mapping low and high flow.…”

Section: Introductionmentioning

confidence: 99%

Flow Measurement by Lateral Resonant Doppler Optical Coherence Tomography in the Spectral Domain

Walther

Koch

2017

Applied Sciences

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Abstract:In spectral domain optical coherence tomography (SD-OCT), any transverse motion component of a detected obliquely moving sample results in a nonlinear relationship between the Doppler phase shift and the axial sample velocity restricting phase-resolved Doppler OCT (PR-DOCT). The size of the deviation from the linear relation depends on the amount of the transverse velocity component, given by the Doppler angle, and the height of the absolute sample velocity. Especially for very small Doppler angles between the horizontal and flow direction, and high flow velocities, the detected Doppler phase shift approaches a limiting value, making an unambiguous measurement of the axial sample velocity by PR-DOCT impossible. To circumvent this limitation, we propose a new method for resonant Doppler flow quantification in spectral domain OCT, where the scanner movement velocity is matched with the transverse velocity component of the sample motion similar to a tracking shot, where the camera is moved with respect to the sample. Consequently, the influence of the transverse velocity component of the tracked moving particles on the Doppler phase shift is negligible and the linear relation between the phase shift and the axial velocity component can be considered for flow velocity calculations. The proposed method is verified using flow phantoms on the basis of 1% Intralipid solution and diluted human blood.

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Scanning protocols dedicated to smart velocity ranging in Spectral OCT

Cited by 98 publications

References 38 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

Artefact reduction for cell migration visualization using spectral domain optical coherence tomography

Flow Measurement by Lateral Resonant Doppler Optical Coherence Tomography in the Spectral Domain

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