Swept-Source OCT Angiography of the Retinal Vasculature Using Intensity Differentiation-based Optical Microangiography Algorithms

Abstract

Background and Objective To demonstrate the feasibility of using a 1050 nm swept-source OCT (SS-OCT) system to achieve noninvasive retinal vasculature imaging in human eyes. Materials and Methods Volumetric datasets were acquired using a ZEISS 1 µm SS-OCT prototype that operated at an A-line rate of 100 kHz. A scanning protocol designed to allow for motion contrast processing, referred to as OCT angiography or optical microangiography (OMAG), was used to scan ~3 mm × 3 mm area in the central macular region of the retina within ~4.5 seconds. Intensity differentiation based OMAG algorithm was used to extract 3-D retinal functional microvasculature information. Results Intensity signal differentiation generated capillary-level resolution en face OMAG images of the retina. The parafoveal capillaries were clearly visible, thereby allowing visualization of the foveal avascular zone (FAZ) in normal subjects. Conclusion The capability of OMAG to produce retinal vascular images was demonstrated using the ZEISS 1 µm SS-OCT prototype. This technique can potentially have clinical value for studying retinal vasculature abnormalities.

Comparative Analysis of Automatic Layer-by-Layer Segmentation Using Optical Coherent Tomographs Dri Oct and Retinascan-3000 in Healthy Patients

“…Учитывая разный принцип работы TD-OCT, SD-OCT и SS-OCT, а также разные возможности оптиче-ских когерентных томографов DRI OCT TRITON и OCT RETINASCAN-3000, послойное сегментирование сет-чатки в автоматическом режиме является неодинаковым [1,10,11,12]. Отсутствие возможности послойного сег-ментирования в системе TD-OCT послужило основани-ем для исключения ее участия в данном сравнительном качественном анализе.…”

Wide-field imaging of retinal vasculature using optical coherence tomography-based microangiography provided by motion tracking

“…6,7,34,37 The algorithm is based on an OCT-complex signal differentiation approach that was recently published. 6,7 In brief, the OCT signals between adjacent B-scans are directly differentiated among the 4-repeated B-scans, and then averaged to achieve one crosssectional blood flow image.…”

“…To achieve OMAG imaging of retinal vasculatures, a repeated B-mode scan protocol was adopted to acquire volumetric datasets, i.e., a number of repeated B-scans were acquired at each spatial step over the slow axis direction (y-axis). 34 For each B-scan, the number of A-scans was 240, covering a lateral distance of ∼2.4 mm. The direction of the B-scan is called the fast scan direction (x).…”

“…In each step, B-scans were repeated four times in the current study for extracting the flow signal because this number has been tested to provide a reasonable imaging performance for OMAG in terms of acceptable imaging time and image quality. 10,34 The time difference between two successive B-scans was ∼4.5 ms, roughly corresponding to a frame rate of 224 fps. Based on this scan protocol and system speed, the total time for a single volume acquisition was about 3.6 s, not including the adjustment time before the data collection.…”

Advances in Optical Coherence Tomography Angiography

“…[1][2][3] The software compares the decorrelation signal or phase variance between consecutive OCT B-scans acquired at the same retinal cross-section to detect motion contrast. [4][5][6] Multiple OCTA image artifacts may affect image quality. Motion artifact due to blinking or gross eye movement appear as horizontal or vertical black and white lines, respectively, and motion correction software can create vessel doubling, stretching of the image, quilting, or loss of detail in the attempt to compensate for these motion artifacts.…”