Statistical analysis of motion contrast in optical coherence tomography angiography

Abstract

Optical coherence tomography angiography (Angio-OCT), mainly based on the temporal dynamics of OCT scattering signals, has found a range of potential applications in clinical and scientific research. Based on the model of random phasor sums, temporal statistics of the complex-valued OCT signals are mathematically described. Statistical distributions of the amplitude differential and complex differential Angio-OCT signals are derived. The theories are validated through the flow phantom and live animal experiments. Using the model developed, the origin of the motion contrast in Angio-OCT is mathematically explained, and the implications in the improvement of motion contrast are further discussed, including threshold determination and its residual classification error, averaging method, and scanning protocol. The proposed mathematical model of Angio-OCT signals can aid in the optimal design of the system and associated algorithms.

Optical coherence tomography angiography offers comprehensive evaluation of skin optical clearingin vivoby quantifying optical properties and blood flow imaging simultaneously

“…By mathematically analyzing the temporal dynamics of light scattering, Angio-OCT is capable of contrasting the dynamic blood flow against the static tissue bed, [27][28][29][30][31][32] and enables a label-free, motion-contrast 3-D microangiography. Thus, Angio-OCT is quite suitable for OCA characterization by measuring skin optical properties and evaluating blood flow imaging simultaneously.…”

OCT Angiography (OCTA) in Retinal Diagnostics

“…These statistical parameters, potentially after additional post-processing and contrast enhancement, are subsequently taken as the resulting OCTA signal in arbitrary units. As an alternative to these statistical parameter based OCTA signal construction methods, underlying probabilistic statistical models for the random OCT signal from sample locations with and without directed flow can be derived from theory and experiment [9][10][11]. Based on these underlying models and the repeated OCT signal observations, a probability for being static (versus in flow) can be assigned to each measured location.…”

OCT Angiography: A Technique for the Assessment of Retinal and Optic Nerve Diseases in the Pediatric Population

“…OCT-A obtains images of the retinal vessels by comparing the signals of a series of consecutive B-scans performed at the same location [5]. The temporal evolution of the optical coherence tomography (OCT) signal, caused by the motion of scattering particles such as erythrocytes within vessels, allows the visualization of functional blood vessels [2,[5][6][7].…”

“…OCT-A obtains images of the retinal vessels by comparing the signals of a series of consecutive B-scans performed at the same location [5]. The temporal evolution of the optical coherence tomography (OCT) signal, caused by the motion of scattering particles such as erythrocytes within vessels, allows the visualization of functional blood vessels [2,[5][6][7]. Furthermore, OCT-A allows a separate visualization of different capillary networks (inner retina, outer retina, and choriocapillaris) [4], which are allocated to the superficial or deep retinal slabs depending on the segmentation method and retinal layer designation used by each device [2].…”