Review of speckle and phase variance optical coherence tomography to visualize microvascular networks

Abstract

Abstract. High-resolution mapping of microvasculature has been applied to diverse body systems, including the retinal and choroidal vasculature, cardiac vasculature, the central nervous system, and various tumor models. Many imaging techniques have been developed to address specific research questions, and each has its own merits and drawbacks. Understanding, optimization, and proper implementation of these imaging techniques can significantly improve the data obtained along the spectrum of unique research projects to obtain diagnostic clinical information. We describe the recently developed algorithms and applications of two general classes of microvascular imaging techniques: speckle-variance and phase-variance optical coherence tomography (OCT). We compare and contrast their performance with Doppler OCT and optical microangiography. In addition, we highlight ongoing work in the development of variance-based techniques to further refine the characterization of microvascular networks. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Retinal oximetry in humans using visible-light optical coherence tomography [Invited]

“…As a result, it is possible that the effects of speckle might be absorbed into our formula, due to the fact that we used a higher order model. More recently, Mahmud et al reported in a review article on OCT speckle variance that OCT intensity follows Gaussian distribution in solid tissues, while it changes to Rayleigh distribution in fluids [43]. It is worth noting that both these two distributions are the special cases of Rice distribution ( v  leads to Gaussian distribution; and v  leads to Rayleigh distribution).…”

Optical coherence tomography today: speed, contrast, and multimodality

“…136 As mentioned before, it is possible to observe decorrelation or variance of phase, 137,138 speckle, 139,140 or the full complex signal. 141 An important factor, apart from the time interval, is the oversampling ratio, which is the number of A-scans per spot size of the scanning beam.…”

Quantifying the vascular response to ischemia with speckle variance optical coherence tomography

“…The tissue was segmented in each structural (OCT magnitude) image by applying edge-detection to determine the tissue surface and an intensity threshold to exclude noise due to signal fall-off in depth. The segmented tissue mask was first applied to the speckle variance maps, which were then median filtered and de-shadowed using a stepdown exponential filter [54]. Next, bulk motion artifacts were minimized by plotting the average speckle variance for each B-scan in the volume (Fig.…”