Optical coherence tomography angiography for mapping cerebral microvasculature based on normalized differentiation analysis

Abstract

Optical coherence tomography angiography (OCTA) is a label-free, noninvasive biomedical imaging modality for mapping microvascular networks and quantifying blood flow velocities in vivo. Simple computation and fast processing are critical for the OCTA in some applications. Herein, we report on a normalized differentiation method for mapping cerebral microvasculature with the advantages of simple analysis and high image quality, benefitting from computation of differentiation and characteristics of normalization. Normalized differentiation values are validated to have a nearly linear relationship with flow velocities in a range using a flow phantom. The measurements in a rat cerebral cortex show that the OCTA based on the normalized differentiation analysis can generate microvascular images with high quality and monitor spatiotemporal dynamics of blood flow with simple computation and fast processing before and after localized ischemia induced by arterial occlusion.

Imaging peritoneal blood vessels through optical coherence tomography angiography for laparoscopic surgery

“…In this section, we present a comparative analysis of different OCTA algorithms for in vivo imaging of pig blood vessels hidden inside the peritoneum. Specifically, we compared the performance of four OCTA algorithms: normalized differentiation analysis [30], Pearson cross‐correlation [20], normalized second order correlation, and normalized second order correlation with background noise compensation [23]. Normalized intensity differentiation utilizes the sum of two intensity terms as the normalization factor to increase the SNR of OCTA results in moving scatterers.…”

“…The split-spectrum amplitude-decorrelation angiography method utilizes separate narrow band spectra to reduce sensitivity against pulsatile bulk [27]. The intensity differentiation-based OCTA method visualizes the microvasculature from simple intensity subtraction over repeated B-frames [28,29], and inter-A-lines [30].…”

Simplifying intensity variance analysis for optical coherence tomography-based angiography

“…[4] Various analysis methods, such as the phase-resolved methods, the differential methods, and the intensity variance methods, have been developed for the OCTA analysis. [5,6] The intensity variance methods can map the microvascular network while quantifying the blood flow rate. However, the statistical calculations of intensity variances require high computational costs.…”