Visualization of two-dimensional transverse blood flow direction using optical coherence tomography angiography

Abstract

. Significance: Evaluation of vessel patency and blood flow direction is important in various medical situations, including diagnosis and monitoring of ischemic diseases, and image-guided vascular surgeries. While optical coherence tomography angiography (OCTA) is the most widely used functional extension of optical coherence tomography that visualizes three-dimensional vasculature, inability to provide information of blood flow direction is one of its limitations. Aim: We demonstrate two-dimensional (2D) transverse blood flow direction imaging in en face OCTA. Approach: A series of triangular beam scans for the fast axis was implemented in the horizontal direction for the first volume scan and in the vertical direction for the following volume scan, and the inter A-line OCTA was performed for the blood flow direction imaging while the stepwise pattern was used for each slow axis scan. The decorrelation differences between the forward and the backward inter A-line OCTA were calculated for the horizontal and the vertical fast axis scans, and the ratio of the horizontal and the vertical decorrelation differences was utilized to show the 2D transverse flow direction information. Results: OCTA flow direction imaging was verified using flow phantoms with various flow orientations and speeds, and we identified the flow speed range relative to the scan speed for reliable flow direction measurement. We demonstrated the visualization of 2D transverse blood flow orientations in mouse brain vascular networks in vivo . Conclusions: The proposed OCTA imaging technique that provides information of 2D transverse flow direction can be utilized in various clinical applications and preclinical studies.

In vivo imaging of renal microvasculature in a murine ischemia–reperfusion injury model using optical coherence tomography angiography

“…The raw data required for generating OCTA images were acquired using a previously reported swept-source OCT system 22 based on a lab-built short-cavity laser with a 220.4-kHz sweep rate (Fig. 1 A).…”

In vivo imaging of renal microvasculature in a murine ischemia-reperfusion injury model using optical coherence tomography angiography

“…The raw data required for generating OCTA images were acquired using a previously reported swept-source OCT system 22 based on a lab-built short-cavity laser with a 220.4-kHz sweep rate (Fig. 1A).…”

Complex Correlated Phase Gradient Variance Based Optical Coherence Tomography Angiography

“…Another approach is split-spectrum amplitude and phase-gradient angiography (SS-APGA) [27], which can eliminate the depth-independent bulk phase shift and minimize the trigger-jitter-induced phase error. Benefiting from the advantages, the two methods have drawn tremendous attention in biomedical research [28], [29], [30], [31], [32], [33], [34]. However, they both provide a relatively low motion contrast.…”