Abstract
Angiogenesis is recognized as a crucial component of many neurovascular diseases such as stroke, carcinogenesis, and neurotoxicity of abused drug. The ability to track angiogenesis will facilitate a better understanding of disease progression and assessment of therapeutical effects. Optical coherence angiography (OCTA) is a promising tool to assess 3D microvascular networks due to its micron-level resolution, high sensitivity, and relatively large field of view. However, quantitative OCTA image analysis for characterization of microvascular network changes, including accurately tracking the progression of angiogenesis, remains a challenge. In this paper, we proposed an angiogenesis tracking algorithm which combines improved vessel segmentation and brain boundary detection methods to significantly enhance time-lapse OCTA images for quantification of microvascular network changes. Specifically, top-hat enhancement and optimally oriented flux (OOF) algorithms facilitated accurate segmentation of cerebrovascular networks (including capillaries); graph-search based brain boundary detection enabled coregistration of 3D OCTA data sets from different time points for accurate vessel density assessment and analysis of their changes in various cortical layers. Results show that this algorithm significantly enhanced the accuracy of vessel segmentation compared to Hessian method. Application to chronic cocaine intoxication study shows effectively reduced errors in chronic tracking of microvasculature and more accurate assessment of vessel density changes induced by angiogenesis.
Highlights
Optical Coherence Angiography (OCTA) is a non-invasive and label-free method to obtain high contrast 3D image of blood vessel network in vivo utilizing the dynamic OCT speckle signal induced by moving red blood cells [1]
In addition to avoiding inclusion of nearby objects, optimally oriented flux (OOF) can retain the sharpness of vessel edges because it does not rely on Gaussian kernel with different scales for multiscale detection
3 green arrows point to 3 capillary fragments adjacent to large branch vessels missed by Hessian method but segmented by OOF (Fig. 5(d’)), showing that OOF can effectively reduce false negative rate
Summary
Optical Coherence Angiography (OCTA) is a non-invasive and label-free method to obtain high contrast 3D image of blood vessel network in vivo utilizing the dynamic OCT speckle signal induced by moving red blood cells [1]. J. Vakoc, etc, applied optical frequency domain imaging to monitor tumor vascular change in response to antiangiogenesis therapy [2]. Zhongdi Chu etc detected and assessed retinal vascular abnormalities with multiple quantitative indexes obtained from OCTA [4]. Different image acquisition and processing methods have been introduced in these studies tools to identify changes in the microvascular network caused by neurovascular diseases; more accurate quantitative assessment of OCTA images is needed to better understand angiogenesisassociated disease mechanisms and to develop more efficient therapeutic strategies
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