Detection of Stroke, Blood Vessel Landmarks, and Leptomeningeal Anastomoses in Mouse Brain Imaging

Abstract

Collateral connections in the brain, also known as Leptomeningeal Anastomoses, are connections between blood vessels originating from different arteries. Despite limited knowledge, they are suggested as an important contributor to cerebral stroke recovery that allows additional blood flow through the affected area. However, few databases and algorithms exist for this specific task of locating them. In this paper, a MATLAB program is developed to find these connections and detect strokes to replace manual labeling by professionals. The limited data available for this study are 23 2D microscopy images of mice cerebral vascular structures highlighted by dyes. In the images, strokes are shown to diminish the pixel count of vessels below 80\% compared to the healthy brain. Stroke classification error is greatly reduced by narrowing the scope from comparing the entire hemisphere to one smaller region. A novel way of finding collateral connections is utilizing connected components. Connected components organize all adjacent pixels into a group. All collateral connections can be found on the border of two neighboring arterial flow regions, and belong to the same group of connected components with the arterial source from each side. Along with finding collateral connections, a newly created coordinate system allows regions to be defined relative to the brain landmarks, based on the brain's center, orientation, and scale. The method newly proposed in this paper combines stroke detection, brain coordinate system extraction, and collateral connection detection in stroke-affected mouse brains using only image processing techniques. This allows a simpler, more explainable result on limited data than other techniques such as supervised machine learning. In addition, the new method does not require ground truth and high image count for training. This automated process was successfully interpreted by medical experts, which allows for further research into automating collateral connection detection in 3D.