Geometrical Complexity of Cortical Microvascularization in Moyamoya Disease

Dilatation of the microvascular diameter is recognized in moyamoya disease and referred to as microvascularization. The purpose of this study was to characterize the cortical microvascularization in moyamoya disease using imaging analysis, and to explore the developmental mechanism of the collateral network around the cortical surface.

A total of 20 hemispheric sides of 14 patients with moyamoya disease were included in this study. From the intraoperative images, cortical surface images were extracted, and binary images were subsequently created. Then the ratio of the microvessels of the brain surface (vascular fraction; VF) and the box-counting fractal dimension (Db) values were calculated. The VF and Db values in the moyamoya disease group were then compared with those in atherosclerotic disease and nonischemic disease groups, and assessed in terms of clinical and radiologic factors.

VF was significantly higher in the moyamoya disease group compared with the atherosclerotic disease group, and Db was significantly higher in the moyamoya disease group compared with the atherosclerotic disease and nonischemic disease groups. In the moyamoya disease group, VF showed a moderate correlation with magnetic resonance angiography (MRA) score. Moreover, Db was significantly higher in the pediatric patients, in the presence of ischemic symptoms, and in the presence of ivy sign, and Db showed a moderate correlation with MRA score and cerebral blood flow in moyamoya disease.

In the patients with moyamoya disease, the cortical microvascularization exhibited increased Db and dilatation of the pial arteries. In moyamoya disease, cortical microvascularization is associated with clinical and radiologic factors. This microvascularization might be a compensatory mechanism in the ischemic condition in moyamoya disease.