Preliminary application of CT perfusion source images for evaluating regional collateral circulation in unilateral Moyamoya disease

Moyamoya disease (MMD) is characterized by chronic progressive stenosis or occlusion of the terminal portion and main branches of the bilateral internal carotid arteries (ICAs). If the angiographic findings were unilateral, the case would be considered unilateral MMD (1). By the time of diagnosis, these patients have developed collateral vessels to stabilize blood flow. However, these collaterals are imperfect and prone to bleeding, aneurysm, and thrombosis (2). Most adult patients with symptomatic MMD experience a chronic decrease in blood flow. Therefore, it is necessary to establish good collateral circulation to prevent the risks of ischemia and hemorrhage (3). Precise analysis of radiological findings including leptomeningeal collateralization and parenchymal perfusion is essential to make an accurate diagnosis, predict outcomes, and determine appropriate therapeutic strategies and follow-up (4). Digital subtraction angiography (DSA) is a commonly accepted method to evaluate the presence of collateral status (3), as it exhibits high spatial and temporal resolution of inflow dynamics, and has the ability to interrogate specific feeding vessels selectively. However, this is an invasive, time-consuming, and complex procedure. Thus, it would be helpful to have information regarding the collateral status using a noninvasive and easily accessible tomographic approach before and after revascularization therapy