Evaluation of blood flow dynamics using MRA with presaturation method

Magnetic resonance angiography was applied to the study of blood flow dynamics in the extracranial-intracranial arterial bypass and the circle of Willis in 25 patients with cerebrovascular disease and one normal volunteer. In conjunction with three-dimensional gradient-echo acquisitions, selective presaturation of individual vessels was used to determine the direction of blood flow and the origin of the vascular supply. Presaturation causes signal loss within the territory supplied by the presaturated artery, without affecting vessels not crossing the presaturation slab. Magnetic resonance angiography with presaturation to the temporal skin could be used to evaluate patency of the extracranial-intracranial arterial bypass in patients who received bypass surgery. Moreover, with presaturation to the internal carotid artery or the anterior communicating artery or the basilar artery, the collateral blood flow in the circle of Willis in patients with occlusive cerebrovascular disease could be evaluated. The results obtained were correlated with those from conventional angiography. Magnetic resonance angiography with presaturation allows diagnosis of patency of a bypass or blood flow dynamics in the circle of Willis on both, static and kinetic images, and is considered as a useful, noninvasive and reproducible modality. (author)