Mapping of vertebral artery perfusion territories using arterial spin labeling MRI

Purpose: To demonstrate the use of a noninvasive arterial spin labeling (ASL) MRI technique and evaluate vertebral artery (VA) territories in the brain. Materials and Methods: Vessel-encoded ASL was used to determine the territories of the left and right VAs in five healthy subjects. Territory maps were analyzed quantitatively by comparing the fractional contributions of the left and right VAs in selected regions of interest within the brain. Results: VA territory maps demonstrated a complicated pattern of perfusion to the posterior aspect of the brain. but were consistent with the posterior cerebral and cerebellar artery distributions. Cerebellar perfusion was predominantly ipsilateral (P < 0.01). The total left and right VA contributions were unequal (P < 0.01), and there was relatively little mixing in the vertebrobasilar system. Conclusion: Vessel-encoded ASL can reveal individual VA territories in the brain. In a small sample of healthy volunteers the VAs appeared to contribute unequally. provide predominantly ipsilateral supply to the cerebellum. and undergo minimal mixing in the basilar artery.