Abstract T MP55: Utility of 4D-MRA to Measure Blood Flow Velocity in Cerebral Major Arteries

Abstract

Transcranial Doppler is widely used clinically to measure blood flow velocity (BFV) in cerebral major arteries. This method, however, has a limitation in that its successful measurement depends on the accessibility of patients’ cranial window and the technical ability of operators. We therefore developed a novel method to measure BFV in cerebral major arteries with 4D-MRA, which was less susceptible to patients and the conditions of the operators. Methods: 4D-MRA was performed with a 3T MR unit (Achieva TX; Philips Medical Systems) using arterial spin labeling methods. The blood flow through the internal carotid arteries (ICA) and the basilar artery (BA) within imaging range was visualized by using look-locker readout methods. BFV was calculated by dividing the flow distance traveled in the arteries by the time elapsed. BFV of 34 patients (non-vascular disease:11, ICA stenotic disease:6, moyamoya disease:9, and cerebral aneurysm:8) were measured using the 4D-MRA method and the 2D phase contrast method. Results: In the case of patients with non-vascular diseases, mean BFV of the right ICA, the left ICA, and the BA was 24.5±7.0, 23.3±6.9, and 17.2±5.1 cm/sec, respectively. Correlation between BFV values from the 4D-MRA method and those from the 2D phase contrast method was statistically significant (r=0.78, p<0.01). In the case of patients with ICA severe stenosis (more than 90%), BFV of the stenotic ICA was decreased to 9~11cm/sec (40~50% of BFV of the contralateral ICA). In the case of patients with advanced-stage moyamoya disease, BFV of the ICA was decreased to 9~16cm/sec (30~50% of BFV of the BA). The BFV decreases were related to CBF reduction in some cases if the development of the collateral circulation was insufficient. In the patients with aneurysm, BFV of the artery proximal to aneurysm tended to be increased except for the decrease in cavernous ICA giant aneurysm. Conclusions: We could steadily obtain BFV in all patients by using the 4D-MRA method without any operational difficulties. In this preliminary study, we observed BFV decrease in ICA stenotic disease and moyamoya disease, and BFV increase in cerebral aneurysm. This novel 4D-MRA method to measure BFV may become a promising tool for pathophysiological evaluation of cerebrovascular diseases.