Three-dimensional time-of-flight MR-angiography (3D-TOF-MRA) at 5.0T showed comparable capacity to 7.0T for visualizing small vessels, but has not yet been compared with arterial spin labeling (ASL)-based four-dimensional MR-angiography (4D-ASL-MRA) at 5.0T. This study aimed to compare the performance of these two MRA techniques at 5.0T in evaluating Moyamoya disease (MMD).

This retrospective study included 20 consecutive MMD patients who underwent 4D-ASL-MRA with six labeling times (100 ms to 1800 ms) and 3D-TOF-MRA at 5.0T Analyses included Suzuki grades, contrast-to-noise ratio (CNR), number of branches in middle cerebral artery (MCA), and image scores of terminal internal carotid arteries (ICA), stenosis around terminal ICA, distal MCA, Moyamoya vessels, and leptomeningeal anastomosis (LMA) collateral vessels.

Twenty patients (10 females, 33 ± 8 years) with 30 cerebral hemispheres were analyzed. Compared to 3D-TOF-MRA, 4D-ASL-MRA with 900 ms to 1800 ms labeling times demonstrated superior visualization scores for terminal ICA, stenosis around terminal ICA, and LMA (4D-ASL-MRA with 900 ms vs 3D-TOF-MRA: 4.00 ± 0.00 vs 3.50 ± 0.68, 3.00 ± 0.00 vs 2.68 ± 0.55, 2.37 ± 1.19 vs 1.40 ± 0.97, respectively, all p < 0.05), and 4D-ASL-MRA at 1800 ms showed higher CNR in the M4 segment (45.84 ± 20.28 vs 27.54 ± 24.46, p < 0.001) but lower in M1 to M3 segments (65.61 ± 36.22 vs 173.58 ± 148.25, 48.89 ± 29.44 vs 122.86 ± 104.23, 44.68 ± 30.05 vs 78.36 ± 72.64, respectively, all p < 0.05) and more visible distal MCA branches (24.83 ± 5.49 vs 15.03 ± 5.99, p < 0.001). The inter-modality agreement on Suzuki grades between 4D-ASL-MRA and digital subtraction angiography (DSA) was excellent (κ= 0.88), outperforming that between 3D-TOF-MRA and DSA (κ= 0.57).

At 5.0T, 4D-ASL-MRA demonstrated superior visualization of terminal ICA, distal MCA, and collateral vessels in MMD, as well as staging MMD more accurately than 3D-TOF-MRA.