Comparison of TOF-MRA and silent scan-MRA in depicting cerebral arteries in patients with Moyamoya disease

Background Silent scan magnetic resonance angiography (silent-MRA) as an arterial spin labeling technique offering sound reduction is insensitive to saturation effect. Time-of-flight (TOF)-MRA has limitations in terms of fine or slow-flow blood vessels due to sensitive saturation effects. Purpose Silent-MRA was compared with TOF-MRA for visualizing cerebral arteries in patients with Moyamoya disease (MMD). Material and Methods Forty-one patients with MMD were scanned with both silent-MRA and TOF-MRA. Silent-MRA was compared with TOF-MRA both quantitatively and qualitatively. Quantitatively, both signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured. Qualitatively, steno-occlusive severity of the main cerebral arteries and grading of Moyamoya vessels (MMVs) were evaluated. The grading for MMVs was classified into one of five categories (1 = absolutely negative; 5 = absolutely positive). Results Both SNR and CNR were significantly higher in TOF-MRA (SNR = 155.2 ± 90.8; CNR = 116.6 ± 72.0) than in silent-MRA (SNR = 45.8 ± 10.1; CNR = 38.6 ± 10.1) ( P < 0.001). No significant difference in steno-occlusive severity of the main cerebral arteries in either right or left cerebral hemispheres was observed between silent-MRA and TOF-MRA. In grading MMVs, the silent-MRA score (mean ± SD = 4.6 ± 0.5) was significantly higher than that of TOF-MRA (3.2 ± 1.6) ( P < 0.001). Conclusion Silent-MRA appears to better visualize MMVs than TOF-MRA and it can equally depict steno-occlusive lesions of the cerebral arteries.