Comparative evaluation of 5.0 T and 3.0 T time-of-flight magnetic resonance angiography in assessing collateral circulation in moyamoya angiopathy.

Background: Time-of-flight magnetic resonance angiography (TOF MRA) is a widely recognized noninvasive diagnostic tool of moyamoya angiopathy (MMA). 3.0 T TOF MRA may lack the precision needed to evaluate collaterals in MMA, whereas 5.0 T TOF MRA may enable better visualization of collateral vessels. This study compared the efficacy of 5.0 T and 3.0 T TOF MRA in assessing collateral circulation in patients with MMA.

Methods: A total of 21 patients diagnosed with MMA [male 11; mean age: 35 years (range, 18-57 years)] was included in this study. Qualitative assessments encompassed imaging of the terminal internal carotid arteries (ICAs), distal middle cerebral arteries (MCAs), moyamoya vessels (MMVs), and leptomeningeal anastomosis (LMA) collaterals, using digital subtraction angiography (DSA) as a reference. A semi-quantitative grading system was employed with both 5.0 T and 3.0 T MRI to assess MMV visibility and LMA collaterals, using MMV area scores and leptomeningeal system scores.

Results: The 5.0 T TOF MRA showed better scores for visualization of distal MCAs, MMVs, and LMA collaterals than 3.0 T TOF MRA (P<0.05 for both observers). The 5.0 T TOF MRA demonstrated superior detection capabilities. It showed higher MMV area scores, indicating better visibility of MMVs (z=4.41, P<0.001), and higher leptomeningeal system scores (z=3.72, P<0.001) compared to 3.0 T MRA.

Conclusions: The 5.0 T TOF MRA demonstrates potential as an assessment tool for MMA, providing enhanced visualization of abnormal vascular networks.