Abstract TMP53: MR-ASL Imaging Can Predict the Collaterals in Moyamoya Disease

Abstract

Introduction: Digital subtraction angiography (DSA) is the gold standard investigation for the diagnosis and prognostication of moyamoya disease (MMD). Magnetic resonance arterial spin labelling (MR-ASL) is a newer non-invasive technique that can predict the perfusion reliably. Our study aims at prediction of collaterals with MR-ASL in addition to parenchymal perfusion deficit. Methodology: It is an observational single centre cohort study where consecutive MMD patients with both DSA and MR-ASL done within 3 months of each other were included in the study. Images were reviewed by 2 radiologists independently. MMD severity was graded using Suzuki staging and collaterals were graded using DSA and MR-ASL in 7 different regions [4 areas in basal ganglia level - basal ganglia, M1, A1 and P1], 3 areas at superficial cortical level above basal ganglia [M2, A2, P2]. DSA collateral grading used was: grade 0 - no collaterals visible (absence of any capillary blush) with perfusion deficit, grade 1 - mild to moderate collaterals with some perfusion deficit, grade 2 - extensive collaterals with no perfusion deficit, grade 3 - normal antegrade flow. Collateral grading used on MR-ASL was: grade 0 - no or minimal ASL signal; grade 1 - moderate ASL signal with arterial transit artefact (ATA), grade 2 - high ASL signal with ATA, grade 3 - normal perfusion without ATA. Results: Of the 46 MMD patients (males - 22), 92 hemispheres were included. 4 hemispheres were excluded as the patient underwent revascularisation in the corresponding hemisphere. Among the remaining 88 hemispheres, 7 were normal on angiography. At various Suzuki grades, the degree of collaterals graded on ASL changed according to Suzuki staging (p<0.001). Whether collateral grading using ASL can predict the collaterals graded using DSA was tested using Cohen Kappa’s method, and it was found that MR-ASL can predict collaterals graded by DSA with very good agreement in all the regions studied (p<0.001). Conclusion: MR-ASL is a simple, safe, effective and reproducible alternative for DSA in determining the collaterals and perfusion status in MMD patients without the untoward effects like contrast exposure.