Novel method of calculation of MRI perfusion and comparison of single versus double barrel STA-MCA bypass for revascularisation in Moya Moya disease

Introduction: Moyamoya disease (MMD) is characterised by supraclinoid internal carotid artery (ICA) narrowing causing cerebral parenchyma to starve. Direct and indirect revascularisation techniques are the treatment norm. We provide a clinicoradiological comparison of single and double barrel superficial temporal artery to middle cerebral artery (STA-MCA) bypass for MMD. The perfusion in cerebral hemispheres and vessel density in DSA have been evaluated using novel algorithms.

Methods: DSA, ASL MR imaging methods and Suzuki, Matsushima, Angiographic Outcome Score (AOS) scales were used to quantify perfusion parameters; modified Rankin score (mRS) was used for clinical evaluation. A novel image processing algorithm was designed to perform analysis of ASL sequences and compare perfusion. Vessel density was calculated using connected component analysis on thresholded DSA images.

Results: 54 hemispheres with MMD underwent STA-MCA bypass 42(77.8%) single barrel and 12 (22.2%) double barrel. Clinical outcome - mRS was significant with p<0.001 in single barrel and p=0.001 in double barrel groups. The overall AOS showed improvement post-operatively (p=0.032).Perfusion analysis was performed in 20 hemispheres (13 single barrel; 7 double barrel). MCA territories showed significant improvement in single barrel (2.72%, p=0.0294) and double barrel groups (12.89%, p=0.025). Vessel density calculated in MCA territory, showed an overall post-op improvement (p=1.75 x 10-8).

Conclusion: Double barrel STA-MCA bypass clinically as well as radiologically improves perfusion in the ACA as well as MCA territories in MMD. The novel image processing algorithm is an accurate, objective tool to evaluate perfusion in MR images and vessel density in DSA images of MMD.