New grading of moyamoya disease using color-coded parametric quantitative digital subtraction angiography

Background: Moyamoya disease (MMD) is an uncommon cerebrovascular disorder characterized by idiopathic progressive stenosis or the occlusion of the intracranial arteries. Digital subtraction angiography (DSA) is the reference diagnostic imaging modality for MMD. Use of the conventional Suzuki grading remains the gold standard for evaluating the severity of MMD. In this study, we propose a quantitative method using color-coded parametric quantitative DSA (QDSA) to improve prediction of the severity of MMD. Methods: Eighteen DSA examinations from 18 patients with MMD and 14 control participants were included. All patients with MMD underwent DSA and dynamic susceptibility contrast perfusion-weighted imaging (DSC-PWI). QDSA was used to determine the delay time of maximal opacification (Td) between the internal carotid artery and the M2 segment of the middle cerebral artery. The time-to-peak (TTP) was measured in the medial frontal, lateral frontal, parietal, and occipital lobes from the DSC-PWI. The relative TTP (rTTP) values were then obtained by subtracting the TTP of the cerebellum. Results: The Td was significantly longer in the patients with MMD presenting with infarction than in the control group. The Td significantly correlated with the angiographic Suzuki grading system and showed closer correlation with prolonged rTTP in the medial frontal, lateral frontal, and parietal regions compared with Suzuki grading. Conclusion: The Td significantly correlated with conventional angiographic grading and with the status of hemodynamic impairment in patients with MMD. QDSA and Td measurements can provide a simple and quantitative angiographic grading system for patients with MMD.