Non-invasive assessment of postoperative revascularization using slab MIP images in 3D TOF MRA in pediatric moyamoya disease

Purpose: Evaluation of angiogenesis and cerebral circulation after revascularization is essential in pediatric moyamoya disease, but conventional methods such as digital subtraction angiography (DSA) and single-photon emission computed tomography (SPECT) are invasive and unsuitable for repeated follow-up. We aimed to develop an objective scoring index based on slab maximum intensity projection (MIP) images obtained from three-dimensional time-of-flight (3D TOF) magnetic resonance angiography (MRA) and to examine its correlation with DSA findings and cerebral blood flow (CBF) changes after surgery. Methods: We retrospectively analyzed 45 hemispheres in 28 pediatric patients who underwent revascularization between 2010 and 2023. Cortical angiogenesis was evaluated using slab MIP images before and after surgery, and scored using a modified Alberta Stroke Program Early CT Score (moya-ASPECTS). Associations with Matsushima grade, CBF and cerebrovascular reserve (CVR) measured by SPECT, and regression of moyamoya vessels were assessed. Results: The moya-ASPECTS score showed a strong correlation with Matsushima grade (P < 0.001). Postoperative resting CBF increased by 2.27 ml/100 g/min for each point increase in moya-ASPECTS (95% CI 0.87–3.67, P = 0.003). While moya-ASPECTS was not associated with CVR change, it correlated significantly with regression of moyamoya vessels (RR 1.33, 95% CI 1.12–1.58, P < 0.001). Higher moya-ASPECTS scores were inversely associated with postoperative asymptomatic infarction, although the number of events was small. Conclusion: The moya-ASPECTS score derived from slab MIP images provides a non-invasive, repeatable, and semi-quantitative method for evaluating postoperative cortical collateral formation in pediatric moyamoya disease. This method correlates well with DSA and CBF improvement, offering a practical alternative for long-term outpatient follow-up.