Standardized MR Perfusion Scoring System for Evaluation of Sequential Perfusion Changes and Surgical Outcome of Moyamoya Disease

Abstract

BACKGROUND AND PURPOSE: Simple-but-precise evaluation of cerebral perfusion is crucial for the treatment of Moyamoya disease. We aimed to develop a standardized scoring system for MR perfusion suitable for Moyamoya disease evaluation and investigate the postoperative serial changes and outcome predictors. MATERIALS AND METHODS: From January 2013 to December 2016, patients diagnosed with Moyamoya disease and receiving indirect revascularization were recruited prospectively. Clinical data and serial imaging studies were analyzed. The TTP maps were standardized using cerebellar reference values. We developed a scoring system of standardized TTP maps: 14 points for each hemisphere with higher points indicating better perfusion. RESULTS: In total, 24 children (4-17 years of age, 41 hemispheres) and 20 adults (18-51 years of age, 34 hemispheres) were included. The mean preoperative TTP scores were higher in children (7.34 Ϯ 3.90) than in adults (4.88 Ϯ 3.24). The standardized TTP maps revealed dynamic improvement with an increase in the corresponding scores at the 1-, 3-, and 6-month postoperative follow-ups; the scores stabilized after 6 months. The mean improvement in the 6-month scores of the pediatric and adult groups was 4.15 Ϯ 3.55 and 6.03 Ϯ 3.04, respectively. The 6-month TTP score improvements were associated with Matsushima grades. If we took score improvement as the outcome, the preoperative TTP score was the only significant predictor in multivariable analysis. CONCLUSIONS: The standardized TTP maps and scoring system facilitated the quantification of the sequential perfusion changes during Moyamoya disease treatment. The preoperative perfusion status was the only predictor of indirect revascularization outcome. ABBREVIATIONS: EDAS ϭ encephaloduroarteriosynangiosis; EPS ϭ encephalopericraniosynangiosis; MMD ϭ Moyamoya disease; MRP ϭ MR perfusion M oyamoya disease (MMD) is a progressive occlusive disease

Contemporary and emerging magnetic resonance imaging methods for evaluation of moyamoya disease

“…Using a simple qualitative visual analysis, Lin et al divided each cerebral hemisphere into 14 segments, normalized perfusion to the cerebellum, and assessed the TTP on each segment over time. 41 The TTP delay improved on serial examinations over a 6-month time period, and the improvement correlated with the Matsushima grade. 41 This or similar modifications can be applied to clinical practice.…”

“…41 The TTP delay improved on serial examinations over a 6-month time period, and the improvement correlated with the Matsushima grade. 41 This or similar modifications can be applied to clinical practice. Although such an approach is straightforward, consideration of multiple perfusion parameters likely provides a more complete, albeit descriptive, picture of clinical status.…”

“…Specifically, CVR may be used to monitor patients and determine when cerebrovascular reserve is waning and revascularization would be beneficial. 41 It may also be used to follow patients after revascularization. 38,41,78 In particular, patients with an intermediate disease stage (modified Suzuki stage II or III) have been found to have variable hemodynamics, and evaluation of CVR is of particular use to guide therapy.…”

“…41 It may also be used to follow patients after revascularization. 38,41,78 In particular, patients with an intermediate disease stage (modified Suzuki stage II or III) have been found to have variable hemodynamics, and evaluation of CVR is of particular use to guide therapy. 37 Evaluation of CVR before and after surgical revascularization has shown that reversal of a preoperative CVR impairment corresponds with collateral formation on DSA and successful revascularization.…”

“…Finally, perfusion and CVR have been applied to monitor success of revascularization. 70 Methods of systematic analysis of perfusion parameters have been proposed by Lin et al and Yun et al 41,78 While such assessment is not standardized, these authors normalized perfusion to the cerebellum and defined vascular territories for assessment. Using a simple qualitative visual analysis, Lin et al divided each cerebral hemisphere into 14 segments, normalized perfusion to the cerebellum, and assessed the TTP on each segment over time.…”