Introduction: Moyamoya disease (MMD) is a steno-occlusive disease of the anterior cerebral arterial circulation. Patients present when there is a failure in the pial or subcortical neo-collateral networks. The mainstay of therapy is a direct bypass, an encephaloduroarteriosynangiosis (EDAS; indirect bypass), or a combined approach. We assessed pre and postoperative collateral flow using quantitative magnetic resonance angiography (qMRA) to find a value that would indicate effective versus ineffective collateral.

Methods: Patients with angiographic evidence of moyamoya disease between January 2010 and January 2016 were identified to be included in the study. Only patients with pre and postoperative qMRAs qualified. The difference of preoperative [ACA + PCA] and postoperative [ACA + PCA] flow yields the collateral burden. The collateral burden, then in relation to the preoperative flow determines the percent change of the burden from the preoperative state. Patients were grouped based on type of bypass: EDAS or direct (including direct in combination with EDAS).

Results: Forty-Six patients were diagnosed with MMD. Of those, eighteen patients underwent 19 revascularization procedures with qMRA. A total of 6 EDAS, 6 direct STA-MCA bypasses and 7 combination STA-MCA + EDAS revascularizations were performed. Patients who underwent direct or combination bypasses showed on average a decrease of 28ml/min postoperatively (p<0.05), which equates to a 16% decrease of preoperative collateral burden. The 6 patients who underwent EDAS did not show a statistically significant decrease in collateral burden; however there were only 6 patients and 5/6 patients had qMRA prior to bypass maturation.

Conclusions: Quantitative MRA allows noninvasive measure of blood flow within the intracranial vessels. Comparing preoperative to postoperative flow values in patients with moyamoya disease may have the ability to quantify the success of revascularization surgery. We defined and calculated the collateral burden value, which may be useful in determining a surgery’s success on revascularizing a patient’s cerebrovascular flow.

Patient Care: This research provides initial attempts at determing a method to predict patient outcomes in patients with revascularization for Moyamoya disease. It also functions to describe a potential method of comparing effectiveness of direct and indirect revascularization procedures.

Learning Objectives: By Conclusion of this session participants should b able to: 1) Understand the function of collateral flow in patients with moyamoya disease 2) Describe the value of qMRA NOVA in guiding management of moyamoya disease 3) Discuss how newer imaging modalities have the potential to measure comparative efficacy between different surgical revascularization procedures in moyamoya disease .

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