Introduction: Moyamoya is a chronic arterio-occlusive disease that affects the cerebrovasculature of the anterior circulation presenting with ischemic and/or hemorrhagic symptoms. Due to progressive vessel stenosis, collateralization is required to compensate for decreased blood flow distal to diseased vessels. This results in ipsilateral collateral flow development through the PCA and ACA vessels that can be measured by QMRA.

Methods: Moyamoya is a chronic arterio-occlusive disease that affects the cerebrovasculature of the anterior circulation presenting with ischemic and/or hemorrhagic symptoms. Due to progressive vessel stenosis, collateralization is required to compensate for decreased blood flow distal to diseased vessels. This results in ipsilateral collateral flow development through the PCA and ACA vessels that can be measured by QMRA.

Results: The mean hemispheric flow deficit was 68.4 cc/min with a standard deviation of 29.5 with all 5 patients demonstrating the greater flow to the disease free hemisphere. In contrast, the mean pial collateral flow was 71 cc/min with a standard deviation of 33.7 in which all 5 patients had a increased flow to the diseased hemisphere.

Conclusions: To our knowledge NOVA has not been previously used to describe pial collateral flows in a population of only moyamoya disease patients. The significance of using NOVA in this fashion is to determine the compensatory abilities of the PCA and ACA2 vessels by revealing the increase in flow in the ipsilateral vessels in comparison to the contralateral vessels. This may eventually show NOVA as a key study in determining ideal patients for revascularization surgery via either direct or indirect bypass.

Patient Care: Utilizing QMRA in patients with diseases of the cerebrovasculature may eventually shed light on patients that may best be suited for a revascularization surgery. This study's current goal is to demonstrate the underlying flow dynamics in a patient with diseased intracranial vessels and how we can better understand hemispheric flow relationships as well as collateralization, wtihout invasive studies such as angiograms or intra-operative flow probes.

Learning Objectives: Utilization of QMRA and to advance the understanding of the pial collateral networks in moyamoya disease

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