Estimation of Severity of Moyamoya Disease with [15O]Water-Positron Emission Tomography Compared with Magnetic Resonance Imaging and Angiography

Abstract

Background: Moyamoya disease is a steno-occlusive disease of the circle of Willis with growth of pathologic collaterals. We compared functional perfusion imaging ([¹⁵O]water-positron emission tomography [PET] with acetazolamide challenge) with conventional magnetic resonance imaging (MRI) and angiography for determining indication for cerebral revascularization in patients with moyamoya.

Methods: We performed a retrospective blinded analysis of individual imaging modalities (MRI, angiography, PET) and scored each modality for severity of disease in 21 untreated patients with moyamoya with 78 affected vascular territories.

Results: Positive predictive value to identify insufficient perfusion on angiography and MRI together was 98.3% as proven on combined PET/computed tomography. Negative predictive value to identify sufficient perfusion on angiography and/or MRI only was 60%. Negative predictive value to predict good perfusion on PET based on MRI (no infarctions in the respective territory) was only 17%. An assumed good perfusion based on the suggestion of good collaterals on angiography was correct in only 13.4% of cases. Positive predictive value (angiography of main vessel and weak or no collateralization) to predict insufficient perfusion on PET/computed tomography was 76.9%; negative predictive value (angiography of main vessel and strong collateralization) to identify good perfusion was 13.4%.

Conclusions: Reliable evaluation of cerebral blood flow might not be possible with angiography and basic MRI alone. We strongly recommend additional functional imaging (e.g., [¹⁵O]water-PET with acetazolamide challenge) to precisely evaluate the indication for cerebral revascularization.

Keywords: Cerebral revascularization; Moyamoya disease; Positron emission tomography.