Tc99m-ECD brain SPECT in patients with Moyamoya disease: A reflection of cerebral perfusion status at tissue level in the disease process

BACKGROUND: Moyamoya disease is a rare, progressive cerebrovascular disorder caused by intracranial stenosis of the circle of Willis, resulting in successive ischemic events. Computed tomography (CT) and magnetic resonance imaging (MRI) play a major role in diagnosis. OBJECTIVE: The aim of the study was to describe the spectrum of findings on brain SPECT in patients with Moyamoya disease and to compare the findings with other investigations. MATERIALS AND METHODS: Tc99m-ECD SPECT scans of seventeen patients (7 children and 10 adults) were analysed to study the brain perfusion. RESULTS: Features of Moyamoya disease were detected on DSA in 11 patients, CTA in one, MR angiography in one patient. Brain perfusion SPECT analysis showed unilateral perfusion defects in 11 patients, normal perfusion in 2 and bilateral defects in 4 patients. No perfusion defects despite bilateral vascular changes were noted in one patient. Cerebral infarcts were detected on MRI unilaterally in three subjects while multiple infarcts were identified in one. Tc99m-ECD Brain SPECT showed perfusion defects that were more extensive compared to those detected on MRI. Post acetazolamide studies for assessment of cerebrovascular reserve were done in three patients. Two of them showed good cerebrovascular reserve (>1). Follow-up studies post-surgical procedures (Myo-dura synangiosis) done in two patients showed partial resolution of perfusion defects in the involved areas. CONCLUSION: Brain perfusion scintigraphy is an important adjunct in evaluation of patients with Moyamoya disease yielding information about the direct end results of the pathology in the vessels and also prognostic information.