Abstract W P119: High Resolution MRI Characteristics of Unclassified Intracranial Stenosis Under Age 50

Abstract

Introduction: Intracranial stenoses in the young have various underlying pathologies, including early atherosclerosis, infectious and inflammatory vasculitis, and Moyamoya disease, but specific diagnosis is challenging in clinical practice. We set out to characterize the unclassified intracranial stenoses and probable atherosclerosis in the young using high-resolution MRI (HR-MR) vessel wall imaging techniques. Methods: We reviewed the HR-MR database at our hospital with criteria of patients under 50 years with intracranial stenosis. Patients with primary / secondary CNS vasculitis, infectious vasculitis, Moyamoya disease, dissection or cardio embolic strokes were excluded. Imaging protocol included black-blood gadolinium contrast -enhanced T1-weighted sequence with fat suppression and time-of-flight MRA of the circle of willis with 3-Tesla MRI. Results: Twenty-five patients (9 males, median age 41) met the inclusion criteria. Hyperlipidemia hypertension, history of smoking and diabetes mellitus were noted in 24, 20, 16, and 9 patients respectively. Seventeen had 3 or more vascular risk factors. Twenty-one patients (84 %) had isolated anterior circulation involvement, while 13 patients (52%) had single vessel stenosis. Median time interval between ischemic event and HR-MR was 78 days. Concentric vessel wall enhancement of the culprit stenosis was noted in 18 patients (72%). None had eccentric wall thickening and eccentric enhancement. Vessel wall enhancement was associated with the presence of diabetes (p=0.026) but not associated with other vascular risk factors. Having a risk factor burden of 3 or more (p=0.15), multifocal stenosis (p=0.3), or shorter time to MRI imaging (p=0.6) were not associated with vessel wall enhancement. On follow-up HR-MR imaging after median of 6 months, all 5 patients with early vessel wall enhancement had unchanged findings. Conclusion: In this cohort, while the risk factor burden suggests “accelerated atherosclerosis,” the vessel wall enhancement patterns are unlike atherosclerotic plaques that have been previously described with HR-MR. The nature of these stenoses needs further investigation.