MRI Assessment of Oxygen Metabolism and Hemodynamic Status in Symptomatic Intracranial Atherosclerotic Stenosis: A Pilot Study

Abstract

Hemodynamic and metabolic impairment in intracranial atherosclerotic stenosis (ICAS) may promote stroke vulnerability particularly in borderzone areas. Perfusion and oxygen mapping magnetic resonance imaging (MRI) may provide useful information in this setting. In this pilot study, patients with symptomatic atherosclerotic anterior circulation stenosis ≥60%, without other sources of ischemic stroke, were included. High-resolution vessel wall MRI quantified the stenosis degree, and hemodynamic and metabolic impairment was assessed at baseline using dynamic susceptibility contrast perfusion and multiparametric quantitative blood-oxygen-level-dependent (mqBOLD) oxygenation MRI. All parameters were assessed within both hemispheres and in borderzone areas. Forty-three subjects with intracranial artery narrowing were screened from November 2014 to January 2016. Eleven patients met the study criteria (mean ± standard deviation age = 64.4 ± 10.6 years, the mean degree of stenosis was 76.9 ± 23.4%). No interhemispheric differences were observed across oxygen (cerebral metabolic rate of oxygen and tissular saturation of oxygen) or perfusion (mean transit time, time to maximum, Tmax , normalized cerebral blood volume [nCBV], and normalized cerebral blood flow) parameters. A positive correlation was observed between the stenosis degree and ipsilateral nCBV (R = .77, P = .008). In addition, a significant increase in CBV was observed in anterior cortical borderzones ipsilateral to stenosis (nCBV = 7.20 ± 1.81 vs. 5.45 ± 1.40 mL/100 g, P = .02). Symptomatic ICAS had no global impact on perfusion and oxygen mapping MRI at resting state. A significant increase in nCBV was found within anterior borderzone areas.