Background and purpose: Preliminary studies suggest that intracranial arteries are capable of accommodating plaque formation by remodeling. We sought to study the ability and extent of intracranial arteries to remodel using 3-dimensional high-resolution black blood magnetic resonance imaging and investigate its relation to ischemic events.
Methods: Forty-two patients with cerebrovascular ischemic events underwent 3-dimensional time-of-flight magnetic resonance angiography and contrast-enhanced black blood magnetic resonance imaging examinations at 3 T for intracranial atherosclerotic disease. Each plaque was classified by location (eg, posterior versus anterior circulation) and its likelihood to have caused a stroke identified on magnetic resonance imaging (culprit, indeterminate, or nonculprit). Lumen area, outer wall area, and wall area were measured at the lesion and reference sites. Plaque burden was calculated as wall area divided by outer wall area. The arterial remodeling ratio (RR) was calculated as outer wall area at the lesion site divided by outer wall area at the reference site after adjusting for vessel tapering. Arterial remodeling was categorized as positive if RR>1.05, intermediate if 0.95≤RR≤1.05, and negative if RR<0.95.
Results: One hundred and thirty-seven plaques were identified in 42 patients (37% [50] posterior and 63% [87] anterior). Compared with anterior circulation plaques, posterior circulation plaques had a larger plaque burden (77.7±15.7 versus 69.0±14.0; P=0.008), higher RR (1.14±0.38 versus 0.95±0.32; P=0.002), and more often exhibited positive remodeling (54.0% versus29.9%; P=0.011). Positive remodeling was marginally associated with downstream stroke presence when adjusted for plaque burden (odds ratio 1.34, 95% confidence interval: 0.99-1.81).
Conclusions: Intracranial arteries remodel in response to plaque formation, and posterior circulation arteries have a greater capacity for positive remodeling and, consequently, may more likely elude angiographic detection. Arterial remodeling may provide insight into stroke risk.
Keywords: MRI; atherosclerosis; intracranial arteriosclerosis; stroke; vascular remodeling.
© 2016 American Heart Association, Inc.