Treatment Targets for Inflamed Intracranial Atherosclerosis on Vessel Wall MRI

Intracranial atherosclerosis (ICAS) accounts for 10 to 40%, depending on ethnicity, of the 700,000 ischemic strokes in the United States every year. The annual rate of recurrent stroke in patients with optimally treated ICAS remains more than twice the average of other stroke etiologies (12.5% vs. 5). A robust literature has established that vessel wall magnetic resonance imaging (vwMRI) of extracranial carotid vessel wall enhancement (VWE) can predict stroke, independent of stenosis. VWE has been reported in symptomatic ICAS, but the role of local and systemic inflammation is unknown. Inflammatory biomarkers are elevated in symptomatic extracranial atherosclerosis, but the association with vwMRI findings in ICAS has not yet been explored. VWE is typically demonstrated by the uptake of gadolinium MRI contrast into the aneurysm wall or atherosclerotic plaque. A novel MRI contrast agent, ferumoxytol, allows multi-contrast weighting on T1w and T2w images and provides important insight into the role of local vessel wall inflammation by accumulating in macrophages on delayed T2\* sequences. To identify effective prevention and treatment strategies for cerebrovascular disease, we need to critically evaluate vwMRI techniques, determine VWE prevalence, and explore the link between VWE and inflammation.