Abstract 274: In Vivo Assessment of Adventitial Vasa Vasorum in Patients with Symptomatic Carotid Plaques: A Dynamic Contrast-Enhanced MR Imaging Study

Abstract

Objectives: To characterize adventitial vasa vasorum (VV) in unilaterally symptomatic patients and evaluate its association with intraplaque hemorrhage (IPH) and symptom status. Background: Adventitial VV is thought to be a primary source of IPH and a potential marker for plaque instability. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has been shown capable of quantifying adventitial VV in the carotid artery. Methods: Patients with ischemic cerebrovascular symptoms within the past 6 months and ipsilateral carotid plaques underwent MR imaging examination, which included a multi-contrast protocol for detecting IPH and a DCE-MRI protocol for measuring adventitial VV. Both the symptomatic and contralateral asymptomatic arteries were studied. Adventitial VV was measured at consecutive slices as adventitial Ktrans from kinetic modeling. Maximum adventitial Ktrans across all slices were calculated for each artery. Results: From the 27 patients (22 men; 69±10 years) recruited, 50 arteries had adventitial Ktrans measurements. IPH arteries (0.142±0.042 vs. 0.112±0.029 min-1, p<0.001) and symptomatic arteries (0.134±0.038 vs. 0.107±0.027 min-1, p=0.001) were shown to have higher adventitial Ktrans compared to their counterparts. In multivariate analysis, IPH, symptom status and male sex were independently associated with adventitial Ktrans. Conclusions: Adventitial VV demonstrated significant associations with IPH and symptom status. In vivo assessment of adventitial VV by DCE-MRI may be useful in studying plaque pathogenesis or risk stratification, but further examination through prospective studies is needed.