Clinical and Histological Significance of Gadolinium Enhancement in Carotid Atherosclerotic Plaque

Abstract

Background and Purpose-Although the ability of MRI to investigate carotid plaque composition is well established, the mechanism and the significance of plaque gadolinium (Gd) enhancement remain unknown. We evaluated clinical and histological significance of Gd enhancement of carotid plaque in patients undergoing endarterectomy for carotid stenosis. Methods-Sixty-nine patients scheduled for a carotid endarterectomy prospectively underwent a 3-T MRI. Carotid plaque enhancement was assessed on T1-weighted images performed before and 5 minutes after Gd injection. Enhancement was recorded according to its localization. Histological analysis was performed of the entire plaque and of the area with matched contrast enhancement on MR images. Results-Gd enhancement was observed in 59% patients. Three types of carotid plaques were identified depending on enhancement location (shoulder region, shoulder and fibrous cap, and central in the plaque). Fibrous cap rupture, intraplaque hemorrhage, and plaque Gd enhancement was significantly more frequent in symptomatic than in asymptomatic patients (P=0.043, P<0.0001, and P=0.034, respectively). After histological analysis, Gd enhancement was significantly associated with vulnerable plaque (American Heart Association VI, P=0.006), neovascularization (P<0.0001), macrophages (P=0.030), and loose fibrosis (P<0.0001). Prevalence of neovessels, macrophages, and loose fibrosis in the area of Gd enhancement was 97%, 87%, and 80%, respectively, and was different depending on the enhancement location in the plaque. Fibrous cap status and composition were different depending on the type of plaque. Conclusions-Gd enhancement of carotid plaque is associated with vulnerable plaque phenotypes and related to an inflammatory process. (Stroke. 2012;43:3023-3028.)

Contemporary carotid imaging: from degree of stenosis to plaque vulnerability

“…Prior studies have demonstrated that plaque enhancement on DCE MRI is significantly associated with ipsilateral ischemic events, independent of degree of stenosis. 64,74 These studies are in accord with previous reports demonstrating the increased expression of the angiogenic pathway in unstable plaques, thus underscoring the seminal role of plaque neovascularization in plaque vulnerability. A summary of imaging characteristics of vulnerable plaques on MRI is provided in Table 2.…”

Imaging of the Carotid Artery Vulnerable Plaque

“…Moreover, they showed that early plaque enhancement is due to the presence of internal neovessels, while late enhancement is related neovasculature supply and endothelial permeability [94]. The correlation between the degree of plaque enhancement and the degree of neovascularization, which is itself linked to the degree of plaque inflammation, also was confirmed at histology in a recent study by Millon et al [96].…”

Gadolinium Enhancement of Atherosclerotic Plaque in the Middle Cerebral Artery: Relation to Symptoms and Degree of Stenosis

“…[7][8][9][10] An association between carotid plaque enhancement and clinical symptoms has been observed in several recent investigations by using Gd-enhanced MR imaging. 9,11 In contrast to the numerous investigations that have been performed on the carotid artery, only a few studies performed on a small number of patients have focused on the clinical significance of Gd enhancement of plaques in the setting of ICAD. [12][13][14] These studies identified a significant association between plaque en-hancement on ICAD and ischemic events.…”