Plaque vulnerability in internal carotid arteries with positive remodeling

Abstract

Background: This study aimed to evaluate the efficacy of assessing positive remodeling for predicting future stroke events in the internal carotid artery. We therefore assessed narrowing of the carotid artery lumen using multidetector-row computer tomography (MDCT) angiography and carotid plaque characteristics using black-blood (BB) magnetic resonance (MR).

Methods: We retrospectively selected 17 symptomatic and 11 asymptomatic lesions with luminal narrowing >50%. We compared remodeling parameters of luminal stenosis (remodeling ratio, RR/remodeling index, RI) using MDCT and MR intensities of atherosclerotic plaque contents using the BB technique (relative signal intensity, rSI). We also confirmed the validity of the relationship between MR intensity and atherosclerotic plaque contents by histology. The levels of biological markers related to vessel atherosclerosis were measured.

Results: Plaque lesions with positive remodeling in carotid arteries were associated with a significantly higher prevalence of stroke compared with plaques with negative remodeling (p < 0.05). Radiologic and histologic analyses determined that plaques with positive remodeling had higher signal intensities (with respect to their lipid-rich content or to hemorrhage) compared with negative remodeling (correlation coefficients: RI and rSI, r = 0.41, p < 0.05; RR and rSI, r = 0.50, p < 0.05). Levels of biological markers, including high-sensitivity C-reactive protein, hemoglobin A1C, total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol, were not useful for predicting stroke events.

Conclusions: The results of this study suggest that the combined analysis of RR, RI and rSI could potentially help to predict future stroke events.

Keywords: Black-blood magnetic resonance image; Carotid artery; Multidetector-row computer tomography; Plaque vulnerability; Positive remodeling.

Fig. 1

Patient screening. Forty-two participants who underwent both MDCT angiography and BB MR analysis were identified in the Nagoya City University Medical Center database from August 2008 to July 2010; 50 arteries were excluded because of stenosis <50% in NASCET, and 6 arteries were excluded because of the presence of other potential causes of neurologic symptoms (full occlusion, 3 arteries, and possible dissection, 3 arteries). Twenty-eight arteries were finally enrolled in this study; 10 of the 28 were treated surgically (CEA).

Fig. 2

MDCT angiography and BB MR analysis. The degree of luminal stenosis in the carotid arteries was evaluated from axial images and curved multiplanar reconstruction following NASCET criteria (A, C). After identifying the atherosclerotic lesions, serial cross-sectional images of the carotid arteries were obtained by altering the z-axis to allow analysis of the nearest distal (B) and proximal portions (D) without atherosclerotic plaque lesions. The outer vessel contour was manually traced to calculate the cross-sectional vessel area in each portion, and a mean reference CSA value was calculated. Plaque remodeling of carotid arteries was assessed using both RI and RR. On MRI, signal intensity of the plaque lesion of interest was calculated relative to the signal intensity to the sternocleidomastoid muscle on T1WI (E). At = Anterior; P = posterior; L = left; R = right.

Fig. 3

Correlations between rSI and RI (A)/RR (B) were calculated, and significant correlations were found between both RI and rSI (r = 0.41, p = 0.03), and between RR and rSI (r = 0.50, p = 0.01).