Abstract 2640: The Size of Lipid-Rich Necrotic Core and Presence of Hemorrhage are Associated with Fibrous Cap Status in Carotid Atheroma: A 3T Magnetic Resonance Imaging Study

Abstract

Purpose: Histology studies of carotid specimens suggest an association between lipid-rich necrotic core (LRNC) size, hemorrhage, and fibrous cap status. However, these studies represent a select population with advanced atherosclerosis. This study investigates whether LRNC size and hemorrhage are associated with cap status in moderate to advanced stage carotid atherosclerosis using 3T MRI.

Methods: Seventy seven patients from Anzhen Hospital with > 50% stenosis in at least one carotid artery underwent bilateral carotid MRI scans with TOF-/T1-/T2-/PD-/gadolinium-enhanced T1-weighted axial imaging. Arteries with poor image quality (3), occlusion (6), calcium nodules (3) or no detectable LRNC (37) were excluded. Five reviewers measured the vessel wall, LRNC, and hemorrhage, and identified fibrous cap status (thick, thin, or ruptured). The worst fibrous cap status across all cross sections was used to classify the vessel. The %-LRNC (LRNC area divided by wall area) and %-hemorrhage was calculated and mean values of maximal %-LRNC and %-hemorrhage were compared between cap status groups (thick, thin, or ruptured).

Result: Distributions of the 105 arteries were 42 (40%), 47 (45%), and 16 (15%), for thick, thin, and ruptured cap groups, respectively. Mean values ± SD of maximal %-LRNC were 21.8±12.7, 38.6±12.9, and 52.8±13.8, in thick, thin, and ruptured cap groups, respectively. The mean (across arteries) of the maximum % LRNC in each artery differed significantly when arteries were grouped by cap status. Comparison of means using analysis of variance with Bonferroni’ adjustment for post hoc comparisons showed significant differences in means between thick and thin cap groups (p<0.01), thick and ruptured cap groups (p<0.01), and thin and ruptured cap groups (p<0.01). Hemorrhage was found in 9 arteries with thin cap, and in 14 arteries with ruptured cap. No artery had hemorrhage in the thick cap group. Mean values of maximal %-hemorrhage for the thin and ruptured groups were similar and not statistically different.

Conclusion: Amongst mainland Chinese with carotid atherosclerosis, the size of the LRNC core was associated with fibrous cap status. Presence of hemorrhage was associated with thin or ruptured cap.