Abstract 19023: Association between Intraplaque Hemorrhage and Two Plaque Burden Measurements: Maximum Wall Thickness and Luminal Stenosis
Background: Intraplaque hemorrhage (IPH) has been shown to be a high risk plaque feature. It is well known that angiography underestimates plaque burden due to expansive remodeling and the unique geometry of the carotid bulb. As such, vessel wall imaging should provide a better method of screening for high-risk plaque features than measurement of stenosis. Multi-contrast carotid wall magnetic resonance imaging (MRI) is able to depict vessel wall morphology and components accurately. We tested the hypothesis that vessel wall thickness measured by carotid wall MRI has a stronger correlation with IPH than luminal stenosis.
Methods: Patients with suspected carotid disease or those with asymptomatic plaques detected by ultrasound were referred for a multi-contrast MRI of their carotids. Lumen and outer wall boundaries for each axial slice were traced using a custom-designed image analysis software to calculate maximum wall thickness (MWT). The presence and percent volume (IPH volume/wall volume×100%) of IPH were recorded. Luminal stenosis was measured according to NASCET criteria on 3D time-of-flight MR angiography. Receiver operating characteristic (ROC) analysis was used to compare the discriminating strengths of MWT and luminal stenosis for presence of IPH. Correlation between the two indexes and percent volume of IPH was assessed with Pearson correlation coefficient (r).
Results: Of the 83 patients scanned, 7 were excluded during image review due to occlusion or insufficient coverage of the index side artery. The area under the ROC curve of MWT for predicting IPH was significantly greater than luminal stenosis (0.83 vs 0.70, p=0.016). In the subgroup of patients with IPH (n=26), MWT showed a stronger correlation with percent volume of IPH than luminal stenosis (r=0.78, 95% CI: 0.56–0.89 vs r=0.57, 95% CI: 0.24–0.79, p<0.001).
Conclusion: This study demonstrated that MWT as a direct burden measurement produced from vessel wall imaging works better than measurement of stenosis in predicting IPH. This finding provides further evidence that carotid wall imaging provides a better tool to screen for the presence of high risk carotid atherosclerosis.
- © 2010 by American Heart Association, Inc.