Abstract 3635: Prevalence of AHA Type VI Carotid Lesions Identified by MRI Across Different Categories of Stenosis Measured by Duplex Ultrasound
PURPOSE: To determine the prevalence of complicated AHA Type VI atherosclerotic lesions (plaques with luminal surface defect, hemorrhage/thrombus or calcified nodules) in the carotid artery via MRI for different levels of stenosis as measured by duplex ultrasound (US).
MATERIAL & METHODS: 185 consecutive subjects had their bilateral carotid arteries scanned with a 1.5T-scanner using TOF-/T1-/PD-/T2-weighted images after evaluation with US to determine stenosis. Arteries with previous endarterectomy, image quality < 3 on MRI, or missing ultrasound data were excluded. In total, 260 arteries were available for analysis. 2 experienced carotid MRI reviewers determined the AHA lesion type, and identified the presence or absence of hemorrhage, fibrous cap rupture, calcified nodules and thrombus.
RESULTS: Prevalence of AHA lesion type VI was 8.1% in the 37 arteries with 1–15% stenosis, 21.7% in the 60 arteries with 16–49% stenosis, 36.8% in the 114 arteries with 50–79% stenosis and 77.6% in the 49 arteries with 80–99% stenosis (see figure⇓). In total, 402 MR locations with AHA lesion type VI were identified. The most common reason for a lesion to be classified as a Type VI lesion was hemorrhage (65.7%), followed by fibrous cap rupture (26.4%) and others (7.7%).
CONCLUSIONS: Complicated AHA Type VI lesions are frequently found in arteries with <50% stenosis. These findings indicate the importance of vessel wall imaging for identification of culprit lesions. Ongoing prospective studies will determine the predictive value of vulnerable plaque features, as visualized by MRI, for risk of subsequent ischemic events.