Abstract 55: Correlation Of Carotid Intraplaque Hemorrhage With Acute Territorial Cerebral Ischemic Events Using Magnetic Resonance Imaging
Background: Carotid intraplaque hemorrhage has been associated with clinical stroke symptoms and can be detected with MPRAGE (Magnetization-Prepared Rapid Acquisition with Gradient-Echo). Currently, there are no studies correlating carotid intraplaque hemorrhage (IPH) concurrent with acute territorial ischemic events defined by brain diffusion weighted imaging (DWI). Our aim was to determine the association of carotid intraplaque hemorrhage with acute territorial ischemic events using carotid MPRAGE and brain DWI.
Methods and Results: Carotid IPH was defined as at least 2-fold higher carotid MPRAGE signal intensity compared to adjacent sternocleidomastoid muscle. Using the MPRAGE sequence, IPH was identified with an accuracy of 91.2%, sensitivity of 91.3%, and specificity of 90.9% as compared to histology in 91 slides from 10 endarterectomy subjects. The Kappa values for interobserver and intraobserver agreement on MPRAGE signal were 0.806 and 0.818 respectively (very good agreement). After the addition of the MPRAGE sequence to the neck MRA protocol, 131 consecutive patients with suspected acute stroke were evaluated with both brain DWI and carotid MPRAGE sequences over the course of 1.5 years, providing 262 carotid artery and paired brain images for analysis. 34 arteries were excluded due to an extracarotid etiology of brain ischemia and 4 were excluded due to carotid occlusion. 224 arteries were eligible for data analysis. Carotid IPH was associated with acute territorial ischemic events with a relative risk of 4.1 (p<0.05). This is demonstrated by the representative image below depicting left carotid IPH as hyperintense MPRAGE signal (left) and an acute ischemic event in the left middle cerebral artery distribution with diffusion restriction on brain DWI (right). The relative risk of an ischemic event with carotid IPH was increased in mild, moderate and severe stenosis categories (5.1, 2.9, and 1.8, p<0.05).
Conclusion: In the workup of acute stroke, carotid IPH increased the risk of simultaneous territorial cerebral ischemic events in all carotid stenosis categories. By using objective data from brain DWI, accurate risk assessment of vulnerable plaque components can be obtained.
- © 2012 by American Heart Association, Inc.