Carotid atherosclerotic disease is a principal cause of stroke. Advances in MRI have afforded the opportunity to study the in vivo evolution of plaque progression, monitor response to therapy during clinical trials, and identify features associated with future ischemic events such as fibrous cap rupture (FCR) and intraplaque hemorrhage (IPH). While carotid MRI is promising as an imaging modality to have a profoundly positive impact on the management of carotid disease, the complexity of image interpretation for the reliable detection of high-risk features such as IPH and FCR has limited its translation to clinical practice.

In our article, we sought to identify associations between more easily detected plaque features (ie, plaque morphology, calcification, lipid-rich necrotic core [LRNC], etc) and IPH and FCR. We found a strong association between size of the LRNC and the presence of IPH, FCR, or both. Subsequently, we constructed a simple ranking system, the Carotid Atherosclerosis Score (CAS), to stratify lesion severity based on presence and size of the LRNC. The principal strength of CAS is that the size of the LRNC, a metric that is highly reproducible, proved to be an effective surrogate for the presence of a high-risk lesion. In addition, the study included participants from 4 different institutions that were located in the United States and China suggesting that CAS is relatively robust across ethnicity and institution.

 

 

 

In follow-up to this article, we sought then to determine if CAS could predict the development of IPH, FCR, and plaque progression. In a recent prospective study (Xu et al, "Prediction of High-Risk Plaque Development and Plaque Progression with the Carotid Atherosclerosis Score: A Prospective MRI Study," JACC Cardvasc Imaging, in press), we found a significant increasing relationship between CAS and the development of new FCR and progression of plaque burden. In both the original study (Underhill et al) and the more recent prospective study (Xu et al), CAS outperformed stenosis, the conventional criterion for assessing carotid disease severity. Collectively, these results provide compelling evidence that CAS may have an important clinical role in evaluating patients with carotid atherosclerotic disease, regardless of stenotic severity.

Moving forward, we hope to further simplify the carotid MRI review process by developing an automated version of CAS. At RSNA 2013, we will be presenting prospective data (Hippe et al, "Automated Interpretation of Carotid Plaque Composition Identifies High-Risk Lesions: A Prospective MRI Study") on an algorithm that automatically measures LRNC size and calculates CAS for the carotid artery. This new study should move CAS a necessary step closer towards integration into clinical practice.

 

Read this article at AJNR.org . . .