Imaging the Vulnerable Carotid Artery Plaque

Imaging plays a key role in the selection of patients for carotid artery surgery. Indication for carotid endarterectomy or stenting is based on symptomatology and degree of stenosis as determined by angiography, duplex ultrasonography or computed tomographic angiography. Degree of stenosis has long time been assumed the most reliable predictor of stroke-risk in patients with carotid artery stenosis and accordingly, traditional imaging methods were focused on luminal stenosis. There is, however, growing evidence that other factors than degree of stenosis determine whether a carotid plaque will result in acute neurologic events or not. Various morphological characteristics and molecular processes have proven to be highly related to carotid plaque instability and symptomatology. As a result, the focus of imaging techniques in carotid artery disease is more and more shifting towards identification of the vulnerable plaque rather than the high-grade stenosis. In traditional imaging modalities, new insights of imaging beyond degree of stenosis have been explored and may be able to detect morphological characteristics of plaque vulnerability. In addition, advanced molecular imaging methods have been developed and are able to identify molecular and cellular processes in the vulnerable carotid artery plaque. It is clear that recent developments in carotid imaging are of great potential in the identification of the vulnerable carotid plaque.