Imaging of carotid plaque

The prelims comprise: Carotid plaque morphology is an important risk factor for stroke and TIA. "Vulnerable Plaque" shows lipid-rich (necrotic) core covered by a thin fibrous cap, plaque inflammation, neovascularization (angiogenesis), hemorrhage, microcalcification, and adventitial inflammation. DSA has limited role in evaluation of plaque as it lacks the sensitivity and specificity to characterize the chemical/ histological composition of the plaque. Patients with an echolucent and heterogeneous plaque on ultrasound, have a higher risk of developing neurologic events than patients with homogeneous, echorich plaques. Hypodensity (<30HU) in the center of carotid plaque is suggestive of presence of lipid, hemorrhage, or necrotic debris, markers for vulnerable plaque. On high resolution MR, black-blood technique with fat and flow suppression enables the visualization of the vessel wall and histological characteristics of the plaque while bright blood method is suitable for visualizing the vessel wall, surface ulcerations, fibrous cap thickness and identification of calcified nodules.