Detection of unstable carotid plaque in ischemic stroke prevention

Atherosclerotic carotid stenosis is a well-known risk factor for ischemic stroke or transient ischaemic attack. Atherosclerotic plaque features, such as intraplaque hemorrhage, neovascularization, large lipid core, thin or ruptured fibrous cap or inflammation seem to play an important role in plaque instability and are related to higher risk of ischaemic stroke. At present, no single modality is able to accurately measure the degree of stenosis and to detect all vulnerable plaque features simultaneously. For accurate and detailed analysis of plaque morphology, the combination of particular methods should be used. CT is widely available and often the first imaging modality used, with the strength to detect plaque calcifications, ulceration and degree of stenosis but differentiation between lipid pools and intraplaque hemorrhage is low. MRI can identify most of the plaque's unstable features but time constraints, movement artifacts and absence of a unified procedure are complications for wider use. PET is an effective tool to detect metabolic processes in plaque mainly due to inflammation but spatial resolution is imprecise. Ultrasound is a widely available, low-cost tool for monitoring plaque development especially if 3D mode is applied, but for plaque characteristic differentiation, it is suboptimal. Future development of ultrasound methods, i.e. computerized analysis of Gray scale and contrast enhancement improves the ultrasound's potential significantly.