Noninvasive Ultrasound Assessment of Atherosclerotic Plaques: From Anatomical Insights to Recent Technical Advances

Atherosclerosis is responsible for arterial obstruction and its clinical consequences and can be explored routinely with ultrasound techniques. Ultrasonographic indices (such as the degree of stenosis) have long been included in clinical guidelines on predicting the risk of harmful clinical events and guiding clinical decisions. Given the high availability of ultrasound imaging, a growing number of asymptomatic patients with atherosclerotic plaques (most commonly in the carotid or femoral arteries) are now being screened-often incidentally-and reclassified with regard to cardiovascular risk. The distinct morphological traits of vulnerable plaques (such as intraplaque hemorrhage, large lipid-rich necrotic cores, thin fibrous caps, inflammatory activity, and neovascularization) enable their detection and characterization with noninvasive ultrasound methods. Recent technological advances have facilitated the detailed assessment of plaque morphological features (particularly in the carotid arteries) and thus have identified markers of vulnerability or rapid progression. Here we review the recent literature on the noninvasive ultrasound assessment of atherosclerotic plaques, from anatomical foundations to recent advances. The review covers established morphological descriptors, emerging approaches (such as three-dimensional ultrasound, contrast-enhanced ultrasound, noninvasive vascular elastography, and microvascular flow imaging), current limitations, and future avenues for better cardiovascular risk stratification.