Shear Wave Elastography for the Assessment of Carotid Plaque Vulnerability: A Systematic Review

Evidence for the management of asymptomatic carotid stenosis and possibly symptomatic nonstenosing carotid artery disease is limited. In contrary to calcified plaques, soft plaques are considered vulnerable and prone to rupture. Shear wave elastography (SWE), a novel ultrasound technique which uses acoustic wave force to propagate shear wave in tissues, can quantify tissue stiffness through the estimation of Young's modulus (YM) in kPa or shear wave velocity in meter/second. This systematic review is aimed at evaluating the feasibility of SWE in carotid plaque risk stratification in relation to ischemic stroke (PROSPERO registration: ). 18 studies, obtained via search on PubMed, Cochrane, and Embase from inception until November 1, 2022, assessed SWE's feasibility in carotid plaque risk stratification in humans (13 studies) and phantom models (5 studies). Human studies showed heterogeneity with respect to SWE devices, acquisition settings, and methodology, which consequently reflected in the between-study variability of YM values used for distinguishing vulnerable/symptomatic (27-52 kPa) and stable/asymptomatic (28-115 kPa) carotid plaques. However, within-study assessment of all human studies indicated SWE's feasibility in carotid plaque risk stratification. Furthermore, four out of five carotid plaque phantom studies showed the potential of SWE to discriminate tissues of different stiffness comparable to the carotid vessel wall, soft and hard plaques, and with good reproducibility. SWE may potentially offer a bedside risk stratification tool for identifying patients with vulnerable carotid plaques, who may benefit from carotid surgery, stenting, or prolonged dual antiplatelet therapy. Patients with stable carotid plaques could be spared the risks of potentially harmful treatments and complications. However, available data are not enough to facilitate the immediate clinical application of SWE, and therefore, larger prospective clinical are warranted.