Safety of Shear Wave Elastography as Evidenced From Carotid Artery Strain and Strain Rate Induced by Acoustic Radiation Force Impulse and Arterial Pulsations

ObjectiveThe aim of this study was to investigate the mechanical effects of carotid shear wave elastography (SWE) in vivo as its effects on the arterial wall have not been thoroughly examined.MethodsWe evaluated the mechanical effects of carotid SWE in vivo in terms of the radial strain and strain rate to which acoustic radiation force impulses (ARFIs) expose the arterial wall, and compared them with the strain and strain rate induced by arterial pulsation in 13 healthy study subjects (seven individuals 20–35 y of age and six individuals 50–65 y of age). Additionally, we explored whether mechanical effects vary with timing of ARFI and subject age.ResultsThe young cohort was found to have, compared with the old cohort, a higher diastolic ARFI-induced peak strain (p = 0.002) and peak strain rate (p = 0.001), and a lower diastolic ARFI-induced peak negative strain rate (p = 0.013). When comparing cardiac phases, diastolic ARFIs were found to induce a lower peak negative strain rate than systolic ARFIs (p = 0.006). Importantly, ARFI-induced peak strain was lower than that caused by arterial pulsation in both age cohorts (p < 0.0001). The ARFI-induced peak strain rate was slightly higher than that caused by arterial pulsation at rest but lower than published exercise data. The ARFI-induced peak negative strain rate was similar to that caused by arterial pulsation.ConclusionOur results indicate that arterial SWE does not expose the arterial wall to any higher strain or strain rate than is experienced during normal arterial pulsation. Further research is required to validate the results in arteries containing vulnerable plaques.