Safety of arterial shear wave elastography–ex–vivo assessment of induced strain and strain rates

Abstract

Shear wave elastography (SWE) is a promising technique for characterizing carotid plaques and assessing local arterial stiffness. The mechanical stress to which the tissue is subjected during SWE using acoustic radiation force (ARF), leading to strain at a certain strain rate, is still relatively unknown. Because SWE is increasingly used for arterial applications where the mechanical stress could potentially lead to significant consequences, it is important to understand the risks of SWE- induced strain and strain rate. The aim of this study was to investigate the safety of SWE in terms of induced arterial strain and strain rate ex-vivo and in a human carotid artery in-vivo. SWE was performed on six porcine aortae as a model of the human carotid artery using different combinations of ARF push parameters (push voltage: 60/90 V, aperture width: f/1.0/1.5, push length: 100/150/200 μs) and distance to push position. The largest induced strain and strain rate were 1.46 % and 54 s−1 (90 V, f/1.0, 200 μs), respectively. Moreover, the SWE-induced strains and strain rates increased with increasing push voltage, aperture, push length, and decreasing distance between the region of interest and the push. In the human carotid artery, the SWE-induced maximum strain was 0.06 % and the maximum strain rate was 1.58 s−1, compared with the maximum absolute strain and strain rate of 12.61 % and 5.12 s−1, respectively, induced by blood pressure variations in the cardiac cycle. Our results indicate that ex-vivo arterial SWE does not expose the artery to higher strain rate than normal blood pressure variations, and to strain one order of magnitude higher than normal blood pressure variations, at the push settings and distances from the region of interest used in this study.

Wearable bioadhesive ultrasound shear wave elastography

“…ARFI pushes that generate shear waves for SWE typically require longer pulse durations and higher pressures compared to conventional B-mode ultrasound imaging. Therefore, it is important to consider the biosafety aspects of SWE ( 32 ). In general, the biosafety of SWE should meet the same criteria as conventional B-mode ultrasound imaging.…”

Advances in Noninvasive Carotid Wall Imaging with Ultrasound: A Narrative Review

“…Doherty et al showed increased SWE displacements in regions identified as lipid on MRI, while Huang et al suggested that larger local deformations and increased complexity in deformation patterns are more likely to occur in vulnerable plaques [ 121 , 122 , 123 ]. Using histology as the reference method, Czernuszewicz et al showed increased diagnostic accuracy of elastography when fibrous cap thickness was included in the measurements, with smaller thickness associated with higher rupture risk at a cut-off value of 0.5 mm [ 124 ]…”