Carotid plaque assessment using non-invasive shear strain elastography

Stroke is a leading cause of death and morbidity worldwide, and a significant proportion of strokes are caused by carotid atherosclerotic plaque rupture. Non-invasive vascular elastography (NIVE) provides maps of carotid plaque strain computed from radiofrequency ultrasound (US) data sequences. The goal of this project was to evaluate the ability of NIVE shear strain analysis to characterize carotid plaque vulnerability in vivo in patients referred for carotid evaluation. A total of 31 patients with a severe stenosis of the internal carotid artery (> 50%) were enrolled in this study. Twodimensional radiofrequency data were obtained to perform NIVE and to calculate the axial, lateral and shear strains. High-resolution magnetic resonance (MR) images were acquired to segment and quantify the plaques and their internal components. The analysis of plaque regions experiencing large shear strains showed a statistically significant difference (p = 0.046) between symptomatic and asymptomatic patient groups. Statistically significant differences were also found between the time average shear elastogram (Mean |SSE|) of vulnerable versus non-vulnerable plaques without inflammation (p = 0.036). The Mean |SSE| of non-vulnerable plaques with and without inflammation were also significantly different (p = 0.008). The proposed shear measures have the potential to help identifying vulnerable plaques and vulnerable patients.