Intramural shear strain can highlight the presence of atherosclerosis: A clinical in vivo study

Intramural Shear Strain (ISS), the angular deformation of the arterial tissues within the depth of the wall, can be assessed by estimating the wall longitudinal motion at different depth. This study investigates the association between risk factors of early-stage atherosclerosis (age and diabetes) with the longitudinal motion of the wall, compared to classical markers such as radial distensibility and intima-media thickness, in carotid ultrasound B-mode sequences. Our previously developed Contour and Speckle Tracking (CST) method is applied in vivo to estimate the wall 2D trajectory and calculate motion and stiffness parameters. A novel method to evaluate the ISS is then introduced and applied. Fourteen young volunteers, 14 older volunteers and 14 older diabetic patients were involved in this study. Results show a significant difference in the longitudinal displacement index between both healthy groups and the older patients (p<;0.0001 and p<;0.005 for the young and the older, respectively), while interestingly no significant difference was found between the 2 elder groups in the cross-sectional distensibility. The longitudinal motion within the depth of the wall followed a characteristic pattern, with a very sharp decrease of amplitude traducing a high ISS (Θ ~ 1 radian) for both healthy populations, whereas it remained lower and quasi-linear for the disease group.