Strain estimation in the carotid artery from ultrasonic wall tracking: A multiphysics model study

Non-invasive assessment of large arteries is important for cardiovascular screening, with the carotid artery being a preferred measurement location. Ultrasonic (US) wall tracking allows measuring arterial motion and distensibility (kinematics), but it is unclear to what extent the technique can be used to derive arterial strain (mechanics). For this purpose, we used a multiphysics model to assess the accuracy of carotid strain estimates derived from a 1D ultrasonic wall tracking algorithm. Distension estimates were then obtained by using tracking points at various depths within the wall, which were further processed to assess radial and circumferential strain. The simulated data demonstrated that circumferential strain can be estimated with reasonable accuracy (especially for the common carotid artery and at the lumen-intima and media-adventitia interface), but the technique does not allow to reliably assess intra-arterial radial strain. These findings were supported by in-vivo data of 10 healthy adults, showing similar circumferential and radial strain profiles throughout the arterial wall. We conclude that these deviations are present due to the complex 3D vessel wall deformation and the presence of specular reflections, with the error depending on the phase in the cardiac cycle and the scanning location.