The primary trigger for myocardial infarction and stroke is destabilization of atherosclerotic plaques. The chance of a plaque to rupture is related to its composition and geometry. Ultrasound (shear) strain imaging allows assessment of local tissue mechanics and possible risk assessment of vulnerable plaques.

To non-invasively assess the local tissue mechanics of the common carotid artery radiofrequency data were acquired using a linear array ultrasound transducer (Philips 11-3L, f_c=7.5MHz) in longitudinal and in transverse direction. In transverse direction we used multiple beam steered angles. Simultaneously the ECG-signal was recorded. Axial and lateral displacement of the local tissue were estimated using a 2D coarse-to-fine cross-correlation based strain algorithm [1]. And from these displacements we derived the radial strain [2] and the longitudinal shear strain [3].

Both strains showed a cyclic pattern with an increase during the systolic and a decrease during the diastolic phase. The first in vivo results of radial strain in a plaque show increased strain values in the core of the plaque that might be related to a fatty composition.

The first results of non-invasive ultrasound strain imaging using radiofrequency ultrasound demonstrate the potential of quantifying plaque mechanics. Further validation of these methods will open the door for clinical screening of vulnerable plaques.