Pulse wave propagation through a stenotic artery with plaque constituents of different stiffnesses: In vitro-experiment and fluid–structure interaction simulation

Abstract

Vulnerable (typically, softer) carotid plaques may rupture leading to blockages downstream in the brain with high potential for ischemic stroke. Pulse Wave Imaging (PWI) developed by our group is an ultrasound-based technique for pulse wave visualization and pulse wave velocity (PWV) mapping. In this study, the accuracy of PWV estimation in stenotic vessels was assessed in simulation and phantom studies. Fluid–structure interaction simulations were performed in a stenotic (50%) vessel. Experimental stenotic (50%) polyvinyl alcohol (PVA) phantoms (2 mm thickness, 8 mm lumen diameter, and 165 mm length) with soft/medium/hard plaque constituents of different stiffness (E0 = 12 kPa, 30 kPa, 94 kPa) were constructed matching the simulation geometry and parameters. Pulse waves were generated by a computer-controlled pump using a physiologic flow waveform. The RF frames were acquired by a Verasonics Vantage 256 system using a 5 MHz (L7-4) linear array. The acquired RF frames were beamformed using a delay and sum algorithm, and a GPU-based, 1-D cross correlation method was used to estimate the wall velocities. The acceleration peak of the pulse wave was tracked to estimate PWV. PWVs of 2.6 ms−1, 3.4 ms−1, and 4.5 ms−1 were, respectively, measured for the soft, medium, and stiff plaque material in experimental phantoms. The PWV of 2.7 m/s was confirmed for the medium plaque in simulation. This fundamental study demonstrated, thus, a good accuracy by PWI in the estimation of plaque PWV and its underlying stiffness for future stroke risk assessment.