Systematic validation of the echo particle image velocimetry technique using a patient specific carotid bifurcation model

Full field opaque flow measurement technique has significant applications in evaluating details of cardiovascular hemodyamics non-invasively. Echo Particle Image Velocimetry (Echo PIV) is a simple-to-use method that has shown promising results in our previous in vitro studies on measurements of blood flow characteristics. So far, however, no systematic validation of Echo PIV in a realistic vascular anatomy against reference-standard methods has been done. In this paper, a patient-specific carotid bifurcation model was created using biplane angiography data from an adult human male. The model reproduced vascular geometry accurately, while allowing for both Optical PIV and Echo PIV to be performed on the same flow field. A pulsatile pump and a compliance chamber were used to produce physiologically realistic flow conditions with a peak velocity around 70 cm/s, heart rate of 75 beats/min, mean Reynolds number of 1484, and a Womersley number of 16.1. The Echo PIV measurements were validated by Optical PIV technique, a gold standard for velocity field measurement, in terms of velocity, flow rate and wall shear rate profiles at a few different positions in carotid artery. Results show that the Echo PIV measurements agreed well with Optical PIV results, with a mean error 7.7% +/- 3.5% for velocity profiles, and a mean error 9.2% +/- 5.7% for wall shear rate profiles.