Abstract Details

Presented By: Zhang, Fuxing
Affiliated with: University of Colorado at Boulder, Mechanical Engineering
Authors: Fuxing Zhang,Craig Lanning,Luciano Mazzaro,Bryan Rech,Jiusheng Chen,S. James Chen,Robin Shandas
From: Department of Mechanical Engineering, University of Colorado, Boulder, CO, 80309, Center for Bioengineering, University of Colorado, Denver, CO, 80045, Division of Cardiology, University of Colorado, Denver, CO, 80045
Title
Blood Velocity and Wall Shear Stress Measurement in a Patient Specific Carotid Bifurcation Model Using the Echo Particle Image Velocimetry Technique: Application and Validation
Abstract

Motivation

Development of a non-invasive, easy-to-use full field opaque flow measurement technique would have significant applications in evaluating details of cardiovascular hemodyamics. Echo Particle Image Velocimetry (Echo PIV), a novel opaque flow velocimetry technique developed in our laboratory, has shown promising results for measuring details of blood flow in simple in vitro models. In this study, we advance the validation to more realistic blood flows using pulsatile, compliant, transparent, patient-specific models.

Methods

A patient-specific carotid bifurcation model was created from silicon 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. Echo PIV spatial resolution was 0.9 (mm) x 0.7 (mm) in lateral and axial directions, and its temporal resolution was 1.4 msec.

Results

Centerline and near wall velocity profiles obtained from Optical PIV and Echo PIV were compared at common branch (CCA), carotid sinus (CS) and internal branch (ICA). Results show that the Echo PIV measurements agreed well with Optical PIV results at each position (mean error = 8.1% +/- 6.3%). Radial velocity profiles from both techniques within the CCA over one cycle show similar patterns. Shear rates from Echo PIV agreed well with those obtained from Optical PIV at all locations as well (mean error = 9.2% +/- 6.7%). Echo PIV was capable of quantitatively recording the complex flow fields observed within the sinus region with both high temporal and high spatial resolution, including recirculation, flow separation, and transient vortices.

Conclusion

Echo PIV provides full-field instantaneous velocity measurements within a physiologically realistic carotid bifurcation vascular anatomy with very good agreement to Optical PIV (discrepancy < 10%) over a wide variety of flow conditions. A clinical study validating this method against MRI phase velocity mapping is currently ongoing.