Wall Shear Rate Measurement: Validation of a New Method Through Multiphysics Simulations.

Area of Science:

• Cardiovascular fluid dynamics
• Biomedical engineering
• Medical imaging analysis

Background:

• Wall shear stress (WSS) influences endothelial function and atherosclerosis development.
• Wall shear rate (WSR) measurement is challenging in complex geometries like the carotid bifurcation due to flow complexity, wall motion, and noise.
• Existing WSR measurement validation methods are limited by idealistic configurations, lacking realistic physiological conditions.

Purpose of the Study:

• To develop and validate a novel method for accurate wall shear rate (WSR) measurement in the carotid bifurcation.
• To create a gold standard for WSR validation using a fluid-structure interaction model that incorporates realistic physiological factors.
• To assess the feasibility of the proposed WSR measurement technique for in vivo applications.

Main Methods:

• Development of a mathematical model of the carotid bifurcation utilizing fluid-structure simulations to replicate realistic flow, wall movement, and clutter noise.
• Estimation of the near-wall velocity profile using power-law fitting to overcome measurement challenges caused by clutter.
• Validation of the proposed WSR measurement method against the gold standard provided by the simulation model.

Main Results:

• The novel WSR measurement method achieved an accuracy of ±20% under simulated complex flow conditions.
• The mathematical model successfully reproduced realistic flow configurations, wall movement, and clutter noise characteristic of the carotid bifurcation.
• Preliminary in vivo testing on a volunteer demonstrated the feasibility of the WSR measurement technique for clinical application.

Conclusions:

• A novel, validated method for measuring wall shear rate (WSR) in the carotid bifurcation has been established using a realistic mathematical model.
• The developed technique overcomes limitations of previous methods by incorporating fluid-structure interactions and addressing measurement noise.
• The study confirms the potential of this WSR measurement approach for accurate in vivo assessment in cardiovascular research and clinical practice.