US Velocimetry in Participants with Aortoiliac Occlusive Disease

TL;DR

This study evaluates the feasibility of using high-frame-rate contrast-enhanced ultrasound and particle image velocimetry to quantify blood flow in patients with aortoiliac stenosis, highlighting both potential and current limitations.

Contribution

It demonstrates the clinical feasibility of US velocimetry for blood flow measurement in aortoiliac disease using HFR-CEUS and PIV analysis, identifying key challenges for future implementation.

Findings

Flow quantification achieved in 41 of 42 locations

Flow disturbances associated with high flow complexity and vorticity

Challenges include loss of correlation, shadow regions, and contrast issues

Abstract

The accurate quantification of blood flow in aortoiliac arteries is challenging but clinically relevant because local flow patterns can influence atherosclerotic disease. To investigate the feasibility and clinical application of two-dimensional blood flow quantification using high-frame-rate contrast-enhanced US (HFR-CEUS) and particle image velocimetry (PIV), or US velocimetry, in participants with aortoiliac stenosis. In this prospective study, participants with a recently diagnosed aortoiliac stenosis underwent HFR-CEUS measurements of the pre- and poststenotic vessel segments. Two-dimensional quantification of blood flow was achieved by performing PIV analysis, which was based on pairwise cross-correlation of the HFR-CEUS images. Visual inspection of the entire data set was performed by five observers to evaluate the ability of the technique to enable adequate visualization of blood flow. The contrast-to-background ratio and average vector correlation were calculated. In two participants who showed flow disturbances, the flow complexity and vorticity were calculated. Results: 35 participants were included. Visual scoring showed that flow quantification was achieved in 41 of 42 locations. In 25 locations, one or multiple issues occurred that limited optimal flow quantification, including loss of correlation during systole, shadow regions, a short vessel segment in the image plane, and loss of contrast during diastole. In the remaining 16 locations, optimal quantification was achieved. The contrast-to-background ratio was higher during systole than during diastole, whereas the vector correlation was lower. Flow complexity and vorticity were high in regions with disturbed flow. Blood flow quantification with US velocimetry is feasible in patients with an aortoiliac stenosis, but several challenges must be overcome before implementation into clinical practice.