Volumetric velocity measurements in restricted geometries using spiral sampling: a phantom study

Area of Science:

• Cardiovascular Imaging
• Magnetic Resonance Imaging
• Fluid Dynamics

Background:

• Accurate velocity quantification in stenotic lesions is crucial for diagnosis.
• Volumetric phase-contrast MRI (PC-MRI) is a key technique for assessing blood flow.
• Spiral readouts offer potential advantages in speed and motion artifact reduction.

Purpose of the Study:

• To assess the accuracy of maximum velocity measurements using volumetric PC-MRI with spiral readouts.
• To compare spiral PC-MRI results with computational fluid dynamics (CFD) and Cartesian MRI.

Main Methods:

• Evaluated maximum velocity, flow, pressure gradient, and streamlines in a stenotic phantom using 1D and 3D volumetric PC-MRI with spiral readouts.
• Compared spiral PC-MRI data to CFD simulations and low-echo-time (TE) Cartesian data.
• Compared flow measurements to 2D through-plane PC MRI.

Main Results:

• Spiral PC-MRI (3D and 4D) demonstrated excellent agreement (<1%) with CFD for maximum velocity.
• Cartesian readouts showed larger deviations (-2.3% and 13%) compared to CFD.
• Spiral PC-MRI sequences slightly overestimated peak pressure drop (13-14%) compared to CFD.

Conclusions:

• Short-TE spiral volumetric PC imaging accurately identifies maximum velocity location and quantifies velocity in stenotic regions.
• This technique shows high accuracy comparable to CFD, outperforming Cartesian readouts.
• Spiral PC-MRI is a promising tool for evaluating hemodynamics in vascular stenosis.