In-vitro validation of 4D flow MRI measurements with an experimental pulsatile flow model

Area of Science:

• Cardiovascular imaging
• Medical physics
• Flow dynamics

Background:

• Phase-contrast magnetic resonance imaging (PCMRI) is crucial for non-invasive cardiovascular assessment.
• Four-dimensional (4D) PCMRI offers volumetric flow data but requires validation in controlled settings.
• Understanding the impact of imaging parameters on 4D PCMRI accuracy is essential for clinical application.

Purpose of the Study:

• To evaluate the precision of 4D PCMRI in quantifying mean flow and peak velocity (Vmax).
• To assess the influence of spatial resolution and velocity encoding sensitivity (Venc) on 4D PCMRI measurements.
• To compare 4D PCMRI results against reference values in a pulsatile flow phantom.

Main Methods:

• A pulsatile flow phantom was integrated into a mock circulatory system.
• 4D PCMRI scans were performed with varying spatial resolutions (minimum 1.5x1.5x1.5mm³) and Venc settings (up to 3x Vmax).
• Mean flow and Vmax derived from 4D PCMRI were compared to phantom flow parameters and 2D PCMRI Vmax.

Main Results:

• 4D PCMRI demonstrated high precision for mean flow (-0.04% to +5.46%) and slightly underestimated Vmax (-1.71% to -3.85%) compared to 2D PCMRI.
• Mean flow accuracy was significantly influenced by spatial resolution, with smaller voxel sizes yielding better results (P<0.001).
• Venc did not affect mean flow measurements, and neither spatial resolution nor Venc impacted Vmax measurement precision.

Conclusions:

• 4D PCMRI accurately measures mean flow and Vmax in a pulsatile flow model.
• Higher spatial resolution enhances the precision of 4D PCMRI mean flow quantification.
• Venc settings up to three times Vmax can be employed without compromising measurement accuracy.