Flow quantification using low-spatial-resolution and low-velocity-resolution velocity images

Area of Science:

• Magnetic Resonance Imaging
• Biomedical Engineering
• Fluid Dynamics

Background:

• Accurate blood flow quantification is crucial in diagnosing vascular diseases.
• Traditional methods often struggle with low spatial/velocity resolution and magnetic field distortions.
• Fourier Velocity Encoding (FVE) offers potential but requires addressing inherent limitations.

Purpose of the Study:

• To develop and validate a robust flow-quantification method using FVE with limited resolution.
• To accurately compensate for Radiofrequency (RF) saturation effects impacting FVE measurements.
• To assess the method's efficacy in phantom studies and in vivo applications like femoral artery flow.

Main Methods:

• Utilized Fourier Velocity Encoding (FVE) with five velocity-encoded images to estimate and correct RF saturation.
• Calculated total flow rate as the first moment of the spin velocity histogram.
• Achieved stationary spin elimination in the flow map, allowing for lower spatial resolution.

Main Results:

• The FVE method demonstrated flow rate measurement errors within +/-10% in phantom studies, even with pixel sizes exceeding vessel dimensions.
• Successfully applied the technique for quantifying blood flow in the femoral artery.
• The method proved effective for analyzing multiple velocity-encoded images.

Conclusions:

• The developed FVE method provides a reliable basis for blood flow analysis, particularly for slow or small vessel quantification.
• Accurate compensation for RF saturation enhances the precision of FVE-based flow measurements.
• This technique offers a valuable tool for non-invasive vascular assessment.