PC VIPR: a high-speed 3D phase-contrast method for flow quantification and high-resolution angiography

Area of Science:

• Magnetic Resonance Imaging
• Cardiovascular Imaging
• Flow Quantification

Background:

• Conventional 3D phase-contrast (3DPC) MRI suffers from long scan times, limited coverage, and flow artifacts.
• Measuring flow often requires additional 2D phase-contrast (2DPC) scans, increasing examination complexity.
• These limitations hinder comprehensive volumetric flow assessment and anatomical imaging.

Purpose of the Study:

• To introduce and evaluate isotropic-voxel radial projection imaging (PCVIPR), a highly undersampled 3D radial acquisition technique.
• To assess PCVIPR's ability to improve volumetric coverage and spatial resolution compared to conventional 3DPC.
• To determine the feasibility of retrospective flow rate measurement throughout the imaged volume.

Main Methods:

• PCVIPR utilizes a highly undersampled 3D radial acquisition with reference and three flow-encoded acquisitions per projection.
• Complex difference images were generated, and flow rates were retrospectively calculated from phase-difference information.
• Accuracy was validated in phantoms and volunteers; anatomical images were compared with conventional 3DPC.

Main Results:

• PCVIPR demonstrated high accuracy for flow validation (R2=0.99 in vitro, R2=0.97 in vivo).
• The technique produced minimal artifacts, offering superior resolution and coverage in comparable scan times.
• High acceleration factors were achieved, limited primarily by signal-to-noise ratio.

Conclusions:

• PCVIPR enables rapid acquisition of isotropic, high-resolution angiographic images.
• It allows for retrospective measurement of average flow rates across the entire volume.
• PCVIPR eliminates the need for multiple 2D acquisition planes for flow assessment.