Focused navigation for respiratory-motion-corrected free-running radial 4D flow MRI

Area of Science:

• Cardiovascular Imaging
• Medical Physics
• Magnetic Resonance Imaging

Background:

• Respiratory motion significantly degrades the quality of 4D flow MRI data.
• Accurate quantification of blood flow and vessel dimensions is crucial for diagnosing cardiovascular diseases.
• Existing motion correction techniques may have limitations in free-running acquisitions.

Purpose of the Study:

• To validate the focused navigation (fNAV) technique for correcting respiratory motion in free-running radial whole-heart 4D flow MRI.
• To assess the accuracy of fNAV-corrected 4D flow measurements against ground truth and other methods.

Main Methods:

• Respiratory motion signals were derived from radial readouts using fNAV and converted into displacement coefficients for motion correction.
• Simulated 4D flow datasets with non-rigid respiratory motion were used for in vitro validation.
• In vivo validation was performed in 25 patients, comparing fNAV 4D flow with 2D flow, navigator-gated Cartesian 4D flow, and uncorrected 4D flow.

Main Results:

• fNAV demonstrated accurate displacement coefficient estimation in simulated data.
• fNAV-corrected 4D flow measurements showed significantly smaller differences from ground truth compared to uncorrected data for vessel area, net volume, and peak flow.
• In vivo, fNAV 4D flow measurements correlated strongly with 2D flow and navigator-gated 4D flow, outperforming uncorrected 4D flow.

Conclusions:

• Focused navigation (fNAV) is a validated method for correcting respiratory motion in free-running radial 4D flow MRI.
• fNAV-corrected 4D flow provides accurate and reliable measurements comparable to established techniques.
• This technique offers significant improvements over uncorrected 4D flow data, enhancing diagnostic capabilities.