Spatiotemporal phase unwrapping for real-time phase-contrast flow MRI

Area of Science:

• Medical Imaging
• Cardiovascular Imaging
• Magnetic Resonance Imaging

Background:

• Phase-contrast MRI is crucial for quantifying blood flow.
• Real-time imaging presents challenges in phase unwrapping due to undersampling and motion.
• Accurate velocity measurements are vital for diagnosing cardiovascular conditions.

Purpose of the Study:

• To develop and validate a practical phase unwrapping technique for real-time phase-contrast flow MRI.
• To leverage temporal and spatial continuity for robust phase error correction.
• To enable more precise and efficient blood flow quantification in clinical settings.

Main Methods:

• Real-time phase-contrast MRI of through-plane flow using undersampled radial FLASH.
• Phase-sensitive reconstructions with regularized nonlinear inversion.
• Phase unwrapping applied per cardiac cycle, utilizing temporal and spatial continuity for error correction.

Main Results:

• Successful phase unwrapping demonstrated in both phantom and human aorta flow MRI data.
• Halving the velocity encoding resulted in a twofold increase in velocity-to-noise ratio (VNR).
• The method effectively corrected phase inconsistencies in vessel lumen and peripheral regions.

Conclusions:

• The developed phase unwrapping method is effective for real-time flow MRI.
• Measurements can be performed with reduced velocity encoding, leading to improved VNR.
• This technique enhances the diagnostic potential of real-time cardiovascular MRI.