Free-Breathing Fat Quantification Using a Phase Error-Corrected Cartesian Acquisition With Spiral Profile Ordering

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Medical Physics
• Radiology

Background:

• Proton density fat fraction (PDFF) mapping is crucial for assessing liver and pancreatic diseases.
• Existing MRI techniques often require breath-holding, limiting patient comfort and scan efficiency.
• High-resolution, free-breathing abdominal PDFF mapping remains a challenge.

Purpose of the Study:

• To develop and validate a phase-corrected, time-interleaved multi-echo gradient echo Cartesian acquisition with spiral profile ordering (TIMGRECASPR) for abdominal PDFF mapping.
• To demonstrate the technique's flexibility and self-gating capabilities at high isotropic resolutions (3T).
• To assess the accuracy and homogeneity of PDFF quantification in the liver and pancreas.

Main Methods:

• Developed a methodological framework to correct phase errors from eddy currents and concomitant gradients in TIMGRECASPR.
• Optimized sequence parameters using XCAT simulations and validated in phantoms and in vivo.
• Compared liver and pancreatic PDFF, T2*, and homogeneity against a clinical Cartesian breath-hold technique in five healthy volunteers.

Main Results:

• Phase corrections successfully mitigated peripheral PDFF bias, particularly at higher resolutions.
• Liver PDFF maps showed improved homogeneity with accurate quantification (0.6% bias, 0.11% wSD).
• Pancreatic boundaries were clearly visualized, yielding accurate PDFF maps (1.1% bias, 0.37% wSD).

Conclusions:

• The developed free-breathing TIMGRECASPR sequence is feasible for abdominal PDFF mapping at 3T.
• Accounting for phase errors is essential for accurate, high-resolution PDFF quantification.
• The technique offers sampling flexibility and inherent self-gating capabilities.