Accelerated motion-robust abdominal 3D T1ρ mapping using diamond radial sampling.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Quantitative Imaging
• Biomedical Engineering

Background:

• Abdominal 3D T1ρ mapping is crucial for characterizing tissue properties but is often limited by long scan times and motion artifacts.
• Existing methods require breath-holding or respiratory gating, which can be challenging for patients and may still be affected by motion.
• Developing faster, motion-robust techniques is essential for routine clinical application of abdominal quantitative MRI.

Purpose of the Study:

• To develop and validate a novel, accelerated, motion-robust, free-breathing abdominal 3D T1ρ mapping technique.
• To combine variable-density diamond radial k-space sampling with fast Magnetization-Prepared Angle-Modulated Partitioned-k-space Spoiled Gradient-Echo Snapshots (fast-MAPSS).
• To assess the accuracy and feasibility of this new method compared to standard techniques.

Main Methods:

• 3D MAPSS T1ρ imaging was performed at 3T in phantoms and nine healthy volunteers.
• Cartesian sampling (reference) was compared with stack-of-stars and diamond radial sampling.
• T1ρ values were calculated using mono-exponential fitting with MAPSS and fast-MAPSS, comparing different spin-lock times and sampling strategies.

Main Results:

• Diamond radial sampling achieved a 2.2-fold acceleration compared to stack-of-stars.
• Phantom experiments showed minimal T1ρ differences (<2%) between diamond sampling and reference Cartesian MAPSS.
• Volunteer scans demonstrated strong correlations (R² ≥ 0.88) between sampling methods and T1ρ quantification techniques, with minimal bias (<1.5 ms).

Conclusions:

• Fast-MAPSS combined with diamond radial k-space sampling provides a clinically feasible, motion-robust 3D T1ρ mapping method for the abdomen.
• This technique significantly reduces scan time while maintaining quantification accuracy comparable to standard MAPSS methods.
• The developed approach holds promise for improved abdominal quantitative MRI in free-breathing conditions.