Efficient 3D FISP-MRF at 0.55 T using long spiral readouts and concomitant field effect mitigation

Area of Science:

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

Background:

• Magnetic Resonance Fingerprinting (MRF) enables quantitative tissue property mapping.
• Fast 3D imaging techniques are essential for reducing scan times.
• Concomitant field effects can degrade MR image quality and precision.

Purpose of the Study:

• To assess the feasibility of SNR-efficient 3D fast imaging with steady state precession MR fingerprinting (FISP-MRF).
• To investigate the use of long spiral readouts for improved SNR in FISP-MRF.
• To mitigate concomitant field effects in 0.55 T FISP-MRF.

Main Methods:

• Implemented 14 FISP-MRF sequences with varying spiral readout lengths (2.9–22.0 ms) using the Pulseq framework.
• Reconstructed datasets using a low-rank, subspace model-based approach with a MaxGIRF spatial encoding model.
• Evaluated concomitant field effects and MRF precision in phantoms and healthy volunteers.

Main Results:

• Simulations showed a ~2x SNR increase in white matter with longer spiral readouts.
• In vivo, MRF T1 and T2 standard deviations in white matter decreased by ~50% after concomitant field mitigation.
• Residual blurring occurred for readouts ≥16.5 ms, defining an optimal operating range (2.9–16.5 ms).

Conclusions:

• Demonstrated SNR-efficient 3D FISP-MRF using long spiral readouts and concomitant field mitigation.
• Achieved improved precision within a defined operating regime (2.9–16.5 ms) after addressing concomitant field effects.