Slice-selective tunable-flip adiabatic low peak-power excitation pulse

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Radiofrequency (RF) Pulse Design

Background:

• B(1)-inhomogeneity in MRI degrades excitation profile uniformity, especially at higher field strengths.
• Existing gradient modulation techniques for adiabatic excitation often exceed scanner hardware limits.

Purpose of the Study:

• To develop a novel adiabatic pulse for slice-selective excitation that operates within commercial scanner limits.
• To reduce peak radiofrequency (RF) power requirements for adiabatic pulses.

Main Methods:

• Introduced the Slice-selective Tunable-flip AdiaBatic Low peak-power Excitation (STABLE) pulse.
• Employed gradient modulation with a BIR-4-like RF envelope sampled by short spatial subpulses.
• Evaluated pulse performance using simulations, phantom, and in vivo imaging.

Main Results:

• The STABLE pulse demonstrated significantly lower RF peak power requirements.
• Simulations confirmed spatial profile and off-resonance behavior invariance across a range of B(1) values.
• Phantom and in vivo experiments validated adiabaticity and slice selectivity.

Conclusions:

• The STABLE pulse offers a practical solution for B(1)-insensitive, slice-selective adiabatic excitation.
• This pulse design overcomes RF power limitations, enhancing applicability in clinical MRI.
• STABLE pulse technology advances uniform excitation in the presence of RF field inhomogeneity.