Hexagonal gradient scheme with RF spoiling improves spoiling performance for high-flip-angle fast gradient echo...

Area of Science:

• Magnetic Resonance Imaging
• Signal Processing

Background:

• Unwanted signal in Magnetic Resonance Imaging (MRI) can degrade image quality, particularly at high flip angles.
• Traditional constant spoiling gradients may not sufficiently suppress these artifacts.

Purpose of the Study:

• To introduce a new framework using time-varying gradients combined with RF spoiling to minimize unwanted MRI signals.
• To evaluate the efficacy of this novel technique, termed hexagonal spoiling, in reducing signal artifacts.

Main Methods:

• A hexagonal spoiling scheme was developed, where spoiler gradients cycle through hexagonal vertices, compatible with RF spoiling.
• The hexagonal spoiling method was compared against constant spoiling gradients.
• Extended Phase Graph (EPG) simulations, phantom studies, and in vivo imaging were employed for assessment.

Main Results:

• Hexagonal spoiling markedly reduced unwanted signal in both transient and steady states across simulations and experiments.
• In vivo, for adipose tissue at 1.5 Tesla and a 60° flip angle, steady-state unwanted signal decreased from 22% with constant spoiling to 2% with hexagonal spoiling.

Conclusions:

• Hexagonal spoiling, a time-varying gradient scheme, effectively enhances signal spoiling in MRI when used with RF spoiling.
• This method provides superior performance over traditional constant spoiling gradients, leading to cleaner images.