Fast multistation water/fat imaging at 3T using DREAM-based RF shimming

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Radiofrequency (RF) Physics
• Medical Imaging Technology

Background:

• Whole-body MRI at 3T presents challenges in achieving uniform radiofrequency (RF) excitation.
• B1+ inhomogeneity affects image quality and quantitative accuracy in MRI.
• Dual Refocusing Echo Acquisition Mode (DREAM) offers potential for improved RF field mapping and shimming.

Purpose of the Study:

• To evaluate the effectiveness of DREAM-based B1+ shimming for enhancing image quality in whole-body 3T MRI.
• To demonstrate improvements in RF performance and B1+ homogeneity using DREAM.
• To assess the feasibility of DREAM for water/fat imaging applications.

Main Methods:

• Utilized 3D multistation, dual-echo mDixon gradient echo imaging in 10 healthy subjects.
• Employed station-to-station adapted B1+ shimming based on fast DREAM B1+ mapping on a 3T dual-transmit MRI system.
• Acquired whole-body data using conventional quadrature excitation and DREAM-based B1+ shimmed excitation.

Main Results:

• DREAM-based B1+ shimming significantly improved image quality in multiple body regions (P < 0.02).
• B1+ maps confirmed enhanced B1+ homogeneity and more precise flip angles with DREAM shimming (P < 0.01).
• Rapid dual-channel DREAM B1+ mapping ( < 2 seconds) enables efficient shimming.

Conclusions:

• Station-dependent DREAM-based B1+ shimming effectively improves RF performance and image quality in whole-body MRI.
• DREAM-based shimming is a promising technique for whole-body multistation imaging.
• This method enhances B1+ homogeneity, crucial for high-quality MRI acquisition.