Ultra-high field MRI: parallel-transmit arrays and RF pulse design

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Radiofrequency (RF) Engineering

Background:

• Ultra-high field (UHF) MRI (7 tesla and above) offers advanced imaging but faces challenges with RF field non-uniformity and power deposition.
• Parallel transmission (pTx) has emerged as a key technology to address these UHF MRI limitations since the early 2000s.

Purpose of the Study:

• To provide a comprehensive review of parallel transmission (pTx) in magnetic resonance imaging (MRI).
• To discuss the application, challenges, and future prospects of pTx technology, particularly at ultra-high fields (UHF).

Main Methods:

• Survey of dedicated RF coils used for pTx.
• Discussion of electromagnetic (EM) field simulations for modeling coil behavior.
• Analysis of safety considerations, including specific absorption rate (SAR) management.
• Description of RF pulse design methods and practical application guides.

Main Results:

• pTx effectively combats RF inhomogeneity and accelerates spatially selective RF pulses at UHF MRI.
• Modeling and simulation are crucial for understanding and optimizing pTx coil performance.
• Safety protocols, particularly SAR management, are essential considerations for pTx implementation.

Conclusions:

• Parallel transmission (pTx) is a vital technique for overcoming RF challenges in UHF MRI.
• Further development and validation are needed for the routine clinical adoption of pTx.
• pTx holds significant promise for advancing MRI capabilities and applications.