Eight-channel parallel transmit-receive system for 7 T MRI with optically controlled and monitored on-coil...

Area of Science:

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

Background:

• High-field MRI (7 Tesla and above) offers enhanced signal-to-noise ratio and spectral resolution for advanced brain imaging.
• Parallel-transmit systems are crucial for improving RF field homogeneity and enabling advanced pulse sequences in high-field MRI.
• On-coil RF power amplification technology aims to overcome limitations associated with RF power delivery and efficiency in MRI systems.

Purpose of the Study:

• To demonstrate a practical implementation of an eight-channel parallel-transmit system for 7 Tesla brain imaging.
• To leverage on-coil amplifier technology for improved RF power delivery and control in a high-field MRI setting.

Main Methods:

• An eight-channel parallel transmit-receive system was constructed using optimized on-coil switch-mode current RF power amplifiers.
• Optical control was implemented for the amplifiers, interfacing with a 7T MRI scanner.
• Coil current sensing with optical feedback was integrated for monitoring and adjustment of amplifier performance.

Main Results:

• Each on-coil amplifier achieved over 100 W peak power output.
• Sufficient amplifier decoupling (<-15 dB) was attained for the eight-channel array configuration.
• Successful phantom and human brain imaging demonstrated the system's practical utility at 7T.

Conclusions:

• The developed eight-channel parallel-transmit system successfully implements on-coil RF amplification technology for 7T brain imaging.
• The system is capable of delivering strong B1 fields, crucial for advanced brain imaging applications.
• This work represents a significant advancement towards the broader implementation of on-coil RF amplification in high-field MRI.