Premium
Eight‐channel parallel transmit‐receive system for 7 T MRI with optically controlled and monitored on‐coil current‐mode RF amplifiers
Author(s) -
Gudino Natalia,
Zwart Jacco A.,
Duyn Jeff H.
Publication year - 2020
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.28392
Subject(s) - amplifier , electromagnetic coil , radio frequency , current (fluid) , channel (broadcasting) , mode (computer interface) , nuclear magnetic resonance , physics , materials science , telecommunications , optoelectronics , electrical engineering , computer science , engineering , cmos , operating system
Purpose To demonstrate a practical implementation of an eight‐channel parallel‐transmit system for brain imaging at 7 T based on on‐coil amplifier technology. Methods An eight‐channel parallel transmit‐receive system was built with optimized on‐coil switch‐mode current RF power amplifiers. The amplifiers were optically controlled from an eight‐channel interface that was connected to a 7 T MRI scanner. The interface also optically received a down‐converted version of the coil current sensed in each amplifier for monitoring and feedback adjustments. Results Each on‐coil amplifier delivered more than 100 W peak power and provided enough amplifier decoupling (<−15 dB) for the implemented eight‐channel array configuration. Phantom and human images were acquired to demonstrate practical operation of this new technology in a 7 T MRI scanner. Conclusion Further development and improvement of previously demonstrated on‐coil technology led to successful implementation of an eight‐channel parallel‐transmit system able to deliver strong B 1 fields for typical brain imaging applications. This is an important step forward toward implementation of on‐coil RF amplification for high‐field MRI.