An eight channel transmit system for Transmit SENSE at 3T

The use of high-field MRI has introduced problems with full wave effects. Complex RF transmit pulses show promise as a viable solution to these problems. These RF pulses have driven a need for multi-channel transmit systems that are useable with techniques like Transmit SENSE. We have constructed an eight channel parallel transmit system that meets the requirements to be used for Transmit SENSE. Additionally, the system can be easily integrated with an existing MRI system. A vector modulation system allows all channels to be fully modulated in both phase and amplitude. The output amplifier stage uses a RF current source architecture. When combined with a series resonated coil this provides a significant degree of isolation between array elements. We were able to use an eight channel loop array coil with this system to obtain reasonably independent sensitivity maps. From these it was possible to construct a uniform excitation, and conduct more complex RF pulse design experiments.