Pre-amplifiers for a 15-Tesla magnetic resonance imager

Abstract

High-field magnetic resonance imagers (MRI) give better signal-to-noise ratio (SNR) and image contrast. However clinical MRIs are currently limited to 3 Tesla (T) magnetic field strength. To create an uncommon 15 T scanner for research use, we evaluated several low-cost, intended for wireless communication, GaAs enhancement-mode pseudomorphic high electron mobility transistors (ePHEMT) in the critical preamplifier slot. This paper reports the experimental results that were obtained at both module and system levels. When evaluated in our prototype 15 T scanner front-end's preamplifier slot, the candidate devices' sub 1dB noise figures enabled image SNR - 110 in a water phantom (test object) with a standard pulse sequence. Crisp and artifact-free images could be obtained with these candidate devices. In conclusion, high performance pre-amplifiers for 15 T MRIs can be realized using low cost ePHEMTs originally marketed for wireless communications.