Receiver Technology

Abstract

Since the introduction of the NMR phased array (Roemer et al., 1990), and the application of accelerated parallel MRI (Pruessmann et al., 1999, Sodickson and Manning, 1997), it has become increasingly clear that the use of a large number of RF coils for signal reception offers substantial increases in SNR and acceleration rates. The optimal number of coils is dependent on application and field strength and might exceed 100 for whole body applications at high field. Because these coil signals have to be received, amplified and digitized independently, the result is an increased complexity of the MRI receiver. At the same time, with the advent of digital radio in the early 1990’s, receiver technology has developed rapidly as well, with increased performance, and reductions in size and cost made possible by improvements in semiconductor technology. Currently, MRI scanners are becoming available with 32 independent channels based on digital receiver technology, and this high number is likely to grow substantially in the near future. In the following we will review some of the issues involved in designing a digital receiver for use with MRI.