An example of a modular design, showing elements of a PMS dStream system. A head receiver coils has a posterior element, called a Base (visible a bottom part of the head assembly) and exchangeable top elements, either a Head (a), or HeadNeck (b). In the Head configuration the system uses up to 15 receiver channels, in the HeadNeck configuration – up to 20 channels. Images courtesy of Philips Medical Systems.