Some observations of the design of rf coils for human internal use

Some features of the design and implementation of NMR probes for insertion into peripheral orifices of the body are described. In particular, the possibilities of using parasitic coils without direct connections in conjunction with conventional whole body coils are examined. The use of windings around the NMR probe carrying gradient pulses as a means of eliminating the very high signals from tissue immediately adjacent to the coil windings is also evaluated. These approaches are, in practice, difficult to combine, and hence need to be viewed almost as alternative possibilities. Practical results of experimental investigations are presented using both phantoms and volunteers.