A radio frequency coil for magnetic resonance imaging or spectroscopy
includes a plurality of generally parallel conductive members (70)
surrounding a region of interest (14). One or more end members (72, 74)
are disposed generally transverse to the plurality of parallel conductive
members. A generally cylindrical radio frequency shield (32) surrounds
the plurality of generally parallel conductive members. Switchable
circuitry (80, 80') selectably has: (i) a first switched configuration
(90, 90') in which the conductive members are operatively connected with
the one or more end members; and (ii) a second switched configuration
(92, 92') in which the conductive members are operatively connected with
the radio frequency shield. The radio frequency coil operates in a
birdcage resonance mode in the first switched configuration and operates
in a TEM resonance mode in the second switched configuration.