A birdcage coil (16) used in conjunction with a magnetic resonance imaging
apparatus includes a first conductive loop (81, 581), a second conductive
loop (82, 582), and a plurality of first conductor rungs (80, 580)
disposed between the first and second conductive loops. A third conductor
(83, 83'', 583) is coupled to the second conductive loop at resonance
frequencies, such as by second conductor rungs (84, 84'', 584). The
birdcage coil also includes switches (590) for switching the birdcage
coil at least among: 1) an RF transmit mode to operate as an RF transmit
coil; and 2) an RF receive mode to operate as an RF receive coil.