Wilhelmus Reinerius Maria Mens

Magnetic resonance imaging apparatus comprising an activatable birdcage RF coil

A so-called birdcage coil must be quickly deactivated after having generated an RF magnetic field, so as not to disturb the detection of the generated spin resonance signals by the surface coil (or another coil). To this end, semiconductor switches are included in some of the rod conductors of the birdcage coil. The switches are arranged substantially halfway along the rod conductors, because the RF voltage exhibits a zero crossing at that area. As a result, the semiconductor switches can operate with a low voltage. It has been found that the interruption of the rod conductors which are situated in one symmetry half of the birdcage coil and which carry most current in that half suffices for substantial deactivation.