A BIRDCAGE RESONATOR FOR INTRACAVITARY MR-IMAGING

An intracavitary probe for magnetic resonance imaging of the pelvis ha s been developed that takes advantage of the ''inside-out'' spatial ch aracteristics of a birdcage resonator. The probe consists of an eight- leg, birdcage resonator in a low-pass configuration operating in recei ve-only mode. The resonator circuit is mounted on a solid rod, is enca sed in Teflon(R), and has been used to obtain detailed images of pelvi c anatomy in a male canine. The approximate cylindrical symmetry of th e external sensitivity profile of this type of circuit, employed in an intracavitary application, demonstrates the potential superiority of this type of probe design over single-loop intracavitary coils. Axial, coronal, and sagittal MR images, obtained with 8 and 16 cm fields of view, are presented to illustrate the advantages of this type of intra cavitary probe compared with conventional body-coil images. The protot ype described in this report has been designed for clinical use in hum an subjects and is currently undergoing testing to determine its effic acy in the evaluation of rectal, prostate, and gynecologic pathology.