MR-GUIDED JOINT PUNCTURE AND REAL-TIME MR-ASSISTED CONTRAST-MEDIA APPLICATION

Objective: To develop, in MR arthrography of the shoulder joint, an MR -guided technique for localizing the needle puncture and confirming th e intracapsular needle-tip position by visualization of the contrast m edia inflow. Material and Methods: Three unfixed human shoulder specim ens were examined on a 1.0 T MR unit. On the basis of MR-compatible ma rkers, the optimal entrance point for puncturing the joint was determi ned. The precise localization of the needle tip (MR compatible 0.7-mm needle) in the shoulder joint was determined with rapid localizer GRE sequences in 2 orthogonal planes. To confirm the intracapsular positio n of the needle tip, diluted Gd-DTPA was applied via a long connecting tube and contrast medium inflow into the joint space was controlled o n an LCD screen in real-time MR imaging (local-look technique). Result s: MR-compatible markers on the skin allowed the rapid determination o f the optimal entrance point for needle puncture. An adequate localiza tion of the intra-articular needle-tip position was possible in all sp ecimens although significant artifacts were present on rapid localizer GRE sequences which resulted in an increase in the apparent width of the needle shaft. Real-time MR imaging of the contrast medium inflow w as made possible by the local-look technique and LCD screen on the MR unit and this allowed confirmation of the intracapsular position. Conc lusion: In MR arthrography of the shoulder, an MR-guided technique in conjunction with the LCD screen and real-time MR imaging would seem to be a practical alternative to conventional fluoroscopic guidance.