MR-GUIDED MR ARTHROGRAPHY OF THE SHOULDER

Purpose: To develop an MR-guided technique for joint puncture in MR ar thrography of the shoulder and to confirm the intracapsular position o f the needle tip by visualization of the flow of contrast media into t he joint. Materials and methods: Three unfixed human shoulder joint sp ecimens were examined on a 1.0 T unit. The optimal point of entrance a nd depth for joint puncture were estimated by means of MR-compatible m arkers on the skin. Needle orientation and localization of the needle tip (MR-compatible 22-gauge needle) in the shoulder joint were monitor ed by rapid localizer gradient-echo sequences in two orthogonal planes . To confirm the intracapsular position of the needle tip, diluted gad olinium-DTPA was administered via a long connecting tube and the flow of contrast media into the joint was viewed directly on an LCD screen using real-time MII imaging (local look technique). Results: The MR-co mpatible markers on the skin allowed determination of the optimal poin t of entrance and estimation of the depth for joint puncture. Passive visualization of the MR-compatible needle due to spin dephasing and si gnal loss provided adequate localization of the intra-articular needle tip position in all specimens, although significant artefacts were pr esent on rapid localizer gradient-echo sequences with an increase in w idth of the apparent needle shaft. Real-time MR imaging of the flow of contrast media was possible using the local look technique and the LC D screen of the MR unit and allowed confirmation of the intracapsular position. Conclusion: MR-guided joint puncture and real-time MR-assist ed contrast media application results in improved MR arthrography and may replace conventional fluoroscopic guidance.