Diagnostic accuracy and therapeutic relevance of CT arthrography and MR arthrography of the shoulder joint

Purpose: In glenohumeral instability, CT arthrography and MR arthrography of the shoulder joint were compared to assess accuracy in diagnosis of labral lesions and other internal derangements of the joint, and to evaluate relevance of both imaging methods for therapy. Methods: 38 patients with symptoms of shoulder instability were examined clinically, arthrographically with CT and MRI, and arthroscopically, Arthrography with CT and MRI was performed in a double-contrast technique after single puncture and simultaneous injection of the contrast agents for both imaging methods. Type and extent of lesions on arthrographic imaging were criteria for planning therapy to a conservative, sole arthroscopic, or open surgical approach. Results: Sensitivity in diagnosis of labral lesion (26 defects) was 85% in CT, 88% in MRI and 100%, if both methods were used. Full-thickness tears of the rotator cuff were visualised in CT in 73%, and in MRI In 100%. Diagnostic accuracy increased from partial to complete to total defects. An open surgical approach was correctly predicted on MRI in 90% and on CT in 71%. A sole arthroscopic therapy was correctly foreseen on both arthrographic techniques in only 38% due to difficulties to assess glenohumeral ligaments. Conclusions: CT arthrography and MR arthrography were excellent for diagnosing labral lesions, MR1 is superior to CT in the imaging of all joint structures. Surgical approach can be accurately predicted with both imaging methods but special surgical techniques cannot be effectively planned to replace diagnostic arthroscopy in all cases.