Utility of pre- and post-MR arthrogram imaging of the shoulder: effect on patient care.

OBJECTIVE: MR arthrogram imaging of the shoulder is considered more accurate in assessing shoulder pathology than conventional MRI. Arthrography is a minimally invasive procedure. However, most patients prefer to have conventional MRI rather than MR arthrogram imaging. We report the benefit of assessing pre-arthrogram conventional MRI, to determine whether an MR arthrogram is needed for further evaluation.
METHODS: 100 consecutive conventional shoulder MR and MR arthrography examinations performed on the same patients were reviewed retrospectively by independent reading of 2 musculoskeletal radiologists. Both conventional MR and MR arthrogram examinations were performed on each patient on the same day. Conventional MR and MR arthrogram examinations were assessed for labral tears and supraspinatus tendon tears. All patients went on to arthroscopy.
RESULTS: Of these 100 patients, 43 patients had superior labral anterior to posterior (SLAP) tears, 28 patients had posterior labral tears, 23 patients had anterior labral tears and 47 patients had full-thickness supraspinatus tendon tears on conventional MR examination reading by Reader 1. There were 42 SLAP tears, 26 posterior labral tears, 24 anterior labral tears and 47 full-thickness supraspinatus tendon tears on conventional MR examination read by Reader 2. On MR arthrogram examination, 51 patients had SLAP tears, 33 patients had posterior labral tears, 29 patients had anterior labral tears and 49 patients had full-thickness supraspinatus tendon tears on reading by Reader 1. On MR arthrogram examination, 50 patients had SLAP tears, 31 patients had posterior labral tears, 30 patients had anterior labral tears and 49 patients had full-thickness supraspinatus tendon tears read by Reader 2. MR arthrogram detected eight SLAP tears, five posterior labral tears, six anterior labral tears and two supraspinatus tendon tears not detected on conventional MR examination read by Reader 1. MR arthrogram detected eight SLAP tears, five posterior labral tears, six anterior labral tears and two supraspinatus tendon tears not detected on conventional MR examination read by Reader 2. 18 of the 21 patients with additional finding on MR arthrogram examination had normal appearing conventional MR examinations.
CONCLUSION: Use of pre- and post-MR arthrogram imaging may benefit patient care. When positive findings are demonstrated on MR examination, few additional findings are demonstrated on MR arthrogram examination. These patients may not need to proceed to MR arthrography. If the conventional MR examination is negative, then additional information may be obtained by proceeding to MR arthrography. ADVANCES IN KNOWLEDGE: When positive findings are demonstrated on MR examination, few additional findings are demonstrated on MR arthrogram examination. These patients may not need to proceed to MR arthrography. If the conventional MR examination is negative, then additional information may be obtained by proceeding to MR arthrography.