Diagnostic and therapeutic impact of MRI and arthrography in the investigation of full-thickness rotator cuff tears

Investigation of shoulder pain is important before surgical treatment. The presence or absence of a full-thickness rotator cuff tear (FTRCT) may deter mine the type of surgical treatment. Both MRI and conventional arthrography can be used, but little is known about their relative diagnostic and thera peutic impact. We performed a prospective trial assessing: (a) the influenc e of MRI and arthrography results on the clinician's diagnostic thinking (d iagnostic impact); (b) the influence of the results on the clinician's ther apeutic thinking (therapeutic impact); and (c) the diagnostic performance o f the two techniques in patients with surgical confirmation. A total of 104 consecutive patients with shoulder problems referred to a specialist ortho paedic shoulder clinic underwent pre-operative investigation with MRI and a rthrography. The surgeon's diagnosis, diagnostic confidence and planned tre atment were measured before the investigation, and then again after the res ults of each investigation. Before the presentation of the investigation re sults, the patients were randomised into two groups. In one group MRT was p resented first; in the other group, arthrography. The MRI results led to fe wer changes in diagnostic category (14 of 46, 30 %) than arthrography (20 o f 54, 37 %), but the difference was not significant (P > 0.5). Magnetic res onance imaging led to slightly more changes in planned management (17 of 47 , 36 %) than arthrography (14 of 55, 25 %), but again the difference was no t statistically significant (P > 0.3). The results of the second investigat ion always had less diagnostic and therapeutic impact than the first. The a ccuracy of MRI for : FTRCT in 38 patients with surgical confirmation was 79 %, sensitivity 81% and specificity 78 %; the accuracy of arthrography was 82 %, sensitivity 50 % and specificity 96 %. The clinical diagnosis and man agement plan can be adequately defined by a single radiological investigati on. Magnetic resonance imaging and arthrography had fairly similar diagnost ic and therapeutic impact and comparable accuracy, although MRI; was more s ensitive and less specific. Magnetic resonance imaging may be the preferred investigation because of its better demonstration of soft tissue anatomy.