MR imaging of the rotator cuff tendon: interobserver agreement and analysis of interpretive errors.

PURPOSE

To evaluate accuracy in interpretation of shoulder magnetic resonance (MR) images and interobserver agreement and to characterize the types of errors.

MATERIALS AND METHODS

Five radiologists with varying experience independently and retrospectively twice interpreted the MR images of 222 symptomatic patients who underwent both MR imaging and shoulder arthroscopy. The first interpretation was a blind review; the second was with knowledge of the arthroscopic findings.

RESULTS

For full-thickness tears, the sensitivity, specificity, and accuracy were 84%-96%, 94%-98%, and 92%-97%, respectively, and for partial tears, 35%-44%, 85%-97%, and 77%-87%, respectively. There was no statistically significant difference between readers in the detection of partial or full-thickness tears. There was a statistically significant difference between readers in the no-tear category. Cohen kappa values generally indicated improved interobserver agreement proportional to the readers' experience (full-thickness tears, 0.731-0.881; partial tears, 0.168-0.443).

CONCLUSION

Diagnosis of a full-thickness tear can be learned to a high degree of accuracy. Despite the radiologist's level of experience and knowledge of the arthroscopic findings, the sensitivity for diagnosis of partial tears is poor.