MR grading system of osteochondritis dissecans lesions: comparison with arthroscopy.

OBJECTIVE

To assess the diagnostic performance of combined three-dimensional (3D) gradient-echo (GRE) T1-weighted and routine MR imaging protocol for the evaluation of osteochondritis dissecans (OCD).

MATERIALS AND

METHODS

This prospective study was approved by our institutional review board and all patients gave informed consent. Three-dimensional GRE MR sequence was added to the routine protocol performed on 40 consecutive patients (35 men, 5 women; age range, 12-57 years; mean age, 20 years) with 17 juvenile and 24 adult OCD lesions (27 in knees; 14 in elbows) which were confirmed by arthroscopy. Two independent musculoskeletal radiologists reviewed all MR images. The OCD lesions were classified into five stages by assessing the signal intensity of fragment-bone interface and the integrity of articular cartilage on MR images. Stage-IV and -V lesions were considered as unstable. The sensitivity, specificity, accuracy, and interobserver agreement (κ statistics) were calculated.

RESULTS

The sensitivity, specificity, and accuracy for detection of OCD instability were 100% (11 of 11), 100% (6 of 6), and 100% (17 of 17) in juvenile lesions; and 93% (14 of 15), 100% (9 of 9), and 96% (23 of 24) in adult lesions. The overall accuracy of MR findings in determining the staging was 90% (37 of 41) for reader 1 and 83% (34 of 41) for reader 2. Agreement between readers was substantial with a κ value of 0.75 for MR staging of OCD lesions.

CONCLUSIONS

Three-dimensional GRE T1-weighted MR imaging combined with the routine sequences demonstrates excellent diagnostic capabilities in detecting unstable OCD lesions.