Objective: To assess the diagnostic performance of MR arthrography in the diagnosis of the various types of partial-thickness rotator cuff tears by comparing the MR imaging findings with the arthroscopic findings.
Materials and methods: The series of MR arthrography studies included 202 patients consisting of 100 patients with partial-thickness rotator cuff tears proved by arthroscopy and a control group of 102 patients with arthroscopically intact rotator cuffs, which were reviewed in random order. At arthroscopy, 54 articular-sided, 26 bursal-sided, 20 both articular- and bursal-sided partial-thickness tears were diagnosed. The MR arthrographies were analyzed by two radiologists for articular-sided tears, bursal-sided tears, and both articular- and bursal-sided tears of the rotator cuff. The sensitivity and specificity of each type of partial-thickness tears were determined. Kappa statistics was calculated to determine the inter- and intra-observer agreement of the diagnosis of partial-thickness rotator cuff tears.
Results: The sensitivity and specificity of the various types of rotator cuff tears were 85% and 90%, respectively for articular-sided tears, 62% and 95% for bursal-sided tears, as well as 45% and 99% for both articular- and bursal-sided tears. False-negative assessments were primarily observed in the diagnosis of bursal-sided tears. Conversely, both articular- and bursal-sided tears were overestimated as full-thickness tears. Inter-observer agreement was excellent for the diagnosis of articular-sided tears (k = 0.70), moderate (k = 0.59) for bursal-sided tears, and fair (k = 0.34) for both articular- and bursal-sided tears, respectively. Intra-observer agreement for the interpretation of articular- and bursal-sided tears was excellent and good, respectively, whereas intra-observer agreement for both articular- and bursal-sided tears was moderate.
Conclusion: MR arthrography is a useful diagnostic tool for partial-thickness rotator cuff tears, but has limitations in that it has low sensitivity in bursal- and both articular- and bursal-sided tears. In addition, it shows only fair inter-observer agreement when it comes to predicting both articular- and bursal-sided tears.
Keywords: MR arthrography; Partial-thickness tear; Rotator cuff; Shoulder.