title: MR arthrography in calcific tendinitis of the shoulder: diagnostic performance and pitfalls.
abstract: The purpose was to assess the diagnostic performance of MR arthrography to diagnose calcific tendinitis of the shoulder and to assess the reasons for diagnostic errors. Standard MR arthrograms of 22 patients with calcific tendinitis and 61 controls were retrospectively analyzed by two independent and blinded radiologists. All cases were consecutively collected from a database. Conventional radiographs were available in all cases serving as gold standard. The supraspinatus was involved in 16, the infraspinatus in four and the subscapularis in two patients. All diagnostic errors were analyzed by two additional readers. Reader 1 correctly detected 12 of the 22 shoulders with and 42 of the 61 shoulders without calcific tendinitis (sensitivity 0.55, specificity 0.66). The corresponding values for reader 2 were 13 of 22 and 40 of 61 cases (sensitivity 0.59, specificity 0.69). Inter-rater agreement (kappa-value) was 0.42. Small size of the calcific deposits and isointensity compared to the surrounding tissue were the most important reasons for false negative results. Normal hypointense areas within the supraspinatus tendon substance and attachment were the main reason for false positive results. In conclusion, MR arthrography is insufficient in the diagnosis of calcific tendinitis. Normal hypointense parts of the rotator cuff may mimic calcific deposits and calcifications may not be detected when they are isointense compared to the rotator cuff. Therefore, MR imaging should not be interpreted without corresponding radiographs.
authors.affiliation: Radiology, University Hospital Balgrist, Balgrist, Forchstrasse 340, CH-8008 Zurich, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Zubler
authors.forename: Bernard
authors.initials: B
authors.lastname: Mengiardi
authors.forename: Marius R
authors.initials: MR
authors.lastname: Schmid
authors.forename: Juerg
authors.initials: J
authors.lastname: Hodler
authors.forename: Bernhard
authors.initials: B
authors.lastname: Jost
authors.forename: Christian W A
authors.initials: CW
authors.lastname: Pfirrmann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002114:Calcinosis / Q000175:diagnosis* / Q000000981:diagnostic imaging; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011859:Radiography; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000473:pathology*; D052256:Tendinopathy / Q000175:diagnosis* / Q000000981:diagnostic imaging