title: Posteroinferior labral cleft at direct CT arthrography of the shoulder by using multidetector CT: is this a normal variant?
abstract: OBJECTIVE
  To describe a posterior labral cleft at direct computed tomographic (CT) arthrography of the shoulder by using multidetector CT and to compare this finding with a true posterior labral tear.
  
  
  METHODS
  Institutional ethics review board approval was obtained, and informed consent was waived. One hundred twenty-seven shoulders in 126 patients were examined with direct CT arthrography by using 16- or 64-section multidetector CT and arthroscopy. Two musculoskeletal radiologists retrospectively reviewed CT arthrographic images for the presence, location, and size of a posterior labral tear, defined as a detectable contrast material-filled focal discontinuity of the labrum on an axial image, proved by using arthroscopy. A posterior labral cleft was defined as a false-positive lesion at CT arthrography that was proved to be a normal finding arthroscopically. Sensitivity, specificity, accuracy, positive and negative predictive values of tears and clefts were determined; incidence according to the patient's age and sex and the laterality (right or left shoulder), location, and size of the lesion were compared.
  
  
  RESULTS
  In 127 shoulders, radiologists 1 and 2 found 12 and 11 posterior labral tears, respectively, seen exclusively in male patients with posterior instability. Radiologist 1 observed 24 (18.9%) clefts, and radiologist 2 observed 20 (15.7%) clefts, seen more commonly in female patients (P = .037 for radiologist 1, P = .026 for radiologist 2) and in the inferior quadrant of the posterior labrum (along 7- to 8-o'clock positions, P < .05 for both radiologists); these clefts were shallower than labral tears (P = .005 for radiologist 1, P = .025 for radiologist 2).
  
  
  CONCLUSIONS
  At direct CT arthrography, a labral cleft may be a normal variation of the posterior labrum.
authors.affiliation: Department of Radiology, Seoul National University Bundang Hospital, 300 Gumi-dong, Bundang-gu, Seongnam-si, Gyeonggi-do 463-707, Korea.
authors.forename: Guen Young
authors.initials: GY
authors.lastname: Lee
authors.forename: Jung-Ah
authors.initials: JA
authors.lastname: Choi
authors.forename: Joo Han
authors.initials: JH
authors.lastname: Oh
authors.forename: Ja-Young
authors.initials: JY
authors.lastname: Choi
authors.forename: Sung Hwan
authors.initials: SH
authors.lastname: Hong
authors.forename: Heung Sik
authors.initials: HS
authors.lastname: Kang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001175:Arthrography / Q000379:methods*; D016009:Chi-Square Distribution; D003287:Contrast Media; D005260:Female; D006801:Humans; D007483:Iothalamic Acid / Q000031:analogs & derivatives; D007593:Joint Instability / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012737:Sex Factors; D000070599:Shoulder Injuries; D012785:Shoulder Joint / Q000000981:diagnostic imaging*; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D007483:Iothalamic Acid; C002587:ioxitalamic acid