title: Glenoid notch MRI findings do not predict normal variants of the anterior and superior labrum.
abstract: OBJECTIVE
  To determine (1) the relationship of a glenoid notch to the presence of a normal labral variant in the anterior-superior glenoid labrum; (2) the inter- and intra-observer reliability of recognising a glenoid notch; and (3) whether magnetic resonance arthrography (MRA) is more reliable than non-contrast magnetic resonance imaging (MRI) in visualising a glenoid notch.
  
  
  METHODS
  From 1995 through 2010, 104 patients underwent MRI or MRA before diagnostic shoulder arthroscopy by the senior author. Five blinded musculoskeletal radiologists independently read the images twice to evaluate for the presence or absence of a glenoid notch. Fifty-nine (57%) patients had normal anterior-superior labral variants. The authors calculated the relationship of the readings to the arthroscopically determined presence or absence of a normal labral variant and the reading's diagnostic performance and rater reliability.
  
  
  RESULTS
  On average, 38% (range 9-65%) of the glenoid scans were read as notched. The sensitivity, specificity, positive predictive value, and negative predictive value of the notch relative to the presence of a normal variant were 43.1%, 71.2%, 70.2%, and 48% versus 44.3%, 77.5%, 79.4%, and 56.1% for MRI and MRA, respectively. The overall average intra-observer κ-values were 0.438 (range 0.203-0.555) and 0.346 (range -0.102 to 0.570) for MRI and MRA, respectively. The average interobserver intra-class correlation coefficient reliability values were 0.730 (range 0.693-0.760) and 0.614 (range 0.566-0.662) for MRI and MRA, respectively.
  
  
  CONCLUSIONS
  A notched glenoid on MRI lacks sufficient diagnostic performance and rater reliability for the clinical detection and prediction of normal anterior-superior labral variants.
authors.affiliation: The Johns Hopkins School of Medicine, The Johns Hopkins University, Baltimore, MD, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Thompson
authors.affiliation: Department of Radiology and Imaging, Weill Medical College of Cornell University, Hospital for Special Surgery, New York, NY, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Carrino
authors.affiliation: Spine Outcomes Center, The Johns Hopkins University, Baltimore, MD, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Skolasky
authors.affiliation: Musculoskeletal Section, Russell H. Morgan Department of Radiology and Radiological Sciences, The Johns Hopkins University, Baltimore, MD, USA.
authors.forename: A
authors.initials: A
authors.lastname: Chhabra
authors.affiliation: Musculoskeletal Section, Russell H. Morgan Department of Radiology and Radiological Sciences, The Johns Hopkins University, Baltimore, MD, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Fayad
authors.affiliation: Musculoskeletal Section, Russell H. Morgan Department of Radiology and Radiological Sciences, The Johns Hopkins University, Baltimore, MD, USA.
authors.forename: A
authors.initials: A
authors.lastname: Machado
authors.affiliation: Musculoskeletal Section, Russell H. Morgan Department of Radiology and Radiological Sciences, The Johns Hopkins University, Baltimore, MD, USA.
authors.forename: T
authors.initials: T
authors.lastname: Soldatos
authors.affiliation: Musculoskeletal Imaging Division, Department of Radiology, Thomas Jefferson University, Philadelphia, PA, USA.
authors.forename: W B
authors.initials: WB
authors.lastname: Morrison
authors.affiliation: Division of Shoulder Surgery, The Department of Orthopaedic Surgery, The Johns Hopkins University, Baltimore, MD, USA. Electronic address: editorialservices@jhmi.edu.
authors.forename: E G
authors.initials: EG
authors.lastname: McFarland
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001175:Arthrography / Q000379:methods*; D003287:Contrast Media; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012785:Shoulder Joint / Q000033:anatomy & histology*; D055815:Young Adult
chemical_list: D003287:Contrast Media