title: Magnetic resonance imaging is comparable to computed tomography for determination of glenoid version but does not accurately distinguish between Walch B2 and C classifications.
abstract: BACKGROUND
  Computed tomography (CT) scan is the standard for the preoperative assessment of glenoid version and morphology before total shoulder arthroplasty. However, the capacity of magnetic resonance imaging (MRI) to visualize bone morphology has improved with advancing technology. The purpose of this study was to compare the accuracy of MRI to CT for assessment of glenoid version and Walch classification.
  
  
  METHODS
  Three fellowship-trained shoulder surgeons assessed glenoid version and Walch classification of 30 patients with primary shoulder osteoarthritis who received both CT and MRI scans before total shoulder arthroplasty. Version measurements, Walch classification, and observer agreement were compared.
  
  
  RESULTS
  Mean glenoid version was -15.5° and -18.6° by CT and MRI, respectively (P = .17). Interobserver reliability coefficients were good for both imaging modalities (CT, 0.73; MRI, 0.62). Intraobserver coefficients were good to excellent for CT (range, 0.76-0.87) and good for MRI (range, 0.75-0.79). For Walch classification, interobserver reliability for both modalities was merely fair, whereas intraobserver reliability was moderate to good. Although identification of type A1, A2, and B1 was nearly identical between CT and MRI, there was observer disagreement on type B2 (P = .001) and C glenoids (P = .03). Specifically, MRI underidentified type B2 and overidentified type C compared with CT.
  
  
  CONCLUSIONS
  MRI is largely comparable to CT scan for evaluation of the glenoid, with similar measurements of version and identification of less extreme Walch glenoids. However, MRI is less accurate at distinguishing between type B2 and C glenoids.
authors.affiliation: Boston Sports and Shoulder Center, Waltham, MA, USA; New England Baptist Hospital, Boston, MA, USA.
authors.forename: Jeremiah T
authors.initials: JT
authors.lastname: Lowe
authors.affiliation: Tufts University School of Medicine, Boston, MA, USA.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Testa
authors.affiliation: Boston University School of Medicine, Boston, MA, USA.
authors.forename: Xinning
authors.initials: X
authors.lastname: Li
authors.affiliation: Boston Sports and Shoulder Center, Waltham, MA, USA; New England Baptist Hospital, Boston, MA, USA.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Miller
authors.affiliation: Beth Israel Deaconess Medical Center, Boston, MA, USA.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: DeAngelis
authors.affiliation: Boston Sports and Shoulder Center, Waltham, MA, USA; New England Baptist Hospital, Boston, MA, USA; Tufts University School of Medicine, Boston, MA, USA. Electronic address: ajawa@nebh.org.
authors.forename: Andrew
authors.initials: A
authors.lastname: Jawa
mesh_terms: D000072228:Arthroplasty, Replacement, Shoulder; D061165:Glenoid Cavity / Q000000981:diagnostic imaging*; D006801:Humans; D008279:Magnetic Resonance Imaging; D015588:Observer Variation; D010003:Osteoarthritis / Q000000981:diagnostic imaging* / Q000601:surgery; D015203:Reproducibility of Results; D012785:Shoulder Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed / Q000379:methods
keywords: Osteoarthritis; Walch classification; arthroplasty; computed tomography; glenoid version; magnetic resonance imaging