The quantification of glenoid bone loss in anterior shoulder instability; MR-arthro compared to 3D-CT.
OBJECTIVE
The purpose of this study is to investigate if magnetic resonance imaging with intra-articular contrast (MR-arthro) is as reliable as three-dimensionally reconstructed computed tomography imaging (3D-CT) in quantifying the glenoid bone loss in patients with anterior shoulder instability.


METHODS
Thirty-five patients were included. Sagittal MR-arthro and 3D-CT images of the glenoid surface were obtained pre-operatively. Two observers measured these images twice with OsiriX software in a randomized and blinded way. The intraclass correlations (ICC) of the intra- and inter-observer reliability within one method and an additional Bland-Altman plot for calculating agreement between the two methods were obtained.


RESULTS
The joint estimates of the intra-observer reliability, taking into account the data from both observer A and B, for 3D-CT and MR-arthro were good to excellent. The intra-observer reliability was 0.938 (95% CI: 0.879, 0.968) for 3D-CT and 0.799 (95% CI: 0.639, 0.837) for MR-arthro. The inter-observer reliability between the two observers within one method (3D-CT or MR-arthro) was moderate to good. 3D-CT: 0.724 (95% CI: 0.236, 0.886) and MR-arthro: 0.534 (95% CI: 0.128, 0.762). Comparing both the 3D-CT and MR-arthro method, a Bland-Altman plot showed satisfying differences with the majority of outcomes (89%) within 1 SD.


CONCLUSIONS
Good to excellent intra- and moderate to good inter-observer correlations and a satisfying Bland-Altman plot when compared to 3D-CT show tendencies that MR-arthro is reliable and valid for measuring bony defects of the glenoid.
Department of Orthopedic Surgery, Onze Lieve Vrouwe Gasthuis, Postbox 95500, 1090 HM, Amsterdam, The Netherlands, jemarkenstein@gmail.com.
Jeroen E
JE
Markenstein
Kjell C C J
KC
Jaspars
Victor P M
VP
van der Hulst
W Jaap
WJ
Willems
D000293:Adolescent; D000328:Adult; D005260:Female; D061165:Glenoid Cavity / Q000000981:diagnostic imaging* / Q000473:pathology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007593:Joint Instability / Q000150:complications / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010014:Osteolysis / Q000175:diagnosis* / Q000209:etiology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult