Comparison of reliability in two-dimensional computed tomography vs. two-dimensional magnetic resonance imaging for on-track/off-track measurements: analysis of key values for glenohumeral bone loss.

Background: The purpose of the current study was to compare the intraobserver and interobserver reliability in glenoid track measurement using two-dimensional (2D) computed tomography (CT) vs. 2D magnetic resonance imaging (MRI). Our hypothesis was that on-track and off-track assessments using 2D CT and 2D MRI would demonstrate consistent results with good-to-excellent reliability. Methods: Electronic medical records from 2009 to 2019 were reviewed for patients with known shoulder instability and bipolar bone loss. Using 2D CT and 2D MRI, the glenoid and humeral head bone loss was measured to calculate the glenoid track and to assess for on-track and off-track lesions. Results: A total of 24 patients met the inclusion criteria. The overall intraobserver reliability for 2D CT vs. 2D MRI was none to moderate for on-track and off-track assessments (κ = 0.083, 0.25, 0.5). Interobserver reliability for MRI scan was fair for on-track and off-track assessments (κ = 0.299). There was significant correlation between MRI and CT-derived measurements for all included variables ( Conclusion: On-track and off-track assessments using 2D CT and 2D MRI demonstrated inconsistent results; therefore, the additional information provided by 2D CT may be of significant value for clinical decision-making.