Comparison of a Novel MRI Technique that Produces Equivalent Bone Contrast with 2D-CT for the Assessment of Glenoid Bone Loss

Background: Advanced imaging in patients with shoulder instability can be variable. MRI offers visualization of soft tissue injuries including capsulolabral injuries, however may not be ideal to assess osseous injuries. CT examination may often be desired as the accepted standard for assessment of glenoid and humeral bone loss, the extent of which can dictate surgical management in the adolescent age group in which bone loss is common. Hypothesis/Purpose: Our hypothesis, MRI bone sequence/method (FRACTURE: FFE Resembling A CT Using Restricted Echo-spacing) can provide measurements comparable to standard CT for glenoid bone loss. The objective of this study was to validate this technique in a cadaveric glenoid bone loss model using 2D-CT as the reference standard. Methods: Glenoid fractures of varying sizes were arthroscopically created in 10 cadaveric shoulders. 2D-CT and MRI FRACTURE on 3T Philips Ingenia; Philips Healthcare, Best, Netherlands) were performed on all 10 shoulders. FRACTURE is a 3D-gradient echo pulse sequence with restricted echo-spacing combined with an automated post-processing is a technical innovation which provides superior cortical and trabecular bone contrast on MRI. The CT and MRI were presented in a blinded fashion to 2 experienced musculoskeletal radiologists for independent measurement of the glenoid fracture length, width, as well as % glenoid bone loss using the best-fit circle method. Paired t-tests were performed to compare the measurements obtained on CT with those obtained on the MR FRACTURE images. Intraclass correlation coefficient was used to measure interobserver reliability. Results: There was no statistically significant difference between CT and MRI in terms of the measured glenoid fracture length(P-value=0.54) or fracture width(P-value=0.86). The mean length measured on CT was 23.40 mm ± 6.87 and on MRI was 22.96 mm ± 7.38. The mean width on CT measured 7.96 mm ± 3.51 and on MRI measured 7.89 mm ± 3.18. There was also no statistically significant difference between CT and MRI in terms of measured glenoid bone loss (P-value=0.65). Intraclass correlation coefficients for interobserver reliability ranged from 0.95 to 0.99 for measurements performed on CT and MRI. Conclusion: Measurements of glenoid fracture and associated % bone loss on CT were comparable with measurements obtained using the MR FRACTURE technique. Inter-observer reproducibility for these measurements was excellent. MRI FRACTURE technique may obviate preoperative CT in patients with anterior shoulder instability.