3D ZTE MRI Versus 3D CT for Measurement of Glenoid Bone Loss: An Analysis of Agreement, Accuracy, and Cost Comparison.

Background: Quantifying glenoid bone loss (GBL) in patients with shoulder instability is essential for guiding surgical management and determining the need for bone augmentation procedures. Purpose/Hypothesis: The purpose of this study was to evaluate the diagnostic agreement and cost-effectiveness of 3-dimensional (3D) zero echo time (ZTE) magnetic resonance imaging (MRI) compared with 3D computed tomography (CT) for assessing GBL. It was hypothesized that ZTE MRI would demonstrate strong concordance with CT and serve as a cost-effective, radiation-free alternative. Study Design: Cohort study (Diagnosis); Level of evidence, 2. Methods: Patients undergoing MRI with both 3D ZTE and 2-dimensional proton density fat-saturated (PD FS) sequences, as well as 3D CT of the ipsilateral shoulder, were retrospectively reviewed. Patients with recurrent instability between imaging studies were excluded. GBL was measured independently by 2 raters using the perfect-circle linear method. Interrater and intrarater reliability were assessed using intraclass correlation coefficients (ICCs). Concordance with CT was evaluated using concordance correlation coefficients (CCCs). Cost-effectiveness was preliminarily assessed using institutional imaging charges and diagnostic agreement. Results: Eleven patients were included; 81.8% had ≥3 instability episodes. Mean GBL was 13.2% ± 9.3% (PD FS), 12.8% ± 8.9% (ZTE), and 12.7% ± 8.9% (CT). Inter- and intrarater reliability were excellent (ICC > 0.9). ZTE (CCC, 0.999; 95% CI, 0.997-0.999) and PD FS (CCC, 0.988; 95% CI, 0.974-0.994) demonstrated excellent agreement with CT. Estimated patient-billed costs were $1652 for CT + MRI, versus $1019 for either ZTE MRI or PD FS MRI alone. Corresponding institutional costs were $593 for CT + MRI and $329 for either ZTE or PD FS MRI. Conclusion: 3D ZTE MRI is a reliable and reproducible alternative to CT for quantifying GBL in shoulder instability. With excellent diagnostic agreement, elimination of ionizing radiation, and reduced costs, ZTE MRI may serve as a single-modality solution for preoperative evaluation in select patients.