Feasibility of bone-like MRI for acetabular morphology assessment in developmental dysplasia of the hip

OBJECTIVES: To evaluate the clinical utility of "multi-echo recombined gradient echo" (MERGE)-based bone-like MRI for delineating acetabular osseous morphology in developmental dysplasia of the hip (DDH), and to determine whether this technique provides quantitative measurements with agreement to CT. MATERIALS AND METHODS: This retrospective study included 32 patients with DDH (2 men, 30 women; aged 33 ± 13 years, mean ± standard deviation) who underwent both hip MRI and CT between August 2020 and September 2023. One clinically affected hip per patient was analyzed. The MRI protocol included T1-weighted imaging, short tau inversion-recovery (STIR), and a MERGE sequence with a negative look-up table to enhance bone-like contrast. Joint space width (JSW) and center-edge (CE) angles were measured on all modalities. RESULTS: Mean JSW was 4.2 ± 1.4 mm (T1-weighted), 3.0 ± 1.3 mm (STIR), 3.3 ± 0.9 mm (MERGE), and 3.4 ± 1.1 mm (CT), without a significant difference between MERGE and CT (p = 0.776). Mean CE angles were 29.7 ± 9.5°, 30.9 ± 9.9°, 31.4 ± 10.1°, and 31.4 ± 10.1°, respectively, without significant difference between MERGE and CT (p = 0.908). CONCLUSION: As an exploratory feasibility study, our findings suggest that MERGE-based bone-like MRI may allow reliable visualization of acetabular morphology and provide quantitative measurements with good agreement to CT. The ability to simultaneously evaluate osseous and soft-tissue structures supports its potential as a radiation-free and comprehensive imaging method for DDH, warranting further validation in larger cohorts. RELEVANCE STATEMENT: MERGE-based bone-like MRI enables simultaneous visualization of the hip bone and soft tissues without radiation exposure. This method provides a clinically feasible, MRI-based alternative to CT for evaluating acetabular morphology in DDH. KEY POINTS: MERGE-based MR bone-like imaging visualized acetabular morphology and provided CE angle and joint space measurements comparable to CT. MERGE showed the closest agreement with CT for CE angle and joint space, outperforming T1WI and STIR in accuracy. This technique offers radiation-free, comprehensive hip evaluation, serving as a potential MRI-based alternative to CT in DDH assessment.