UC San Diego

ObjectiveTo evaluate quantitative ultrashort echo time (UTE) magnetic resonance imaging (MRI) biomarkers, pore-to-matrix ratio (PMR), and matrix index (MI) for assessing trabecular bone in the proximal femur across aging and osteoporosis-related bone status.Materials and methodsIn this prospective study, 92 female subjects (20–83 years) were classified into four groups based on age and DXA-derived T-scores: Young Normal (n = 19), Old Normal (n = 14), Osteopenia (n = 44), and Osteoporosis (n = 15). All participants underwent 3-T hip MRI using 3D dual-echo proton-density-weighted UTE (PD-UTE) and short TR adiabatic inversion recovery UTE (STAIR-UTE) sequences. Measurements were performed in the femoral head and neck by two readers. Interobserver agreement was assessed via intraclass correlation coefficients (ICC). Group differences were analyzed with the Kruskal–Wallis test and Holm-adjusted post hoc tests. Spearman correlation analysis and receiver operating characteristic (ROC) analysis were performed.ResultsPMR increased and MI decreased with worsening bone status. Significant differences were observed between Young Normal and all older groups (p < 0.001). PMR from the oblique-coronal total femoral head differentiated Old Normal from Osteoporosis (5.35 vs. 8.10; p < 0.05). Both PMR (ρ = −0.406 to −0.211) and MI (ρ = 0.333–0.402) significantly correlated with T-scores (all p < 0.05). The areas under the ROC curve were 0.776 (95% CI, 0.584–0.909) for PMR and 0.738 (95% CI, 0.548–0.886) for MI. Interobserver reproducibility was substantial to almost perfect (ICC: 0.73–0.99).ConclusionPMR and MI demonstrated measurable differences across age and bone status and may provide complementary information on trabecular bone characteristics.Key PointsQuestionCan ultrashort echo time (UTE) MRI biomarkers address the need for radiation-free assessment of age- and osteoporosis-related trabecular bone changes in the proximal femur?FindingsPore-to-matrix ratio (PMR) increased and matrix index (MI) decreased with aging and worsening bone status, and femoral head PMR differentiated osteoporosis from normal bone.Clinical relevanceUTE-MRI-derived PMR and MI may provide radiation-free, complementary information to dual-energy X-ray absorptiometry for assessing trabecular bone changes associated with aging and osteoporosis.Graphical Abstract