Complementing Bone Mineral Density Assessment: DXA-Based Radiomics for Vertebral Evaluation in Older Adults

Background and Objectives: Dual-energy X-ray absorptiometry (DXA) provides areal bone mineral density (BMD) and T-scores but does not fully characterize image texture. This study examined the relationship between lumbar T-score and DXA-derived Shannon entropy, a first-order descriptor of image-intensity heterogeneity, and whether entropy differed across densitometric categories in older adults. Materials and Methods: This cross-sectional study included 271 community-dwelling adults aged ≥60 years who underwent lumbar DXA. Regions of interest from L1-L4 were segmented, gray levels were quantized to 8 bits, and entropy was calculated for each evaluable vertebra and averaged at the participant level. Pearson correlation, one-way ANOVA with Tukey post hoc testing, effect sizes, tertile-based discordance analysis, and multiple linear regression were applied. Results: T-score and entropy showed a weak positive correlation (r = 0.203; R² = 0.04; p < 0.001). Entropy differed across densitometric categories (F = 9.04; p < 0.001; η² = 0.063). Values were similar in the normal and osteopenic groups (2.151 ± 0.063 vs. 2.150 ± 0.063), whereas the osteoporosis group showed lower entropy (2.111 ± 0.076; p < 0.001). Low entropy was also observed in 27.5% of participants with normal BMD and 29.0% with osteopenia. After adjustment for age, sex, and BMI, T-score was not independently associated with entropy (p = 0.127). Conclusions: DXA-derived Shannon entropy showed limited correspondence with lumbar T-score and lower values in osteoporosis. It should be interpreted as a descriptor of DXA image-intensity heterogeneity, not as a direct measure of trabecular microarchitecture. Further validation is required before clinical application.