Background: Osteoporosis is a prevalent metabolic bone disorder characterised by reduced bone mass and deterioration of bone microarchitecture. Dual-energy X-ray absorptiometry (DEXA) is the gold standard for BMD evaluation, but its accuracy is compromised in degenerative spine due to artefacts such as osteophytes and aortic calcifications. Computed tomography (CT)-based Hounsfield Unit (HU) measurements and magnetic resonance imaging (MRI)-derived Vertebral Bone Quality (VBQ) scores have emerged as potential surrogate markers for BMD.

Objective: To compare MRI VBQ scores and CT HU values with DEXA T-scores and evaluate their diagnostic utility in assessing osteoporosis and osteopenia in patients with degenerative spine pathology.

Methods: This retrospective observational study included patients who underwent lumbar spine MRI, CT, and DEXA scans within a three-month interval. VBQ scores were calculated from T1-weighted sagittal MRI images using vertebral and cerebrospinal fluid signal intensities. CT HU values were measured from L1 to L4 vertebrae in axial, sagittal, and coronal planes. DEXA T-scores of the spine and femur were used as reference standards. Statistical analyses included Pearson correlation, ANOVA, and ROC curve analysis.

Results: The study cohort comprised 104 patients who underwent lumbar spine MRI, CT, and DEXA scans. The mean age was 59.9 ± 11.9 years, with a slight female predominance (male: female ratio of 46:58). VBQ scores showed strong negative correlations with DEXA T-scores (r = −0.727 for spine, −0.783 for femur). CT HU values demonstrated strong positive correlations with DEXA T-score (r = 0.745 for spine, 0.680 for femur). Cutoff values for diagnosing osteopenia were ≥2.2 for VBQ and ≤163 HU for CT. Cutoff values for diagnosing osteoporosis were ≥2.6 for VBQ and ≤105 HU for CT. VBQ and HU values also showed a very strong inverse correlation (r = −0.869). Among 25 patients with osteoporotic vertebral compression fractures (OVCF), DEXA misclassified 8 patients as normal or osteopenic. In contrast, VBQ and HU correctly identified 23 and 21 patients, respectively, as osteoporotic.

Conclusion: VBQ and CT HU values are reliable surrogate markers for BMD assessment in the degenerative spine. These modalities offer practical alternatives to DEXA, particularly when DEXA is unavailable or confounded, and can enhance opportunistic screening and preoperative planning.