Comparative analysis of MRI-based VBQ score and CT-based HU with DEXA-based T-score in assessing BMD in degenerative spine

Study Design: Observational study. Purpose: This study aimed to investigate the diagnostic performance of computed tomography (CT)-derived Hounsfield units (HU) and magnetic resonance imaging (MRI)-based Vertebral Bone Quality (VBQ) scores by comparing them with dual-energy X-ray absorptiometry (DEXA) T-scores in patients with degenerative spine. Overview of Literature: Despine surgery, accurate bone mineral density (BMD) assessment is crucial for surgical planning and postoperative outcomes. DEXA remains the standard method for assessing osteoporosis; however, its accuracy is reduced in degenerative spinal conditions due to artefactual interference. Methods: This study included patients who underwent lumbar spine MRI, CT, and DEXA scans within a 3-month interval. Vertebral and cerebrospinal fluid signal intensities were used to calculate VBQ scores from T1-weighted sagittal MRI. 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 employed as reference standards. Results: In a cohort of 104 patients (mean age, 59.9±11.9 years; 46 males and 58 females), CT HU values exhibited strong positive correlations (r=0.745 spine, 0.680 femur), whereas VBQ scores demonstrated a negative correlation with DEXA T-scores (r=-0.727 spine, -0.783 femur). Optimal thresholds include CT HU values and VBQ scores of ≤163 and ≥2.2 for osteopenia and ≤105 and ≥2.6 for osteoporosis, respectively. CT HU values and VBQ scores were inversely correlated (r=-0.869). Among 25 patients with osteoporotic vertebral compression fractures, DEXA misclassified eight cases, whereas HU and VBQ correctly identified osteoporosis in 21 and 23 patients, respectively. Conclusions: VBQ scores and CT HU values are reliable alternative markers for BMD assessment in the degenerative spine. These modalities provide practical alternatives to DEXA, particularly when DEXA is unavailable or confounded, and can improve opportunistic screening and preoperative planning.