Background: Osteoporosis is commonly evaluated using dual-energy X-ray absorptiometry (DXA) for bone mineral density (BMD). Non-contrast computed tomography (CT) scans provide an alternative for opportunistic osteoporosis assessment. This study aimed to evaluate screening thresholds for osteoporosis based on CT attenuation values in Hounsfield units (HU) of L1–L4 vertebrae from CT scans of the abdominal region, compared to DXA assessments of the lumbar spine and hips. Methods: Conducted retrospectively over approximately two years, the analysis included 109 patients who had both CT and DXA scans within 12 months, excluding those with metal artifacts affecting the vertebrae. CT attenuation values in the trabecular region of the vertebrae were measured and compared among three groups based on the lowest T-score from DXA. Results: In a predominantly female cohort (mean age 66.3 years), the lowest CT attenuation values for L1–L4 vertebrae showed a moderate correlation with the lowest T-score, with a Pearson correlation coefficient of 0.542 (95% CI: 0.388, 0.667). A HU threshold of ≤142 at the L1 vertebra showed 91.9% sensitivity and 48.4% specificity, while a threshold of ≤160 HU showed 97.3% sensitivity and 31.3% specificity for screening osteoporosis. Conclusions: This study supports the use of non-contrast CT with these HU thresholds as an opportunistic tool for osteoporosis assessment.

Osteoporosis is commonly evaluated using dual-energy X-ray absorptiometry (DXA) for bone mineral density (BMD). Non-contrast computed tomography (CT) scans provide an alternative for opportunistic osteoporosis assessment. This study aimed to evaluate screening thresholds for osteoporosis based on CT attenuation values in Hounsfield units (HU) of L1-L4 vertebrae from abdominal CT scans, compared to DXA assessments of the lumbar spine and hips. Conducted retrospectively over about two years, the analysis included 109 patients who had both CT and DXA scans within 12 months, excluding those with metal artifacts affecting the vertebrae. CT attenuation values in the trabecular region of the vertebrae were measured and compared among three groups based on the lowest T-score from DXA. In a predominantly female cohort (mean age 66.3 years), significant correlations were found between the CT HU values of L1-L4 vertebrae and the lowest T-score. CT HU values differed significantly among normal (17.4%), low bone mass (46.8%), and osteoporosis (35.8%) groups (P < 0.001). A HU threshold of ≤142 at the L1 vertebra showed 91.9% sensitivity and 48.4% specificity, while a threshold of ≤160 HU showed 97.3% sensitivity and 31.3% specificity for screening osteoporosis. In conclusion, this study supports the utility of non-contrast CT with these HU thresholds as an opportunistic osteoporosis assessment.

Background: This study aimed to determine the prevalence of DXA-detected lumbar scoliosis in postmenopausal women based on dual-energy X-ray absorptiometry (DXA) scans and identify associated risk factors. Methods: A total of 261 postmenopausal women aged ≥50 years who underwent lumbar spine DXA before June 2021 were included. Lumbar scoliosis was defined as a Cobb angle ≥ 10° measured from DXA images. Logistic regression analysis was performed to evaluate associated risk factors. Diagnostic performance of DXA-based Cobb angle measurements was assessed in the radiographic validation subgroup using radiography as the reference standard. Results: The prevalence of DXA-detected lumbar scoliosis was 14.9% (39/261; 95% CI, 10.8–19.9%). Increasing age was significantly associated with scoliosis, while body mass index, bone mineral density, and T-scores at the lumbar spine, hip, and femoral neck were not. DXA and radiographic Cobb angle measurements demonstrated strong agreement (ICC = 0.91, 95% CI 0.73–0.96), with a mean difference of −2.63°. Diagnostic accuracy was 82.1%, with sensitivity 62.1%, specificity 97.4%, PPV 94.7%, and NPV 77.0%. ROC analysis demonstrated good discriminative performance (AUC = 0.88, 95% CI, 0.79–0.98); an exploratory cutoff of 6.5° yielded the highest Youden index. Conclusions: DXA-detected lumbar scoliosis was identified in 14.9% of postmenopausal women undergoing DXA. DXA-based Cobb angle measurements demonstrated strong agreement with radiographic assessment and may facilitate opportunistic case detection of likely lumbar scoliosis during routine BMD assessment.