Measurement of lumbar vertebral body attenuation at PET-CT is a reliable method of diagnosing osteoporosis

Aim

This study investigates the potential of positron emission tomography-computed tomography (PET-CT) as a reliable tool for the diagnosis of osteoporosis, using attenuation values as a marker for bone mineral density (BMD) assessment.

Materials and Methods

We retrospectively identified 305 patients who underwent both PET-CT and dual-energy X-ray absorptiometry (DEXA) within a six-month interval at a tertiary healthcare centre. Attenuation values were measured from the first lumbar vertebra (L1) on noncontrast CT images acquired during PET-CT scans. These values were then compared with corresponding DEXA T-scores to determine their diagnostic performance. Statistical analyses, including one-way Analysis of Variance (ANOVA), Pearson correlation, and receiver operating characteristic (ROC) curve analysis were employed to assess the correlation between PET-CT attenuation values and DEXA-defined osteoporosis.

Results

The mean Hounsfield units (HU) differed significantly between groups classified by DEXA as osteoporosis, osteopenia, or normal BMD (P < 0.001). A strong correlation was found between HU and DEXA T-scores (Pearson coefficient = 0.65). Using logistic regression, we identified HU thresholds of 120 for 90% sensitivity and 98 for 90% specificity. The optimal balanced threshold was 109 HU, achieving both 80% sensitivity and specificity. The ROC curve for the model showed an area under the curve (AUC) of 0.88, indicating high diagnostic accuracy.

Conclusion

PET-CT can effectively screen for osteoporosis, offering a noninvasive, opportunistic diagnostic tool that requires no additional radiation exposure or resources. This study establishes 109 HU as the optimal threshold for diagnosing osteoporosis on PET-CT, providing a significant opportunity for early intervention and improved patient care.