Validation of oblique line contrast (W-index) for osteoporosis risk screening in panoramic radiographs using peripheral dual-energy X-ray absorptiometry.

The objective of this study was to validate the usefulness of the W-index (WI) for screening patients at risk of osteoporosis by correlating the WI results with those obtained from peripheral dual-energy X-ray absorptiometry (pDXA). The W-index is based on oblique line contrast on panoramic radiographs, in which the pixel intensity of the oblique line is compared with the pixel intensity of adjacent structures at the mandibular ramus. A total of 333 patients with panoramic radiographs and pDXA results were evaluated according to T-score results and WI measurements. A Spearman correlation test was executed to assess the correlation between measures. Patients were divided into 3 groups: normal bone mineral density (BMD), osteopenia, or osteoporosis. The WI values were compared with the Kruskal-Wallis test. A significant but negligible correlation was found between the pDXA and WI results for all peripheral sites assessed. Statistically significant differences in the WI results emerged between patients with normal BMD and osteoporosis (P = 0.007) as well as between those with osteopenia and osteoporosis (P = 0.010). There were no significant differences in WI between patients with normal BMD and osteopenia (P = 0.598). The results of the study indicate that WI values can differentiate patients with normal BMD or osteopenia from patients with osteoporosis, suggesting that the WI is an easy, convenient tool to screen patients for low BMD using panoramic radiographs.