Purpose To investigate the diagnostic performance of virtual calcium imaging (VCI) parameters from photon-counting detector (PCD) CT for assessing lumbar vertebral osteoporosis. Materials and Methods A phantom study was first conducted using standard- and low-dose PCD CT to assess the stability and reproducibility of VCI parameters. Participants who underwent dual-energy x-ray absorptiometry (DXA), the reference standard for osteoporosis assessment, and standard- or low-dose PCD CT were prospectively enrolled. Partial correlation coefficients were used to assess associations between VCI parameters and DXA-derived T-scores. Measurements were obtained from anterior, middle, and posterior vertebral subregions. Diagnostic performance for osteoporosis was evaluated using receiver operating characteristic analysis. Results In the phantom study, VCI parameters from standard- and low-dose PCD CT showed strong positive correlations with known bone density (r = 0.94-0.95; P r = 0.64, 0.67, and 0.62, respectively; all P P 3 or less, and ME70 of 112.43 HU or less, receiver operating characteristic analysis demonstrated good diagnostic performance for osteoporosis (areas under the receiver operating characteristic curve, 0.90, 0.91, and 0.89, respectively), with sensitivities of 85%, 87%, and 82% and specificities of 83%, 79%, and 84%, respectively. Similar results were observed in the standard-dose group. Conclusion VCI parameters from PCD CT showed strong correlations with DXA T-scores and demonstrated high diagnostic performance for osteoporosis, suggesting a promising opportunistic screening tool for lumbar vertebral bone density assessment. Keywords: CT Photon Counting, CT Dual Energy, Thorax, Spine Supplemental material is available for this article. © RSNA, 2026.
Chen et al. (Wed,) studied this question.