Vertebral computed tomography attenuation to case-find low bone density in people undergoing lung cancer screening

OBJECTIVE: Lung cancer screening (LCS) participants are "high-risk" for osteoporotic fracture. We compared lumbar vertebral Hounsfield-unit CT-attenuation (VHU) from LCS images to standard dual-energy X-ray absorptiometry (DXA), quantitative CT (QCT) and clinical fracture risk tools to identify participants with low bone mineral density (BMD), prevalent vertebral fracture (VF) and incident osteoporotic fracture. METHODS: LCS participants were cross-sectionally analysed at a 2-year follow-up timepoint. BMD was assessed from paired LCS chest low-dose CT (VHU and spine QCT) and DXA scans (T-scores). FRAX and Garvan 10-year fracture risks were calculated from questionnaires. VF were assessed semi-quantitatively from CT scans; 2-year incident VF were identified by comparing baseline and 2-year follow-up LCS CT scans. Participants self-reported 2-year incident osteoporotic fractures. Method discrimination for low DXA-BMD (T-score<-1), prevalent VF and incident fractures were compared. RESULTS: In 91 participants (M: F ratio 0.75), VHU moderately discriminated low DXA-BMD moderately (AUC 0.74), similar to QCT (AUC 0.73), FRAX (AUC 0.82) and Garvan (AUC 0.78)(p > 0.05). VHU performed similarly to DXA spine T-score, QCT, FRAX and Garvan in discrimination for both prevalent VF (AUC 0.71) and incident fractures (AUC 0.71). Correlation and inter-method reliability between VHU and DXA-T-scores were fair (R = 0.42, ĸ < 0.3). CONCLUSION: In LCS, VHU is a convenient alternative to case-find screenees with occult osteoporosis, having comparable discrimination to standard methods for low BMD and osteoporotic fractures. ADVANCES IN KNOWLEDGE: Within-population comparison of osteoporosis assessment methods, shows VHU can comparably 'case-find' LCS participants with occult osteoporotic disease and incident fractures, warranting larger prospective studies.