Diagnostic Performance of Vertebral Fracture Assessment by the Lunar iDXA Scanner Compared to Conventional Radiography

The purpose of this study was to evaluate the diagnostic performance of vertebral fracture assessment (VFA) using the Lunar iDXA scanner. Conventional spinal radiographs and images acquired by dual-energy X-ray absorptiometry (DXA) of 350 subjects (269 females, 81 males) were evaluated by two different readers. We visualized 4,476/4,550 (98.4 %) vertebrae from T4 to L4 on VFA images compared to 4,535/4,550 (99.7 %) on radiographs. Among the visualized vertebrae, 205/4,535 (4.5 %) and 190/4,476 (4.2 %) were identified as nonfracture deformities by reading of radiographs and VFA, respectively. Vertebral fractures (VFs) were 231 in 126 patients and 228 in 125 patients by semiquantitative assessment of radiographs (SQ-Rx) and by VFA, respectively. There was excellent agreement between the two techniques and high diagnostic performance of VFA both on a per-vertebra basis (k score = 0.984, 95 % CI 0.972–0.996, sensitivity 98.68 %, specificity 99.91 %, PPV 98.25 %, NPV 99.93 %) and on a per-patient basis (k score = 0.957, 95 % CI 0.925–0.988, sensitivity 96.83 %, specificity 98.66 %, PPV 97.60 %, NPV 98.22 %). In older patients (≥65 years) affected by moderate or severe osteoarthritis, SQ-Rx and VFA identified 96 VFs and 95 versus 90 vertebral deformities, respectively. This study demonstrates that most vertebrae are evaluable using the iDXA scanner, with improved VFA diagnostic performance even in discriminating mild VFs from vertebral deformities. Therefore, VFA may be appropriate as an alternative to conventional radiography in patients at high risk of VF who are undergoing DXA bone densitometry and in the follow-up of osteoporotic patients on treatment.