Diagnostic accuracy of DXA compared to conventional spine radiographs for the detection of vertebral fractures in children

Objectives In children, radiography is performed to diagnose vertebral fractures and dual energy x-ray absorptiometry (DXA) to assess bone density. In adults, DXA assesses both. We aimed to establish whether DXA can replace spine radiographs in assessment of paediatric vertebral fractures.

Methods Prospectively, lateral spine radiographs and lateral spine DXA of 250 children performed on the same day were independently scored by three radiologists using the simplified algorithm based qualitative technique and blinded to results of the other modality. Consensus radiograph read and second read of 100 random images were performed. Diagnostic accuracy, inter/intraobserver and intermodality agreements, patient/carer experience and radiation dose were assessed.

Results Average sensitivity and specificity (95% confidence interval) in diagnosing one or more vertebral fractures requiring treatment was 70% (58%-82%) and 97% (94%- 100%) respectively for DXA and 74% (55%-93%) and 96% (95%-98%) for radiographs. Fleiss’ kappa for interobserver and average kappa for intraobserver reliability were 0.371 and 0.631 respectively for DXA and 0.418 and 0.621 for radiographs. Average effective dose was 41.9µSv for DXA and 232.7µSv for radiographs. Image quality was similar.

Conclusion Given comparable image quality and non-inferior diagnostic accuracy, lateral spine DXA should replace conventional radiographs for assessment of vertebral fractures in children.