Abstract
We evaluate the accuracy of a semi-automated software package for annotating landmark points on vertebral body outlines in dual-energy X-ray absorptiometry (DXA) images of adults. The aim of the study was to determine the accuracy with which a non-expert radiographer could use the software to annotate vertebrae in support of osteoporotic vertebral fracture diagnosis and grading. In this study, 71 GE Lunar iDXA vertebral fracture assessment (VFA) images were used. Annotations of landmark points on vertebral body outlines were performed by four observers. Annotations consisted of 33 points on each vertebra between T4 and L4 inclusive; 11 on the upper end-plate, 8 on the anterior side, 11 on the lower end-plate, and 3 on the pedicle (429 points for each image). There were a total of 19 (26%) cases in which the non-expert radiographer made vertebral level assignment errors. All of them were one level too high (with L1 identified as T12). Their median error for landmark annotation was 1.05 mm, comparable to the 0.8 mm error achieved by the expert radiographers. Normative mean vertebral body heights vary between approximately 22 mm at T4 and 36 mm at L4 in females. Mild, moderate, and severe vertebral fragility fractures are defined through vertebral body height reductions of 20%, 25%, and 40%, respectively. Therefore, the annotation accuracy of the software when used by a non-expert was 14-23% of the height reduction indicative of a mild fracture. We conclude that, even when used by non-experts, the software can annotate vertebral body outlines accurately enough to support vertebral fragility fracture diagnosis and grading.