Native radiologic staging of osteoporosis--CT densitometry of lumbar vertebral spongiosa. A correlation study

Lumbar spine radiographs in 47 patients with manifest or clinically suspected osteoporosis were evaluated, using a staging system, and correlated to quantitative computed tomography (QCT) of lumbar vertebrae. The accuracy of osteoporosis assessment, obtained with plain film analysis, was 60%, the sensitivity 67%, the specificity 56%. Statistical correlation showed high standard deviation of each of the QCT-mean values according to the respective stage groups, and altogether poor linear correlation between increasing morphological stages of osteoporosis and decreasing QCT-values. As our results show plain film differentiation of normal from reduced trabecular bone mineral content is unreliable, even by use of a staging system. The diagnostic value of spine radiographs therefore remains limited to demonstration of advanced osteoporotic changes.