Single- versus dual-energy quantitative computed tomography for spinal densitometry in patients with rheumatoid...

Lumbar bone mineral density was measured by both single- and dual-energy quantitative computed tomography in 109 patients with rheumatoid arthritis. The results were corrected for the age-related increase in vertebral fat content by converting them to percentages of expected densities, using sex and energy-level specific regression equations obtained in a normal reference population. The percentages of expected density are approximately 10% lower in the single- than in the dual-energy mode, both in the patients with and without prednisone therapy. This difference is statistically highly significant, and is positively correlated with the duration of the disease and with the degree of radiological joint destruction. The data suggest that the vertebral fat content may be increased in patients with rheumatoid arthritis, as a consequence of disease-dependent mechanisms.