Limitations of quantitative CT in corticosteroid induced osteopenia

Single energy spectrum quantitative CT (SES-QCT) was applied for the assessment of the trabecular bone mineral status in patients under long-term corticosteroid treatment. Seventeen renal graft recipients (RGR) and 12 patients receiving corticosteroid treatment for collagen disease were studied. A reduction of about 40% in the spinal trabecular bone density relative to matched controls was found, associated with the corticosteroid administration. Repeated measurements showed significant reduction in density 4 months after transplantation, and an increase in density after graft rejection. Radiologic or clinical evidence of osteopenia in the spine was not found. Other noninvasive techniques, applied in the upper extremities of the RGR, showed only minor bone reduction compared to controls. The findings of the present study suggest that adipose tissue deposition in the spinal trabeculae can introduce errors in the measurements. Therefore, SES-QCT should not be applied during corticosteroid therapy.