Comparison of rates of change in bone density as measured by dual-energy X-ray absorptiometry and quantitative computed tomography in osteoporotic females treated with fluoride

We conducted a retrospective comparison of the rates of change in vertebral bone density measured by two densitometric techniques: dual-energy X-ray a bsorptiometry (DXA) and quantitative computed tomography (QCT) In osteoporo tic women treated with fluoride. To compare both densitometric methods, lum bar vertebral bone density was determined before and during fluoride therap y in 104 osteoporotic women. All patients signed an informed consent under a protocol approved by our University Institutional Review Board. All subje cts had at least three serial measurements using both densitometric techniq ues over the studied time period. Linear regression was used to calculate r ate of change values for each patient. In agreement with previous published reports, lumbar density increased linearly over time both with DXA and QCT . Rates of change determined by DXA and QCT were significantly correlated ( r = 0.88, p < 0.0001) and this relationship was independent of the magnitud e of the increase in density. Either densitometric technique may be used to evaluate the axial skeletal response to fluoride therapy.