[Densitometry in suspected preclinical osteoporosis: quantitative computerized tomography versus dual energy roentgen absorptiometry].
The bone mineral density of 85 patients with suspicion of a preclinical osteoporosis was measured at the lumbar spine by using quantitative computed tomography (QCT) in single-energy technique (SEQCT) and dual-energy technique (DEQCT) as well as by using dual-energy X-ray absorptiometry (DEXA). Additionally, the bone density of 63 of these patients was measured at the left femoral neck using DEXA. DEQCT und DEXA of the lumbar spine showed only a moderate correlation (R = 0.75) and differed considerably concerning the classification of the patients as normals or individuals with a mineral deficit when compared with age-matched normals (relative mineral deficit). The DEXA proved to be susceptible to degenerative alterations of the lumbar spine. Because of the extremely low dose of radiation and the good reproducibility the DEXA could nevertheless be recommended as a method for the long-time progress control especially for younger patients. SEQCT and DEQCT showed a very strong correlation (R = 0.98). The SEQCT with its lower dose of radiation should be sufficient for a long-time progress control and in many cases also for the initial diagnostics. Significant but only moderate correlations were found between the bone density at the femoral neck and the DEXA or DEQCT results (R = 0.68 respectively R = 0.63) for the lumbar spine, so that the linear regression did not render any useable approximations. Sufficiently exact information about the mineralization status of a certain skeletal site can only be obtained by direct measurement.