[The use of bone density measurements in the diagnosis and therapy of osteoporosis].
Bone firmness and risk of fracture depend on factors like bone density, bone structure, elasticity of bone materiel and many others. Bone density is an important single factor which has moreover the advantage of being measureable rather precisely today. Unfortunately, the individual values of bone density scatter very much, i.e. the range of normal values is very large so that bone density values alone do not allow a very fine graduation of osteoporosis. At least as important as bone density is its change in the course of time. Three procedures which complete each other partially are primarily at our disposal today for the determination of bone density. The double energy X-ray absorption (DXA) is a plain procedure for the examination of the lumbar spine and/or the femoral neck. The resulting content of bone minerals comprises both cortical and trabecular bone and can be influenced by superimposed tissue. The exposure to irradiation by DXA is small, however the pictures are not of diagnostic quality and supplementary X-rays are recommended in order to avoid erroneous interpretations. In favorable cases a reproducibility of 1% can be achieved. At least 5% change are however necessary in the osteoporotic patient in order to be recognized with certainty. In quantitative computerised tomography (QCT) we distinguish between procedures for the examination of trabecular bone density in vertebral bodies (axial OCT) and procedures for the separate determination of trabecular and cortical bone density in the extremities (pQCT). Axial QCT is also used for the examination of the lumbar spine. Its reproducibility is comparable with that of DXA, the sensitivity of QCT is however higher than that of DXA.(ABSTRACT TRUNCATED AT 250 WORDS)
Rüegsegger
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Institut für biomedizinische Technik der Uni.
D015502:Absorptiometry, Photon; D015519:Bone Density; D001842:Bone and Bones / Q000000981:diagnostic imaging; D006801:Humans; D010024:Osteoporosis / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed
Einsatz der Knochendichtemessung in der Diagnostik und der Therapie der Osteoporose.