Observations on Computerized Quantitative Bone Scintigraphy in Renal Osteodystrophy

Skeletal radiotracer (99mTc-HEDP) uptake was quantitated with and without the aid of a computer in 30 chronic dialysis patients with histologic evidence of renal osteodystrophy. Before scintigraphy, elevated soft-tissue activity due to the absence of renal radiotracer excretion was reduced by hemodialysis. The results were compared with those of a normal group and with the results of the biochemical and the bone morphometric studies of these patients. In all patients the radiotracer uptake was elevated, often markedly. In several patients with minimal histologic bone disease, however, soft-tissue activity could not be normalized by hemodialysis although its influence on the quantitative data could be further reduced (but not excluded) by computer evaluation of skeletal radiotracer uptake. Since the latter technique clearly distinguished the majority of the patients from the normals, it appears that computerized quantitative skeletal analysis is a potentially accurate scintigraphic method for detecting renal osteodystrophy. The significant relationship between skeletal radiotracer uptake, in particular at the bone biopsy site, and only the histologic features of increased bone turnover suggest that hyperparathyroidism is the major cause of this increased tracer uptake in renal osteodystrophy.