Relationship between 99Tcm-MDP uptake and bone mineral density in patients with prostatic carcinoma

Seventeen men with prostatic carcinoma were investigated with quantitative bone scintigraphy and quantitative computed X-ray tomography before orchiectomy and up to 6 months after this operation. The uptake of 99Tcm-labelled methylene disphosphonate (99Tcm-MDP) and bone mineral density (BMD) were determined for each vertebra from Th10 to L4. Ten patients had normal scintigrams. No change in MDP uptake or BMD was seen after 6 months in these patients. Of the seven patients with abnormal scintigrams, one patient had a clinical sign of progression with an increase in both MDP uptake and BMD. The remaining six patients showed stable or improved clinical status. For their abnormal vertebrae a decrease in MDP uptake was seen, while BMD varied in different ways after 6 months. For the normal vertebrae in these patients with metastatic involvement, no change in MDP uptake was seen. However, the BMD values showed a decrease, indicating a generalized increase in bone resorption at sites distant from the metastases.