[Nuclear medicine diagnosis and therapy in urology. Diagnosis of bone metastases].
Bone scintigraphy with 99mtechnetium-labelled polyphosphonates is the most sensitive test for early detection of skeletal metastases. Bone metastases are a major factor in prognosis and have a considerable influence on the therapy selected. In patients with prostate cancer, we recommend routine bone scintigraphy in the initial staging. Follow-up bone scans are indicated whenever a patient develops pain, an elevated level of acid phosphatase, or a rise in prostate specific antigen (PSA). Routine bone scans are not necessary for the initial staging of patients with renal cell carcinomas, bladder carcinomas and testicular tumours. Scans should be routinely performed, however, in patients with bone pain or elevated alkaline phosphatase or when radiological findings are inconclusive. Bone scanning is necessary in patients with neuroblastoma, both for the initial diagnosis and during follow-up in all cases with known skeletal involvement. In addition, bone scintigraphy should be performed in cases of recurrent or suspected malignant phaeochromocytoma as a complement to scintigraphy with iodine-123- or iodine-131-MIBG, respectively. Even though skeletal scintigraphy is a very sensitive test, it lacks specificity. This can be compensated, however, by careful interpretation of the scan in the light of the patient's history and the clinical findings. As a positive side-effect, bone scanning--especially in the form of multiphase scintigraphy--may detect renal abnormalities, concurrent diseases or complications in the upper or lower urinary tract. If scintigraphic findings are doubtful, plain film radiographs are required or, in selected cases, bone biopsy must be performed.