[Bone scintigraphy in metastases]

The three fold interest of bone scintiscanning is discussed in relation to 182 cases of bone metastases of various origins. Firstly, this technic facilitates early diagnosis of invasion of the bone by the detection of metastatic lesions which, in 7.7% of cases are still infraradiologic, or even of reflex algodystrophy of the legs, which can be detected only from a scintiscan, long before X-ray plates can show the lumbar metastasis which is responsible. Secondly, the method is able to pick up more metastatic sites in 54.4% of cases than can be detected by X-ray; this is confirmed by investigation of the S/R ratio (ratio of the number of strongly binding sites to the number of sites showing radiologic damage) which is greater than unity for a considerable period. Thirdly, repeated scintiscanography provides a prognosis, because the survival time appears to be fairly closely correlated with the regression, stability or extension of strongly binding sites, although a "flare phenomenon" may give the erroneous impression that the metastatic process has deteriorated. Repeated scintiscanography also provides a good way of evaluating the efficacy of medical treatment, particularly in the case of bone metastases of mammary or prostatic origin. Sometimes, the decision for or against prophylactic or palliative orthopedic surgery may be based to a considerable extent on data provided by scintiscan.