Clinical experience with 99mTc-polyphosphate scintigraphy in more than 200 patients with suspected stress fractures is presented. Stress fractures occur in bone which has been weakened as a result of accelerated physiological change induced by excessive muscular and mechanical activity. Unlike traumatic fractures, they are not accompanied by radiographic abnormality early in their course. Bone scintigraphy is sensitive enough to detect the physiological alterations found in stress fractures and was responsible for decreased morbidity in this series of patients due to early diagnosis.

A considerable amount of the nuclear medicine physician's attention is directed toward the screening of patients for tumor diagnosis or for the growth or metastasis of known tumor. Two basic techniques of radionuclide tumor detection are (I) rendering the normal tissue in an organ radioactive and looking for abnormal, nonradioactive areas which represent tumor involvement and (2) making the tumor itself radioactive and hence readily detectable in the relatively nonradioactive normal tissue. Liver, kidney, and thyroid scanning utilize the first method, while metastatic thyroid, brain, and bone tumor scans are examples of the second. The superiority of the technique for finding a hot or bright lesion in a cold or dark background has prompted attempts at extension of this method to the search for tumors. Among the newer agents which specifically label tumors and are being evaluated are Ga6'-citrate in lung carcinomas and lymphomas, Se75-selenite in brain and bone tumors, radioiodinated antifibrinogen for various tumors, and radioiodinated iodoquine in malignant melanoma.