Tumor localization with radionuclides

Neoplasms in the intact patient can be detected either by the uptake of a radiopharmaceutical in the tumor or by the detection of a void created by a new growth within an organ which normally collects the radionuclide. The most familiar example of tumor detection by its own uptake of the radionuclide is in brain scanning. Here, the diffusion of materials such as /sup 99m/Tc pertechnetate into a lesion contrasts with the lack of such diffusion into the surrounding normal brain. The uptake is thought to be due to a breakdown of the blood-brain barrier, although increased vascularity has also been invoked to explain this phenomenon. This uptake is not specific for neoplastic disease as it also occurs in areas of infarction or abscess. The relative sensitivity and specificity of various configurations of uptake in the brain may lead to informed guesses as to the nature of the lesion. Other radiopharmaceuticals that have been used to detect brain lesions include 206Bi-nitrate 111In-chloride, 67Ga citrate and 131In-labeled human serum albumin. The historical development of radionuclides concentrated by tumor is reviewed. (U.S.)