Diagnosis of cerebral metastases by thallium 201

We have studied the diagnostic potential of thallium 201 in cerebral metastases. Twenty-five patients with one or several metastases have been investigated with two tracers, 201T1 and sodium pertechnetate (99Tcm). With 201T1, all the cases gave a positive result within ten minutes of injection. In 88%, the definition was better, and in five cases (20%) small metastases which were invisible with 99Tcm could be demonstrated with 201T1. This radiotracer seems to promise greater diagnostic precision with an examination time of only 30 minutes.