National Cancer Institute study: evaluation of computed tomography in the diagnosis of intracranial neoplasms. III. Metastatic tumors.

Intracranial metastases were detected in 343 patients in the National Cancer Institute study of computed tomography (CT) in the diagnosis of intracranial tumors. The metastatic lesions were divided into five groups according to the organ of origin. Studies of the attenuation values of the brain lesions showed no distinctive features that would enable the identification of the site of the primary lesion. The sensitivity of CT and angiography was superior to that of radionuclide scanning. Brain metastases showed CT densities less than, equal to, or greater than the normal brain, with attenuation values ranging up to 40. They were found most frequently in the frontal region, and approximately 90% of the lesions showed necrosis. Surrounding edema was usually moderate or marked.