Enhancing mass on CT: neoplasm or recent infarction?

On CT, mass effect and contrast enhancement have limited value in separating brain neoplasm from infarct, because both findings are frequent with recent infarction. Review of CT in 100 patients with histologically proven supratentorial lesions (35 infarcts and 65 tumors) indicated the specificity of three helpful signs: (1) White matter edema outlined the uninvolved cortex in 73% of metastases and in 74% of gliomas but only in 14% of infarcts. (2) The cortical ribbon was enhanced in 43% of infarcts, in 7% of gliomas, and in 4% of metastases. (3) Selective sparing of the thalamus occurred in 31% of infarcts but only in 7% of tumors.