Detection of brain metastases from lung cancer by CT and MRI

To compare the detectability of brain metastases from lung cancer, both CT and MRI were performed on all patients. Thirty-two lung cancer patients with brain metastases admitted from December 1990 to June 1994 were examined by CT and MRI using contrast enhancement. Six radiologists individually evaluated CT and MRI films for brain metastases. In 3 of 32 cases, multiple small metastatic lesions which could not be detected on CT were detected on MRI. In 29 of the 32 cases, 56 metastatic lesions were detected on CT, whereas 103 lesions were detected on MRI. There were no lesions that were detected only by CT and were not detected by MRI. MRI was superior to CT for determining small lesions less than 9 mm and inferior tentorial lesions. As a result, we consider that CT is not sufficiently effective for detecting brain metastases of lung cancer, and that MRI is now indispensable.