Forty-one lesions of intracranial and spinal diseases underwent magnetic resonance (MR) imaging at both standard-dose (0.1 mmol/kg) and double-dose (0.2 mmol/kg) levels of gadolinium (Gd)-DTPA in order to reassess the optimal dose of Gd-DTPA. Each patient received an initial injection of 0.1 mmol/kg and an additional dose of 0.1 mmol/kg 5 min later. In quantitative analysis of contrast enhancement ratios of the enhancing part of the lesion, choroid plexus, cavernous sinus and pituitary stalk were significantly (P < 0.01) increased in double-dose studies. For visual comparison, we defined delineation as the extent to which the lesion may be defined; detectability was defined as the ability to visualize the lesion. With respect to delineation, double-dose studies were superior to standard-dose studies in nine of 20 intraaxial tumor (four of eight malignant gliomas, three of eight benign gliomas and two of four metastatic brain tumors) and five of six cerebral infarcts. The detectability of the lesion was improved in four cases (one astrocytoma, two metastatic brain tumors and one cerebral infarct) in double-dose studies. It was concluded that contrast-enhanced MR imaging using double doses of Gd-DTPA may be useful in the detection and evaluation of the extent of intraaxial lesions enhanced by Gd-DTPA.