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o(cumulative standard dose) or 0.1 (cumulative triple dose) mmol/kg of gadoteridol to reach the lower-dose level and underwent imaging immediately and 10 and 20 minutes later. Thirty minutes after injection, an additional bolus injection of 0.05 (cumulative standard dose) or 0.2 (cumulative triple dose) mmol/kg was administered to reach the cumulative higher-dose level (cumulative standard dose, 0.1 mmol/kg; cumulative triple dose, 0.3 mmol). Images were acquired immedi-ately. RESULTS: There was no difference in the detection rate for lesions larger than 10mm among T2-weighted, lower-dose immediate and delayed, or immediate higher-dose images in both study groups. Lesions smaller than 10 mm had improved detection with delayed imaging in both study groups; however, the immediate higher-dose studies still had the highest detection rate. CONCLU-SION: In the evaluation of small central nervous system metastases, either delayed imaging after the injection of standard contrast dose or higher contrast dose may improve their detection, and therefore affect clinical management. Higher contrast dose (cumulative triple dose) studies appear to be more effective than delayed imaging with standard dose. Index terms: Brain neoplasms, magnetic resonance; Magnetic resonance, contrast enhancement; Efficacy studies AJNR Am J Neuroradiol 16:373–380, February 1995 The detection of brain metastases requires reasonably high lesion contrast, which depends on the signal of a lesion in relation to the sur-rounding background (1, 2). Several investiga-tors, using gadopentetate dimeglumine at a dose of 0.1 mmol/kg, reported that the signal intensity or lesion contrast of primary and sec-ondary central nervous system lesions in-creased with delayed imaging time (1–6). Im-provement in lesion contrast has also been demonstrated with higher doses of gadolinium (1, 2, 4, 7–11). Lesion contrast or lesion-to-background ratio, therefore, can be improved by using either a higher dose of contrast agent or a lower dose with delayed imaging time. We hypothesized that higher lesion contrast is nec-essary for the detection of small metastatic le-sions (,10 mm) and that immediate high-dose imaging is superior to delayed imaging at stan-dard dose