We evaluated the usefulness of double-dose (0.2 mmol/kg of gadoteridol) contrast-enhanced magnetic resonance imaging (C-E MRI) in detecting brain metastases of lung cancer. We prospectively enrolled 134 patients with lung cancer who had no neurologic symptoms and who underwent a staging work-up. Patients were assigned to receive both contrast-enhanced computerized tomography (C-E CT) and double-dose C-E MRI. Double-dose C-E MRI detected brain metastases in 19 patients, while C-E CT detected brain metastasis in only 12 of the 19 (P = 0.02). The 3-month survival rate for patients in double-dose C-E MRI group was found to be 2.06 times that of patients in a C-E CT group (P = 0.029), although the survival rate fell to 1.45 (P = 0.387) at 6 months. The results imply that double-dose C-E MRI changed the clinical stage of lung cancer patients. We concluded that double-dose C-E MRI improves the rate of detection of brain metastases during the initial staging of lung cancer.