Time-Dependent Changes in the Magnetic Resonance Detection of Brain Metastases Using Single-Dose Gadobutrol

Objectives: The effect of delay in imaging on the assessment of contrast-enhanced magnetic resonance imaging (CE-MRI) has not been extensively studied. This study evaluated the effect of different delay times (3, 7, and 10 minutes) on gadobutrol (Gadovist)enhanced MRI for diagnosis of brain metastases. Patients andMethods: This single-center, blind-reading, post-marketing study enrolled 52 patients with suspected or known brain metastases who received gadolinium-enhanced MR examinations. All the patients received 0.1 mmol/kg dose of gadobutrol, and serial axial T1 FLAIR images were obtained at each MR examination after a delay of 3, 7, and 10 minutes. The images were evaluated by two experienced radiologists independently. The evaluation included subjective and objective evaluations of the image quality. Results: Thirty-four patients were diagnosed with brain metastases. There were 295, 301, and 301 lesions detected in the 3, 7, and 10 minutes delay groups, respectively. Subjective evaluation revealed a higher mean quality score of lesion edge, lesion interior, and overall image quality in the 7 and 10 minutes groups compared to the 3 minutes group. Images in the 7or 10-min delay groups had significantly greater CNR and CBR than the 3-min group (P < 0.05). Conclusion: A delay time of 7 minutes was considered optimal for imaging after gadobutrol administration in patients with brain