Postcontrast 3-dimensional fluid-attenuated inversion recovery (3D-FLAIR) sequences have reduced vascular and flow-related artifacts and high sensitivity to low gadolinium concentrations. We compared the performance of postcontrast spoiled gradient echo images to 3D-FLAIR in the detection of leptomeningeal metastases in 47 pediatric patients with brain tumors. We found 10 cases with more leptomeningeal signal abnormalities on 3D-FLAIR. Overall there were significantly more lesions on 3D-FLAIR than spoiled gradient echo sequences. We believe the increased detection of leptomeningeal signal abnormality is due to increased sensitivity for low concentrations of gadolinium in regions of early blood brain barrier breakdown. Our study was limited by the lack of leptomeningeal metastases in cerebrospinal fluid sampling. We plan to conduct future studies which will determine whether the time-based concentration of gadolinium affects the performance and results. Future studies will also require more cases of pathology-proven leptomeningeal disease.