Ferumoxytol, an iron nanoparticle used as an intravascular contrast agent for perfusion magnetic resonance imaging (MRI), has never been explored in the pediatric population. The purpose of this prospective study is to characterize the vascular and permeability properties of pediatric brain tumors using two contrast agents during a single imaging session: ferumoxytol for dynamic susceptibility weighted contrast (DSC) MRI and gadoteridol for dynamic contrast-enhanced (DCE) MRI. In a single imaging session, patients received intravenous ferumoxytol for DSC MRI followed by gadoteridol for DCE MRI. Relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), transfer coefficient (K(trans)), and extravascular extracellular space volume fraction (v(e)) of the brain lesions were calculated. Patients underwent serial imaging sessions over the course of 2 years. Of the 7 patients enrolled thus far, none has experienced an adverse event. Two patients with medulloblastoma were enrolled preoperatively. In the first, rCBV(max), rCBF, K(trans) max, and v(e) max values were 3.74, 3.12, 0.47 min (-1), and 0.08, respectively, while in the second patient, rCBV(max), rCBF, K(trans) max, and v(e) max values were 4.72, 3.47, 0.60 min(-1), and 0.05, respectively. Four patients were enrolled after new gadolinium enhancement was noted in the tumor resection cavity. In 80 % of these lesions, rCBV was <1 suggestive of pseudoprogression secondary to radiochemotherapy. These preliminary results demonstrate that use of ferumoxytol and gadoteridol contrast agents during a single imaging session is feasible, safe, and appears useful for assessing tumor perfusion and permeability characteristics in children.