Dynamic susceptibility contrast (DSC-) MRI provides measures of relative cerebral blood volume (rCBV) in pediatric brain tumors. Correction of rCBV for the effects of contrast agent leakage can be done using post-processing techniques. Forty pediatric patients with high and low grade tumors underwent DSC-MRI scans pre-treatment at four centers. DSC-data was analyzed with and without leakage correction to calculate rCBV and the leakage parameter, K2. There were significant differences between all parameters when comparing the high and low grade tumor groups. Low grade tumors tended to show T1-dominant leakage effects while high grade tumors showed predominantly T2* dominance.