13. Residual disease following resection of recurrent tumor is not mandated for eligibility into the study. To best assess the extent of residual disease post-operatively, an MRI should be done no later than 96 hours in the immediate postoperative period or at least 4 weeks postoperatively, within 14 days prior to registration. If the " within 96-hour of surgery " scan is more than 14 days before registration, the scan needs to be repeated.