- A diagnostic contrast-enhanced MRI or CT scan of the brain must be performed preoperatively and postoperatively. The postoperative scan must be done within 28 days prior to the initiation of neo-adjuvant TMZ. Preoperative and postoperative scans must be the same type. Patients unable to undergo MR imaging can be enrolled provided pre- and post-operative contrast-enhanced CT scans are obtained and are of sufficient quality.