Patients will be enrolled in Arm A first, the FLT-PET cohort, to accommodate the radiological manufacture of the FLT-PET scan dye. It is expensive to manufacture and it is not usable forever. However if a patient is unable to participate in Arm A because of logistical issues, i.e. not being able to travel to UCSF for FLT-PET scans we will offer them participation in Arm B so that they can receive treatment that is not available off study.