Comparison of PET and Proton MRS Imaging to Evaluate Pediatric Brain Tumor Activity

This study in children and young adults will compare two types of imaging, positron emission tomography (\[(18)F\]-DG PET) and proton magnetic resonance spectroscopy ((1)H-MRSI), to determine activity of a brain tumor or abnormal tissue in the brain following treatment for a brain tumor. Children with brain tumors are generally followed with magnetic resonance imaging (MRI) scans to evaluate response to treatment. However, because MRI only provides information on the structure of the brain, it may difficult to tell if an abnormal finding is due to tumor, swelling, scar tissue, or dead tissue. (1)H-MRSI and \[(18)F\]-DG PET, on the other hand, provide information on the metabolic activity of brain lesions. These two methods will be compared and evaluated for their ability to provide important additional information on childhood brain tumors. Patients between 1 and 21 years of age with a brain tumor or brain tissue abnormality following treatment for a brain tumor may be eligible for this study. Candidates will be screened with a medical history and physical examination, pregnancy test in women who are able to become pregnant, and a blood test for glucose. Participants will undergo the following procedures: (1)H-MRSI - This test is similar to MRI and is done in the same scanning machine. In MRI, scans of the brain are obtained by applying a strong magnetic field and then collecting the signals released from water after the magnetic field is changed. Pictures of the brain are then obtained by computer analysis of these signals. In (1)H-MRSI, the computer blocks the signal from water to get information on brain chemicals that can indicate whether an abnormality is tumor or dead tissue. Both MRI and MRI and (1)H-MRSI are done in this study. For these tests, the child lies on a stretcher that moves into the scanner - a narrow metal cylinder with a strong magnetic field. The child's head is placed in a headrest to prevent movement during the scan. He or she will hear l