A Pilot Study Evaluating 18F-L-Thymidine (FLT) PET Imaging in Children With Gliomas

Background: * Children with brain tumors often have magnetic resonance imaging (MRI) scans to see if the tumor has responded to therapy or to see if the tumor has grown. Sometimes, it is difficult to tell if the scan is abnormal because of tumor size or shape, swelling, scar tissue, or dead tissue. Because brain tumor biopsies require surgery, researchers are looking for more noninvasive ways of evaluating brain tumors. * Positron emission tomography (PET) scans use a radioactive sugar known as 18F-FDG to try to determine if a tumor is active or not. Active tumors generally take up more sugar than the surrounding tissue, but because normal brain tissue uses the same sugar as brain tumors, it is then difficult to tell if tumor tissue is taking up sugar or not. A different radioactive agent, 18F-FLT, is now being studied in some adults with different kinds of tumors. Researchers are interested in determining whether it is possible to use this agent as a marker of tumor activity in children. Objectives: * To determine the safety and effectiveness of 18F-FLT for pediatric glioma scans. * To compare the results of 18F-FLT studies with studies using the radioactive agents 18F-FDG and 1H-MRSI. Eligibility: \- Children less than 18 years of age who are having radiation therapy to treat malignant gliomas. Design: * Participants will have scanning tests before radiation therapy, 1 to 3 weeks after radiation therapy, and if researchers suspect that the tumor is growing. * This study will involve three separate imaging tests (1H-MRSI, 18F-FDG PET, and 18F-FLT PET). * Proton spectroscopy (1H-MRSI) is a procedure that is similar to MRI and is performed in the same scanner as an MRI. Because this scan is long (2-3 hours), most children will receive medications from an anesthesiologist so that they can sleep through the procedure. * Within 2 weeks of the 1H-MRSI scan, participants will have the PET scans with both the standard contrast agent (18F-FDG) and the experimental agent (18F-FLT). These scans will last approximately 1 hour each.

Sex

All

Minimum age

1 Year

Maximum age

17 Years

* INCLUSION CRITERIA:
* Age: 1 year to less than 18 years of age
* Diagnosis: Patients must have a histologic diagnosis of a malignant glioma for which radiation therapy is prescribed. Patients with DIPG or optic pathway gliomas are exempt from this requirement and do not require a histologic diagnosis. All patients must have evaluable (not necessarily measurable) disease.
* Weight less than or equal to 70 kg (to limit radioisotope exposure to maximum adult dose)
* All patients or their legal guardians must sign a document of informed consent indicating their awareness of the investigational nature and risks of this study.
* Organ Function: Patients must have adequate organ function defined as:

Hepatic: SGOT/AST, SGPT/ALT less than 5 times the ULN, Total bilirubin less than or equal to 2 times the ULN

Renal: Serum creatinine within the upper limit of normal values for age

Serum Glucose: less than 150 mg/dL

* Female patients of childbearing potential must have a negative serum or urine pregnancy test
* Patients must be able to undergo both the FLT and FDG PET without the use of general anesthesia.

EXCLUSION CRITERIA:

* Patients unable to undergo MR imaging for any reason (including but not limited to the presence of a metallic implant that is not MRI compatible)
* Pregnant women are excluded because of known harmful effects of radiation on the fetus and the unknown effects of strong magnetic fields and Gadolinium contrast agents on the fetus.
* Any patient with a history of severe reaction (requiring medication) to Gd-DTPA, FDG or FLT.
* Any patient with permanent dental hardware, which, in the judgment of the Principal Investigator, would interfere with obtaining spectroscopy in the area of the tumor.
* Any patient who has begun an investigational agent within 48 hours prior to receiving (18)F-FLT.

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