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.