Methionine PET/CT Studies In Patients With Cancer

Overview

The purpose of this study is to test the usefulness of imaging with radiolabeled methionine in the evaluation of children and young adults with tumor(s). Methionine is a naturally occurring essential amino acid. It is crucial for the formation of proteins. When labeled with carbon-11 (C-11), a radioactive isotope of the naturally occurring carbon-12, the distribution of methionine can be determined noninvasively using a PET (positron emission tomography) camera. C-11 methionine (MET) has been shown valuable in the monitoring of a large number of neoplasms. Since C-11 has a short half life (20 minutes), MET must be produced in a facility very close to its intended use. Thus, it is not widely available and is produced only at select institutions with access to a cyclotron and PET chemistry facility. With the new availability of short lived tracers produced by its PET chemistry unit, St. Jude Children's Research Hospital (St. Jude) is one of only a few facilities with the capabilities and interests to evaluate the utility of PET scanning in the detection of tumors, evaluation of response to therapy, and distinction of residual tumor from scar tissue in patients who have completed therapy. The investigators propose to examine the biodistribution of MET in patients with malignant solid neoplasms, with emphasis on central nervous system (CNS) tumors and sarcomas. This project introduces a new diagnostic test for the noninvasive evaluation of neoplasms in pediatric oncology. Although not the primary purpose of this proposal, the investigators anticipate that MET studies will provide useful clinical information for the management of patients with malignant neoplasms.

The study focuses on the following objectives: Primary objective: * To estimate the success rate of Methionine (MET) for visualizing tumors at the time of diagnosis. The study hypothesizes that at least 70% of newly diagnosed tumors within each group will be studied and will be successfully visualized. Secondary objective: * To compare uptake of MET in tumors with tumor grade in patients with newly diagnosed or relapsed, and/or persistent disease. Hypothesis: high grade tumors will concentrate higher amounts of MET than lower grade tumors measured both qualitatively and semi-quantitatively. * To examine the bio-distribution of MET in organs that do not contain tumor, in particular the lungs, heart, mediastinum, liver, spleen, pancreas, muscle, brain, and bone marrow. Exploratory objectives: * To compare the findings on MET PET scans with those of standard imaging modalities, principally MRI (magnetic resonance imaging) and FDG (fluorodeoxyglucose) PET CT (computed tomography) at diagnosis, or at study enrollment for patients with relapsed and or persistent disease, and for all patients over time. * To compare the extent of abnormality on MRI with that of MET. * To determine the presence or absence of elevated MET uptake beyond those of MRI defined abnormality. * To explore the relationship between MET uptake and prognosis.