Current tests to detect cancer, including CAT scans and MRI scans, are limited. PET scans use special dyes that are injected into a vein and can better localize possible cancer. The investigators have developed a new particle that can carry a radioactive dye to a very specific area of the tumor. When using a PET scan the radioactive dye can be viewed in areas of possible disease. This particle has been studied in mice and was safe.