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.

The particles will not treat the cancer and any images or information found during this study will not be used for your treatment. The information collected may be used to guide the design of future studies to detect and/or treat tumors.

Inclusion Criteria:

• 18 years of age or older
• Histologically confirmed diagnosis of melanoma or malignant brain tumor at MSKCC
• Newly-diagnosed or recurrent (local,regional, metastatic) metastatic melanoma or malignant brain tumor patients with
• Residual clinically or radiographically evident tumor, including primary cutaneous and mucosal melanomas or malignant brain tumor
• Prior radiation therapy, chemotherapy, or surgery in patients requiring flap reconstruction in the head and neck region.
• Newly diagnosed patients with previous excisional biopsy.
• Normal baseline cardiac function based upon pre-operative evaluation
• At the discretion of the physician ANC>1000/mcl and platelets>100,000/mcl.
• At the discretion of the physician Bilirubin level of < 2.0 mg/dl in the absence of a history of Gilbert's disease (or pattern consistent with Gilbert's).
• If patients have a history of malignancy other than melanoma or malignant brain tumor they must be disease-free (excluding primary cancer for metastatic patients) for ≥ 5 years at the time of enrollment.
• All patients of childbearing and child-creating age must be using an acceptable form of birth control
• Women who are pre-menopausal must have a negative serum pregnancy test

Exclusion Criteria:

• Abnormal thyroid function, such as untreated clinical diagnosis of hypothyroidism, hyperthyroidism, or other thyroid disease
• Known pregnancy or breast-feeding.
• Medical illness unrelated to the tumor which in the opinion of the attending physician and principal investigator will preclude administration of the tracer. This includes patients with uncontrolled infection, chronic renal insufficiency, myocardial infarction within the past 6 months, unstable angina, cardiac arrhythmias other than chronic atrial fibrillation and chronic active or persistent hepatitis, or New York Heart Association Classification III or IV heart disease.
• History of any malignancy (excluding primary cancer for metastatic patients) other than melanoma or malignant brain tumors for which the disease-free interval is <5 years.
• Allergic reaction to iodine-containing contrast material
• Weight greater than the 400-lb weight limit of the PET scanner
• Claustrophobia
• Inability to lie in the scanner for 30 minutes