The purpose of this study is to evaluate diagnostic imaging techniques using 124I-NM404 PET/CT in human brain tumors. This goal will be accomplished by quantifying tumor uptake and determining the optimal PET/CT protocol, comparing PET tumor uptake to MRI, and calculating tumor dosimetry. The long-term goals of this research are to improve the diagnosis and treatment of malignant brain tumors by using radioiodinated NM404

Inclusion Criteria:

• Participants will have a contrast enhanced brain MRI which documents evidence of primary or metastatic brain tumor or suspected tumor recurrence after therapy
• Tumor size at least 1.5 cm in greatest axial dimension on MRI. MRI must be obtained within 2 months of study inclusion
• Adult patients 18 or older
• Female patients must not be pregnant or breast feeding and both women of childbearing potential, and men, must use appropriate means of contraception and must be maintained for at least 45 days after injection of 124I-NM404 Participants must not attempt to become pregnant during this time
• Platelet count must be ≥ 160,000/µl, Hematocrit must be ≥ 22%, Leukocyte count must be ≥ 3,000/µL, Creatinine must be ≤ 2.5 mg/dL, ALT must be ≤ 130 U/L, AST must be ≤ 100 U/L, and urine or serum pregnancy test must be negative for pregnancy
• Patient provides informed consent
• Karnofsky score ≥ 60
• For previously treated brain tumors, targeted brain therapy (radiation or drug) must have concluded ≥2 months prior to injection of 124I-NM404

Exclusion Criteria:

• Life expectancy of < 3 months
• Allergy to potassium iodide (SSKI or Thyroshield)
• Unwilling or unable to complete 3 separate PET/CT imaging sessions of 90 minutes each over 3 days
• Pregnancy or breast-feeding during time of study and/or anticipated breast feeding at any time for 45 days after injection of 124I-NM404.

Adverse event data were collected for up to 48 hours (until the time of the final scan).

Subjects are monitored for adverse events (AEs) by the research team and reported by the principle investigator or co-investigators. Subjects are observed during the injection of 124I-NM404 and for 30 minutes after injection. Subjects are also monitored at each PET/CT scanning session. Approximately 2 - 4 weeks after injection of 124I-NM404, subjects were contacted by phone or other means and/or medical records were reviewed, if available, to assess for any AEs. AE data collection is complete.