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.