This trial studies how well an investigational scan called 68Ga-DOTATATE PET/CT works in diagnosing pediatric patients with neuroendocrine tumors that have spread to other places in the body (metastatic). A neuroendocrine tumor is an abnormal growth of neuroendocrine cells, which are cells resembling nerve cells and hormone-producing cells. 68Ga-DOTATATE is a radioactive substance called a radiotracer that when used with PET/CT scans, may work better than standard of care MIBG scans in diagnosing pediatric metastatic neuroendocrine tumors and targeting them with radiation therapy.

PRIMARY OBJECTIVE:

I. To estimate the difference in radiation therapy (RT) target volume definition between gallium Ga 68-DOTATATE (68Ga-DOTATATE) PET/CT and iobenguane (metaiodobenzylguanidine [MIBG]).

SECONDARY OBJECTIVES:

I. To estimate the difference in metastatic tumor burden as detected by 68Ga-DOTATATE PET/CT and MIBG.

II. To estimate the difference in metabolic activity between tumors diagnosed on 68Ga-DOTATATE PET/CT and MIBG.

III. To evaluate patterns of failure after RT in association with 68Ga-DOTATATE PET/CT and MIBG.

OUTLINE: Patients are assigned to 1 of 2 cohorts.

COHORT A: Patients with newly diagnosed high-risk neuroendocrine cancer receive 68Ga-DOTATATE intravenously (IV) and undergo PET/CT over 20-30 minutes at diagnosis (before any treatment) and at the time of radiation treatment planning.

COHORT B: Patients with previously diagnosed high-risk neuroendocrine cancer receive 68Ga-DOTATATE IV and undergo PET/CT over 20-30 minutes at the time of radiation treatment planning.

After completion of study, patients are followed up per standard of care for up to 2 years.

Inclusion Criteria:

• Age =< 30 years
• Histological confirmation of neuroblastoma, ganglioneuroblastoma, or ganglioneuroma.
• High-risk neuroblastoma requiring consolidative RT, as determined by the treating radiation oncologist.
• Eastern Cooperative Oncology Group (ECOG) performance status 0-3 (patients 16 years old or older at entry) or Lansky Score of 30-100 (patients <16 years old at entry).
• Planned for radiation planning and RT at enrolling institution.
• Documented negative pregnancy test prior to induction chemotherapy, for women of childbearing age within =< 7 days prior to registration.
• Willing to return to enrolling institution for follow-up imaging and clinical evaluation, or willing to send follow-up imaging and clinical notes to enrolling institution (during the observation phase of the study).

Exclusion Criteria:

• Pregnant women, nursing women who refuse to stop breastfeeding, or men/women of childbearing age who are unwilling to use an effective birth control method.
• Co-morbid systemic illnesses or other severe concurrent disease which, in the judgment of the investigator, would make the patient inappropriate for entry into this study or interfere significantly with the proper assessment of safety and toxicity of the prescribed regimens.
• Immunocompromised patients and patients known to be human immunodeficiency virus positive and currently receiving antiretroviral therapy. NOTE: Patients known to be human immunodeficiency virus positive, but without clinical evidence of an immunocompromised state, are eligible for this trial.