This clinical trial studies gallium Ga 68-edotreotide positron emission tomography (PET)/computed tomography (CT) compared with indium In 111 pentetreotide plus contrast-enhanced CT (or MRI) in diagnosing patients with neuroendocrine tumors and other somatostatin receptor positive tumors. Diagnostic procedures, such as gallium Ga 68-edotreotide PET/CT, may help find and diagnose somatostatin receptor positive neuroendocrine tumors. It is not yet known whether Ga 68-edotreotide PET/CT is as effective as indium In 111 pentetreotide plus contrast-enhanced CT (or MRI) in diagnosis and staging of patients with neuroendocrine tumors.

PRIMARY OBJECTIVES:

I. To compare efficacy of [68Ga]-DOTA-tyr3-Octreotide (68Ga-DOTATOC) (gallium Ga 68-edotreotide) PET/CT with Octreoscan (indium In 111 pentetreotide) + high-resolution, contrast-enhanced CT for diagnosis and staging in patients with somatostatin receptor expressing tumors.

OUTLINE:

Patients receive gallium Ga 68-edotreotide intravenously (IV) and undergo PET/CT scan. Within 120 days, patients undergo standard indium In 111 pentetreotide contrast-enhanced CT or MRI scan. Patients may also undergo a second gallium Ga 68-edotreotide PET/CT scan within 3-6 months if the lesions of the first scan cannot be confirmed.

Inclusion Criteria:

• Signed informed consent
• Biopsy proven neuroendocrine tumor, neuroblastoma, medulloblastoma, or other somatostatin receptor positive tumor
• Off Sandostatin (octreotide acetate)-long acting release (LAR) > 4 weeks and off immediate release (subcutaneous) for 12 hrs prior to 68Ga-DOTATOC PET-CT
• Karnofsky performance status or Lansky Play Scale status of >= 50 (or Eastern Cooperative Oncology Group [ECOG]/World Health Organization [WHO] equivalent)
• Subject is male; or is a female who is either pre-menarchal, surgically sterile (has had a documented bilateral oophorectomy and/or documented hysterectomy), postmenopausal (> 1 years without menses), non-lactating, or of childbearing potential for whom a serum pregnancy test (with the results known prior to investigational product administration) is negative; a negative serum pregnancy test will be required for all female subjects with child bearing potential; if a false pregnancy test is suspected, e.g., perimenopausal condition, an obstetrician will be consulted to determine if she is/is capable of becoming pregnant
• No therapy other than Sandostatin since last Octreoscan + diagnostic CT
• Fresh frozen (recommended) or paraffin fixed (required) specimen of primary or metastases available for ribonucleic acid (RNA) and immunohistochemistry (IHC)

Exclusion Criteria:

• Pregnancy or breast feeding
• Surgical resection, chemotherapy, radiation therapy, or biologic therapy since last Octreoscan + CT; continuation of the same dose of Sandostatin-LAR or subcutaneous Sandostatin is allowed
• Medical condition uncontrolled by treatment making completion of study unlikely
• Weight more than 400 pounds (subjects who weigh more than 400 pounds will not be able to fit inside the imaging machines)
• Inability to lie still for the entire imaging time (e.g. cough, severe arthritis, etc.)
• Inability to complete the needed investigational and standard-of-care imaging examinations due to other reasons (severe claustrophobia, radiation phobia, etc.)
• Any additional medical condition, serious intercurrent illness, or other extenuating circumstance that, in the opinion of the investigator, may significantly interfere with study compliance