Participants in this study have been diagnosed with a tumor such as a carcinoid, neuroendocrine tumor, neuroblastoma, Ewing's sarcoma, or brain tumor that has cells which carry somatostatin receptors.

The purpose of this research study is to see if the tumor can be identified using a special procedure called a positron emission tomography (PET) scan and how the results of this imaging procedure will change the management of the tumor.

This is a prospective, Phase II, single center, open-label study in a total of 200 participants with histologically proven neuroendocrine tumor or other somatostatin receptor positive tumors. Eligible participants will undergo baseline assessments at enrollment. They will receive 68Ga-DOTATOC and undergo a PET/CT imaging study. Participants may receive a second 68Ga-DOTATOC PET/CT for restaging after therapy 12-36 months following the first scan.

Inclusion Criteria:

1. Signed informed consent
2. Age ≥ 6 months
3. Histologically diagnosed neuroendocrine tumor or other tumor with probable somatostatin receptors subtype 2
4. Karnofsky performance status or Lansky Play Scale status of ≥ 60 (or ECOG/WHO equivalent)
5. Subject is male; or is a female who is either surgically sterile (has had a documented bilateral oophorectomy and/or documented hysterectomy), postmenopausal (> 1 years without menses), ≥60 years old,or of childbearing potential for whom a pregnancy test (with the results known prior to investigational product administration) is negative. A negative 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 not capable of becoming pregnant. Female must also be non-lactating.

Exclusion Criteria:

1. Subject weighs more than 450 pounds. (Subjects who weigh more than 450 pounds will not be able to fit inside the imaging machines) or otherwise cannot be safely fit into the imaging system.
2. Inability to lie still for the entire imaging time (due to cough, severe arthritis, etc.)
3. Inability to complete the needed investigational and standard-of-care imaging examinations due to other reasons (severe claustrophobia, radiation phobia, etc.)
4. Any additional medical condition, serious intercurrent illness, or other extenuating circumstance that, in the opinion of the investigator, may significantly interfere with study compliance.
5. Peptide receptor radionuclide therapy (PRRT) within 4 weeks of Ga-68 DOTATOC PET/CT scan.
6. Treatment with Sandostatin LAR within 4 weeks, SQ Octreotide within 12 hours, or Lanreotide injection within 8 weeks of Ga-68 DOTATOC PET/CT (+/-5%).

Adverse events collected at the time of scan, 1 day post scan, and 6-18 months post scan.