The purpose of the study is to understand the extent and degree of somatostatin receptor expression in poorly differentiated neuroendocrine carcinomas . This may help to make a determination if a radiolabeled somatostatin analog therapy, also referred to as peptide receptor radiotherapy (PRRT), can be a potential alternative in the future. At this time, radiolabeled somatostatin analogs have not been tested in patients with poorly differentiated neuroendocrine carcinomas, and their efficacy in this disease is not well known Understanding the extent and degree of somatostatin receptor expression is important in order to evaluate the potential of radiolabeled somatostatin analog therapy for treatment of poorly differentiated neuroendocrine carcinomas.

Inclusion Criteria:

• Provision of signed and dated informed consent form
• Stated willingness to comply with all study procedures and availability for the duration of the study
• Male or female ≥ 18 years old
• Histologically confirmed diagnosis of poorly-differentiated neuroendocrine carcinoma of the gastroenteropancreatic tract or unknown primary
• Evidence of measurable disease per RECIST 1.1 on another imagine modality (CT, MRI or FDGPET) with at least 3 tumors >1cm in largest diameter. CT, MRI or Fluorodeoxyglucose (FDG)-PET must have been performed within 2 months of the study scan. (Of note, participants may sign consent for the study prior to scheduling of said CT, MRI or FDG-PET, but will be considered screen failures if the CT/MRI/FDG-PET does not reveal at least 3 tumors >1cm).

Exclusion Criteria:

• Participants with well-differentiated neuroendocrine tumors
• Participants who have undergone 68Ga-dotatate PET scan in the past
• Pregnant women and/or breastfeeding women. Women of child bearing potential must have a negative pregnancy test prior to scan.

Patients of Moffitt Cancer Center's GI Clinic