This trial studies how well 68Ga-DOTATATE digital PET/CT work in diagnosing soft tissue sarcoma. 68Ga-DOTATATE is a radiotracer that may improve image quality of PET imaging. PET is an established imaging technique that utilizes small amounts of radioactivity attached to very minimal amounts of tracer, in the case of this research, 68Ga-DOTATATE. CT images provide an exact outline of organs and potential inflammatory tissue where it occurs in patient's body. 68Ga-DOTATATE digital PET/CT may work better in imaging patients with soft tissue sarcomas.

PRIMARY OBJECTIVE:

I. To assess the feasibility and capability of gallium Ga 68-HA-DOTA-TATE (68Ga-DOTATATE) digital positron emission tomography (dPET)/ computed tomography (CT) imaging for soft tissue sarcomas.

SECONDARY OBJECTIVES:

I. To evaluate the clinical benefit of 68Ga-DOTATATE for a comprehensive assessment of soft tissue sarcomas (STS) using next-generation digital PET detector technology.

II. To describe the perfusion and early tumor uptake kinetics of tumor targets at baseline and following conventional systemic therapy using both 68Ga-DOT AT A TE dPET/CT and 18F-FDG dPET/CT approaches.

III. Using list-mode dPET acquisitions following standard 68Ga-DOTATATE dose administrations, imaging datasets will be retrospectively generated to simulate lower dose or faster image acquisition in order to define further the minimum 68Ga-DOTATATE dose and PET image acquisition times needed to maintain lesion detectability and PET quantification.

V. To assess the feasibility for 68Ga-DOTATATE dPET/CT to identify and stratify STS patients with SSTR2-positive soft tissue sarcoma lesions for future therapy planning using 177Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) for patients with 68Ga-DOTATATE-avid sarcomas.

VI. To assess the safety of 68Ga-DOTATATE in this patient population.

OUTLINE:

Patients receive gallium Ga 68-HA-DOTA-TATE intravenously (IV) and undergo dPET/CT over 60 minutes up to two weeks after starting standard chemotherapy. Beginning 24 hours after gallium Ga 68-HA-DOTA-TATE dPET/CT, patients also receive fludeoxyglucose F-18 IV and undergo dPET/CT over 60 minutes.

Inclusion Criteria:

• Patients >= 18 years of age
• Patients diagnosed with any stage of soft tissue sarcomas candidates for systemic therapies
• Patients with one standard of care PET/CT scan up to 30 days before enrollment at the Ohio State University facilities.

Exclusion Criteria:

• Hypersensitivity to somatostatin or similar peptides
• Somatostatin long-acting analog in the past 6 months
• Patients who are pregnant or lactating
• Patients who are currently incarcerated
• Patients with acute infections
• Inability to complete the needed investigational and standard-of-care imaging examinations due to other reasons (severe claustrophobia, radiation phobia, etc.)
• Patients exceeding the weight limitations of the scanner or are not able to enter the bore of the dPET/CT scanner due to body mass index (BMI)