Somatostatin Receptor Imaging with 68 Ga DOTATATE PET/CT: Clinical Utility, Normal Patterns, Pearls, and Pitfalls in Interpretation

Gallium 68 ((68)Ga) 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-octreotate (DOTATATE, GaTate) positron emission tomography (PET)/computed tomography (CT) is an imaging technique for detecting and characterizing neuroendocrine tumors (NETs). GaTate, a somatostatin analog, has recently been accorded orphan drug status by the U.S. Food and Drug Administration, thereby increasing interest in and availability of this radiotracer. GaTate PET/CT allows whole-body imaging of cell surface expression of somatostatin receptors (SSTRs) and is rapidly evolving as the new imaging standard of reference for the detection and characterization of NETs. The authors discuss the normal appearance at GaTate PET/CT and the utility of this modality in a variety of these tumors, including gastrointestinal, pancreatic, and bronchial NETs as well as pheochromocytoma, paraganglioma, meningioma, and oncogenic osteomalacia. In addition, they discuss potential causes of false-positive findings, including pancreatic uncinate process activity, inflammation, osteoblastic activity, and splenosis. They also highlight the complementary role of 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) PET/CT, including the advantages of using both GaTate PET/CT and FDG PET/CT to evaluate sites of well- and poorly differentiated disease. The use of GaTate PET/CT together with FDG PET/CT allows identification of tumor heterogeneity, which provides prognostic information and can be pivotal in guiding biopsy. It also allows optimal patient management, including theranostic application of peptide receptor radionuclide therapy, and the restaging of patients following therapy.