Molecular imaging of a glucagonoma with (18)F-FDG PET/CT and (68)Ga-DOTATATE PET/CT imaging: A case report and review of the literature

A 35-year-old man presented with significant weight loss of 30 kg over the previous 6 months, with newly diagnosed diabetes. Routine laboratory tests were normal, except for markedly elevated blood glucose. Computed tomography (CT) of the abdomen revealed a large severely enhanced mass replacing most of the pancreas and liver metastatic nodules and multiple paraaortic lymph node metastases, (18)F-fluorodeoxygluocse positron emission tomography/computed tomography ((18)F-FDG PET/CT) was performed and revealed mild FDG uptake in the pancreatic mass, as well as mild uptake in the liver and lymph node metastases. A biopsy of the liver metastasis was consistent glucagonoma that was confirmed with markedly elevated serum glucagon level. Subsequently, (68)Ga-DOTATATE PET/CT was performed for better tumor characterization and for assessment of the tumors’ response to therapy, (68)Ga-DOTATATE scan revealed intense uptake in the pancreatic mass, liver metastases, and paraaortic lymph node metastases. The patient responded well to peptide receptor radionuclide therapy. This case highlights the role of both (68)Ga-DOTATATE and (18)FDG-PET/CT in the diagnosis and management of a glucagonoma. (68)Ga-DOTATATE is the tracer of choice for well-differentiated glucagonoma and offers very high diagnostic accuracy as compared with that of cross-sectional and other functional imaging and enables correct patient selection for peptide receptor radionuclide therapy.