Value of 68Ga-DOTATOC and Carbidopa-Assisted 18F-DOPA PET/CT for Insulinoma Localization

J Nucl Med. 2022 Mar;63(3):384-388. doi: 10.2967/jnumed.121.262401. Epub 2021 Jul 16.


Our objective was to assess the value of 68Ga-DOTATOC and carbidopa-assisted 18F-fluorodihydroxyphenylalanine (18F-DOPA) in 21 hypoglycemic patients. Methods: All patients who underwent 68Ga-DOTATOC or carbidopa-assisted 18F-DOPA PET/CT for suspicion of insulinoma from January 2019 to January 2021 were retrospectively analyzed. A final diagnosis of insulinoma was determined by pathologic reports or consensus. Results: During the study period, 21 patients underwent both 68Ga-DOTATOC and 18F-DOPA PET/CT. A final diagnosis of insulin-secreting tumor was reached in 12 cases, including 11 insulinomas and 1 small mixed neuroendocrine/nonneuroendocrine neoplasm. 18F-DOPA and 68Ga-DOTATOC PET/CT were positive in 5 (45%) and 7 (64%) of 11 cases, respectively, with 4 concordant positive findings. Moreover, 1 insulinoma was visualized exclusively by 18F-DOPA PET/CT and 3 by 68Ga-DOTATOC PET/CT only. 18F-DOPA and 68Ga-DOTATOC PET/CT were falsely positive in 1 nonfunctioning pancreatic neuroendocrine tumor. Conclusion: When 68Ga-exendin-4 is not available, 68Ga-somatostatin receptor PET/CT should be the first choice for insulinoma functional imaging.

Keywords: 18F-DOPA; 68Ga-DOTATOC; insulinoma; neuroendocrine tumors; pancreas.

MeSH terms

  • Carbidopa
  • Dihydroxyphenylalanine / analogs & derivatives
  • Gallium Radioisotopes
  • Humans
  • Insulinoma* / diagnostic imaging
  • Neuroendocrine Tumors* / diagnostic imaging
  • Neuroendocrine Tumors* / pathology
  • Octreotide / analogs & derivatives
  • Organometallic Compounds*
  • Pancreatic Neoplasms* / diagnostic imaging
  • Pancreatic Neoplasms* / pathology
  • Positron Emission Tomography Computed Tomography / methods
  • Retrospective Studies


  • Gallium Radioisotopes
  • Organometallic Compounds
  • fluorodopa F 18
  • Dihydroxyphenylalanine
  • Carbidopa
  • Octreotide
  • Edotreotide