What is the role of nuclear medicine in the diagnosis of insulinoma?

Updated: May 31, 2020
  • Author: Zonera Ashraf Ali, MBBS; Chief Editor: Neetu Radhakrishnan, MD  more...
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Insulinomas have been shown to have a very high density of glucagon-like peptide–1 (GLP-1) receptors, and radiolabeling GLP-1 analogs (eg, exendin-4) with appropriate radioisotopes can provide noninvasive localization of benign insulinomas. [32, 33] For example, indium-111 (111In)–labeled exendin-4 (111In-DOTA-exendin-4) has successfully been used to localize small insulinomas both preoperatively and, with the use of a gamma probe, intraoperatively. [34] Luo et al reported that PET/CT scanning with gallium-68 (68Ga)-NOTA–exendin-4 correctly detected insulinomas in 42 of 43 patients. [35]

Malignant insulinomas can be missed by GLP-1 target imaging because these tumors often lack GLP-1 receptors. However, these tumors often express somatostatin receptor subtype 2 (SSTR2), which can be detected with indium-111 (111In)-pentetreotide single-photon CT (SPECT). [36, 37, 38]  Nockel et al studied the accuracy of 68Ga–DOTA-(Tyr3)-octreotate (Ga-DOTATATE) PET/CT for localizing insulinoma and suggested that this technique may be considered as an adjunct imaging study when all other imaging studies are negative and when a minimally invasive surgical approach is planned. [7]

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