68Ga-NODAGA-exendin-4 PET/CT for the localization of insulinomas

Ziel/Aim:

Insulinomas are usually small, single benign tumors. Precise preoperative anatomical localization of the tumor is essential. Imaging techniques like CT, MRI as well as somatostatin receptor (SSTR) imaging have limited sensitivity (1). The stable glucagon like peptide-1 (GLP-1) analog exendin specifically binds the GLP-1 receptor (GLP-1R), which is markedly overexpressed in insulinomas. We propose ⁶⁸Ga-NODAGA-exendin-4 PET/CT as a promising new method for improved localization of insulinomas.

Methodik/Methods:

44 adults aged 24 – 65 with biochemically proven hyperinsulinemic hypoglycemia were included. PET/CT images were obtained one and two hours after injection of (5 – 7 µg) 95 – 105 MBq ⁶⁸Ga-NODAGA-exendin-4. Current standard imaging was performed within 8 weeks of ⁶⁸Ga-NODAGA-exendin-PET in all patients, consisting of CT or MRI and SSTR PET imaging.

Ergebnisse/Results:

In 34 of the patients a focus was identified with one or more of the imaging techniques. Of these patients, 29 have undergone surgery so far and in these patients 34 insulinoma have been removed and pathologically confirmed to be insulin positive tumors. ⁶⁸Ga-NODAGA-exendin-4 PET imaging detected these insulinomas with a sensitivity of 85.3%. Sst-receptor PET and conventional imaging had a sensitivity of 54.5% and 66.7% respectively for detection of these insulinomas. Image quality of ⁶⁸Ga-NODAGA-exendin-4 PET imaging was better than Sst-receptor PET.

Schlussfolgerungen/Conclusions:

In conclusion, ⁶⁸Ga-NODAGA-exendin-4 PET/CT performed better than standard imaging methods, which indicated it is a promising new technique for non-invasive pre-operative detection of insulinomas.

Literatur/References:

[1] Nockel P, Babic B, Millo C, Herscovitch P, Patel D, Nilubol N, et al. Localization of Insulinoma Using 68Ga-DOTATATE PET/CT Scan. The Journal of clinical endocrinology and metabolism. 2017;102(1):195 – 9.