GLP-1 Receptor Dynamic PET/CT for the diagnosis of pNET: First Clinical Experience

Objectives: The aim of this study was to investigate the feasibility of dynamic protocol for the detection of pancreas neuroendocrine tumor (pNET), and evaluate the tumor biology.

Methods: ⁶⁸Ga-NOTA-MAL-Cys39-exantide was synthesized with automated module. 5 patients with pNET were enrolled in this study, 2 suspected with insulinoma, 3 patients with pNET. All patients underwent ⁶⁸Ga-NOTA-MAL-Cys39-exantide PET-CT. A dynamic acquisition was performed for 1h while initial intravenous injection immediately, followed by conventional static protocol at 60 min post injection. ROI was drawn on the tumor, pancreas, kidney, liver and adrenal, time- radioactivity curves (TACS) were achieved for assessment of biodistributions and kinetics. Final diagnosis was confirmed by histopathology, staging was based on Ki67 proliferation index and mitosis.

Results: Histopathology confirmed that 2 patients with insulinoma, 3 patients with G2 pNET.⁶⁸Ga-NOTA-MAL-Cys39-exantide showed better biodistribution and kinetics, the predominant uptake was in the kidney, little uptake was in the liver and spleen. In insulinoma, dynamic images and TACS found the peak of tumor uptake was appeared about in the in the first minute, followed by plateau phase Whereas ,the uptake in the normal pancreas tissue and other organs showed rapid clearance, except that the uptake in kidney was continuous increased. TACS also revealed these tumors were both artery supplied tumor which associated with benign behavior of pNET.

Conclusion: Dynamic GLP-1 Receptor PET-CT served a valuable tool for the detection of pancreas neuroendocrine tumor and insulinoma, and further contribute to evaluation of tumor biological behavior. Time-radioactivity curves reflect the biodistribution and kinetics ,further study is needed. Research Support: insulinoma; Glucagon-like peptide-1 receptor; somatostatin receptor; PET-CT; Dynamics