Added value of [Ga]Ga-DOTA-TOC PET/CT for characterizing pancreatic neuroendocrine neoplasms: a comparison with contrast-enhanced CT and/or MRI in a large study cohort.

Objectives: To investigate an additional value of [Ga]Ga-DOTA-TOC PET/CT for characterizing suspected pancreatic neuroendocrine neoplasms (NENs) in a large study cohort.

Methods: This retrospective study included 167 patients who underwent [Ga]Ga-DOTA-TOC PET/CT for suspected pancreatic NENs detected by contrast-enhanced CT (n = 153) and/or MRI (n = 85). Two board-certified radiologists independently reviewed CT and/or MRI as well as [Ga]Ga-DOTA-TOC PET/CT and scored the probability of NEN on a 5-point scale. Radiologists' diagnostic performances with and without [Ga]Ga-DOTA-TOC PET/CT were compared using pathologic findings as the standard of reference.

Results: All 167 patients were pathologically diagnosed with NENs (n = 131) or non-NENs (n = 36) by surgery (n = 93) or biopsy (n = 74). The non-NEN group included focal pancreatitis (n = 7), gastrointestinal stromal tumor (n = 6), serous cystadenoma (n = 5), metastatic renal cell carcinoma (n = 4), intrapancreatic accessory spleen (n = 4), ductal adenocarcinoma (n = 3), solid pseudopapillary neoplasm (n = 2), intraductal papillary mucinous carcinoma (n = 1), adenosquamous carcinoma (n = 1), schwannoma (n = 1), paraganglioma (n = 1), and solitary fibrous tumor (n = 1). Radiologists' diagnostic performance significantly improved after the addition of [Ga]Ga-DOTA-TOC PET/CT (AUC of CT: 0.737 vs. 0.886 for reviewer 1 [p = 0.0004]; 0.709 vs. 0.859 for reviewer 2 [p = 0.0002], AUC of MRI: 0.748 vs. 0.872 for reviewer 1 [p = 0.023]; 0.670 vs. 0.854 for reviewer 2 [p = 0.001]). [Ga]Ga-DOTA-TOC PET/CT significantly improved sensitivity (CT: 87.4% vs. 96.6% for reviewer 1 [p = 0.001]; 74.8% vs. 92.5% for reviewer 2 [p = 0.0001], MRI: 86.9% vs. 98.4% for reviewer 1 [p = 0.016]; 70.5% vs. 91.8% for reviewer 2 [p = 0.002]).

Conclusions: [Ga]Ga-DOTA-TOC PET/CT provided an additional value over conventional CT or MRI for the characterization of suspected pancreatic NENs.

Key Points: • [Ga]Ga-DOTA-TOC PET/CT could provide additional value over conventional CT and/or MRI for the exact characterization of suspected pancreatic NENs by increasing AUC values and sensitivity. • Diagnostic improvement was significant, especially in NENs showing an atypical enhancement pattern. • The inter-observer agreement was improved when [Ga]Ga-DOTA-TOC PET/CT was added to CT and/or MRI.