Introduction:The combined use of 68Gallium [68GA]-DOTA-peptides and 18Fluorine-fluoro-2-deoxyglucose [18F-FDG] PET/TC scans in the work-up of pancreatic neuroendocrine tumors (PanNETs) is controversial. This study aimed at assessing both tracers’ capability to identify tumors and to assess its association with pathological predictors of recurrence.
Methods:Prospectively collected, preoperative, dual-tracer PET/CT scan data of G1-G2, non-metastatic, PanNETs that underwent surgery between January 2013 and October 2019 were retrospectively analyzed.
Results:The final cohort consisted of 124 cases. There was an approximately equal distribution of males and females(50.8%/49.2%), and G1 and G2 tumors(49.2%/50.8%). The disease was detected in 122(98.4%) and 64(51.6%) cases by 68Ga-DOTATOC and by 18F-FDG PET/CT scans, respectively, with a combined sensitivity of 99.2%. 18F-FDG-positive examinations found G2 tumors more often than G1 (59.4% versus 40.6%;p = 0.036), and 18F-FDG-positive PanNETs were larger than negative ones (median tumor size 32 mm, IQR 21 versus 26 mm, IQR 20;p = 0.019). The median Ki67 for 18F-FDG-positive and -negative examinations was 3(IQR 4) and 2(IQR 4), respectively, (p = 0.029). At least one pathologic predictor of recurrence was present in 74.6% of 18F-FDG-positive cases (versus 56.7%;p = 0.039), whereas this was not found when dichotomizing the PanNETs by their dimensions (≤/> 20 mm). None of the two tracers predicted nodal metastasis. ROC curve analysis showed that 18F-FDG uptake higher than 4.2 had a sensitivity of 49.2%, and specificity of 73.3% for differentiating G1 from G2 (AUC=0.624, p=0.009).
Conclusion: The complementary adoption of 68Ga-DOTATOC and 18F-FDG tracers may be valuable in the diagnostic work-up of PanNETs despite not being a game-changer for the management of PanNETs ≤ 20 mm.
Dual-tracer (68Ga-DOTATOC and 18F-FDG-)-PET/CT scan and G1-G2 non-functioning pancreatic neuroendocrine tumors: A single-center retrospective evaluation of 124 non-metastatic resected cases