Objective: Patients with Multiple Endocrine Neoplasia Type 1 (MEN1) are at high risk of pancreatic Neuroendocrine Tumours (pNETs). Malignant pNETs develop in one third of MEN1 patients. Structural imaging with CT, Ultrasound and MRI, in conjunction with functional imaging using [68Ga]-DOTA(0)-Tyr(3)-octreotate (68Ga DOTATATE PET/CT) have utility in screening for pNETs, with size criteria (>2-3cm) typically used as an indication for resection, despite pNET size having suboptimal sensitivity and specificity for malignancy.
We sought to determine the utility of Fluorodeoxyglucose (18F) positron emission tomography/computed tomography (18F-FDG PET/CT) imaging in predicting malignant potential of pNETs in patients with MEN1
Design: Retrospective audit.
Patients: All adult MEN1 patients harbouring a common MEN1 mutation at Royal Hobart Hospital, who underwent 18F-FDG PET/CT between 4/2/2010 and 30/4/2016 as part of routine MEN1 surveillance.
Measurements: 18F-FDG PET/CT was compared where available to other structural imaging and surgical histopathology.
Results: Thirty-nine patients underwent sixty-six 18F-FDG PET/CT studies. Thirty-two patients (82.1%) had structural evidence of pNETs (size: mean 24.8mm, range 5.5-64mm).
Of the 32 patients with pNETs, seven (21.9%) underwent surgery [3 based on clinical criteria with no FDG-avidity (7mm, 23mm, 25mm); 4 on both FDG-avidity and size criteria (24mm, 27mm, 36mm, 64mm)]. The Ki67 index was positively associated with FDG avidity. Two of the three patients with FDG-avid pNETs had loco-regional nodal metastases compared to none of those with non-FDG-avid pNETs.
In a further four patients with FDG-avid pancreatic lesions, surgical pathology was unavailable.
None of the remaining 28 patients without FDG avid pNETs subsequently developed evidence of significant pNET size progression or imaging evidence of metastasis over a mean follow-up of 17.5months (median 9 months, range 0-55 months).
Conclusion: 18F-FDG PET/CT is a useful screening modality for identifying MEN1 patients with pNETs of high malignant potential. Surgical resection is recommended for all FDG-avid pNETs.