Materials and Methods: A cross-sectional study was performed to review the impact of 68Ga-DOTA-peptide (68Ga-DOTATATE or 68Ga-DOTATOC) PET/CT on patients with biopsy-proven GI-NET between January 2011 and December 2015. Suspected NET was excluded. Demographic data, tumoral characteristics, change of disease stage, pre-PET intended management and post-PET management were evaluated.

Results: Over a 5-year period, 82 studies of 68Ga-DOTA-peptide PET/CT were performed on 44 GI-NET patients. The most common primary site was the rectum (50.0%) followed by the small bowel, stomach and colon. Using WHO 2010 grading, 40.9% of patients had low-grade (G1) tumour, 22.7% intermediate (G2) and 4.5% high (G3). Of ten patients scheduled for pre-operative staging, 68Ga-DOTA-peptide PET/CT only led to therapeutic change in three patients. Furthermore, false-negative results of 68Ga-DOTA-peptide PET/CT were reported in one patient after surgical confirmation. However, therapeutic changes were seen in 20/36 patients (55.6%) scheduled for post-surgical restaging or assessment of somatostatin analogue (SSA) eligibility. When 68Ga-DOTA-peptide PET/CT was used for monitoring disease progress during systemic treatment (sandostatin, chemotherapy, everolimus and PRRT) in metastatic disease, impact on management modification was seen in 19/36 patients (52.8%), of which 84.2% had inter-modality change (switch to everolimus, chemotherapy or PRRT) and 15.8% had intra-modality change (increased SSA dosage).

MATERIALS AND METHODS: Six patients (M:F = 5:1, age range 28-56 years) with immunohistochemically proven neuroendocrine liver metastases but inconclusive initial CT work-up were retrospectively analysed. Clinical finding, histopathology, comparative imaging and follow-up were used to validate the results when ethically justified.

RESULTS: (68)Ga-DOTATATE PET/CT identified the primary tumour in five out of six (83.3 %) patients: pancreas (n = 4) and stomach (n = 1). Out of three patients with indeterminate primary on initial CT, two patients were confirmed by (68)Ga-DOTATATE PET/CT. Absence of uptake in indeterminate primary of one patient was later confirmed negative by histopathology. In another three patients with undetected primary on initial CT, primary site was demonstrated in all patients with unsuspected metastases in two patients on (68)Ga-DOTATATE PET/ CT. No further work-up was done to confirm the primary in patients with distant metastases. Change of management was observed in three out of six (50 %) patients.