A Frequency and Semiquantitative Analysis of Pathological 68Ga DOTATATE PET/CT Uptake by Primary Site–Dependent Neuroendocrine Tumor Metastasis

The aim of this study was to define the frequency of neuroendocrine neoplasia (NEN) metastasis sites based on the primary lesion and create a database of SUVmax as a marker of human SSTR (somatostatin receptors) expression by semiquantitative analysis in vivo 68Ga DOTATATE PET/CT. Patients and Methods Two hundred forty-five patients, 89 men and 156 women (mean [SD] age, 56.1 [12.8]), were imaged 60 to 70 minutes after 120 to 200 MBq (3.2-5.4 mCi) 68Ga DOTATATE injection using a Siemens Medical Solutions Biograph 64 PET/CT TruePoint. Visual assessments were made using a multimodality workstation, and sites of increased uptake were recorded. Pathological 68Ga DOTATATE uptake was quantified using semiquantitative analysis (SUVmax). Results In patients with unknown primary tumors, 68Ga DOTATATE PET/CT revealed primary location in 92% (pancreas, 47%; intestines, 28%; and lung, 17%). Metastases, with respect to the primary sites, were predominantly in the liver (33% vs 49% vs 40%), lymph nodes (24% vs 34% vs 25%), and bone (10% vs 20% vs 30%). The SUVmax of metastases (mean [SD]) was highest in the liver (28.7 [23.5]), followed by the adrenal glands (24.7 [9.7]), bone (24.1 [36.8]), lymph nodes (22.5 [24.5]), pancreas (24.9 [28.1]), peritoneum (21.9 [24]), and the brain (4.6 [2.9]). Conclusions 68Ga DOTATATE PET/CT is very useful in the localization of NEN primary tumors. 68Ga DOTATATE PET/CT allows for visualizations of bone and lymph node metastases, not detected by any other modalities, which provides better staging and changes the clinical decision in approximately one third of patients. Our study shows that pancreatic NEN presented statistically a significantly lower frequency of bone metastases in comparison to lung and intestinal NEN. No significant frequency of metastases in the liver and lymph nodes based on primary tumors was observed.