Comparison between 68Ga-DOTA-NOC and 18F-DOPA PET for the detection of gastro-entero-pancreatic and lung neuro-endocrine tumours

Purpose F-18-FDG positron emission tomography (PET) value for the assessment of neuro-endocrine tumours (NET) is limited. Preliminary studies indicate that F-18-DOPA and Ga-68-DOTA-NOC are more accurate for disease assessment and Ga-68-DOTA peptides provide additional data on receptor status that are crucial for targeted radionuclide therapy. At present, there are no comparative studies investigating their role in NET. Aim The aim of this study was to compare Ga-68-DOTA-NOC and F-18-DOPA for the evaluation of gastro-entero-pancreatic and lung neuro-endocrine tumours. Materials and methods Thirteen patients with biopsy-proven NET (gastro-entero-pancreatic or pulmonary) were prospectively enrolled and scheduled for F-18-DOPA and Ga-68-DOTA-NOC PET. PET results obtained with both tracers were compared with each other, with other conventional diagnostic procedures (CT, ultrasound) and with follow-up (clinical, imaging). Results The most common primary tumour site was the pancreas (8/13) followed by the ileum (2/13), the lung (2/13) and the duodenum (1/13). The carcinoma was well differentiated in 10/13 and poorly differentiated in 3/13 cases. Ga-68-DOTA-NOC PET was positive, showing at least one lesion, in 13/13 cases while F-18-DOPA PET was positive in 9/13. On a lesions basis, Ga-68-DOTA-NOC identified more lesions than F-18-DOPA (71 vs 45), especially at liver, lung and lymph node level. Ga-68-DOTA-NOC correctly identified the primary site in six of eight non-operated cases (in five cases, the primary was surgically removed before PET), while F-18-DOPA identified the primary only in two of eight cases. Conclusions Although the patients studied are few and heterogeneous, our data show that Ga-68-DOTA-NOC is accurate for the detection of gastro-entero-pancreatic and lung neuro-endocrine tumours in either the primary or metastatic site and that it offers several advantages over F-18-DOPA.