Contemporary Nuclear Medicine Diagnostics of Neuroendocrine Tumors

The new positron emission tomography (PET/CT) methods for neuroendocrine tumors detection are presented and compared with classic, conventional methods. Conventional methods use a gamma scintillation camera for patients with neuroendocrine tumor imaging, after intravenous injection of one of the following radiopharmaceuticals: 1) somatostatin analogues labeled with indium-111 (In-111-pentetreotide) or technetium-99m (Tc-99m-EDDA/HYNIC-TOC); 2) noradrenaline analogue labeled with iodine-131 or -123 (I-131/I-123-MIBG); or 3)Tc-99m(V)-DMSA. Contemporary methods use PET/CT equipment for patients with neuroendocrine tumor imaging, after intravenous injection of pharmaceuticals labeled with positron emitters [fluorine-18(F-18), galium-68 (Ga-68), or carbon-11 (11C)]: 1) glucose analogue ((18)FDG); 2) somatostatin analogue (Ga-68-DOTATOC/Ga-68-DOTATATE/Ga-68-DOTANOC); 3) aminoacid precursors of bioamines: [a) dopamine precursor F-18-DOPA (6-F-18-dihydroxyphenylalanine), b) serotonin precursor C-11-5HTP (C-11-5-hydroxytryptophan)]; or 4) dopamine analogue F-18-DA (6-F-18-fluorodopamine). Conventional and contemporary (PET/CT) somatostatin receptor detection showed identical high specificity (92%), but conventional had very low sensitivity (52%) compared to PET/CT (97%). It means that almost every second neuroendocrine tumor detected by contemporary method cannot be discovered using conventional (classic) method. In metastatic pheochromocytoma detection contemporary (PET/CT) methods (F-18-DOPA and F-18-DA) have higher sensitivity than conventional (I-131/I-123-MIBG) In medullary thyroid carcinoma diagnostics contemporary method (F-18-DOPA) is more sensitive than conventional Tc-89m(V)-DMSA method, and is similar to 18FDG, computed tomography and magnetic resonance. In carcinoid detection contemporary method (F-18-DOPA) shows similar results with contemporary somatostatin receptor detection, while for gastroenteropancreatic neuroendocrine tumors it is worse. To conclude, contemporary (PET/CT) methods for somatostatin receptor detection (Ga-68-DOTATOC/-NOC/-TATE) in neuroendocrine tumors are much more sensitive (almost twice) and more accurate than conventional. Therefore the classical methods should be urgently replaced by contemporary methods.