Imaging of neuroendocrine tumors

The imaging needs in the individual neuroendocrine tumor (NET) patient are very diverse and the choice of method, or combination of techniques, depends on the characteristics of the particular type of NET and its presentation.

The various morphological and functional imaging methods and important methodological aspects are described. The imaging requirements for the various NET subtypes are explained and typical NET image findings are described and illustrated.

The choice of the optimum imaging techniques is not only a matter of sensitivity and specificity but must also be considered in the light of the local availability and expertise in the department. Familiarity with contrast-enhancement technique for computed tomography (CT) and magnetic resonance imaging (MRI) is important in the interpretation and understanding of the imaging results. MRI including diffusion weighted imaging (DWI) for oncological imaging has been reported to improve tumor visualization and reader confidence and is expected to similarly be beneficial for NET imaging. Positron emission tomography (PET) using 68Ga-labeled somatostatin analogs is in several aspects superior to somatostatin receptor scintigraphy using Octreoscan®. Molecular imaging problem-solving tools, when PET/CT using 68Ga-labeled somatostatin analogs fails, are PET/CT with 11C-5-HTP and 18F-DOPA.