Complementary role of somatostatin receptor scintigraphy and FDG PET in the evaluation of neuroendocrine tumors

Learning Objectives 1. Review imaging techniques and limitations of somatostatin receptor scintigraphy (SRS) 2. Present several examples of FDG and SRS imaging in the same patient with pathologic correlation.

When evaluating the extent of neuroendocrine tumors (NETs), SRS is part of the standard workup. Although multiple promising agents are being researched, currently, In-111 pentetreotide and F-18 FDG are the only two radiopharmaceuticals approved in the USA for routine clinical imaging of NET’s. Since NETs are a heterogenous group of tumors of varying histological grades and with variable somatostatin receptor expression and density, pentetreotide may not always be the optimal radiopharmacologic imaging agent. We will present paired patient examples of low grade tumors better imaged with SRS SPECT/CT, as well as high grade tumors, whose extent was better imaged with FDG PET/CT. We will review considerations for SRS SPECT/CT versus FDG PET/CT and relate this to tumor pathology