The role of nuclear medicine in the diagnosis of pancreatic neuroendocrine neoplasms

Abstract

Nuclear medicine plays an important role in the diagnostic management of pancreatic neuroendocrine tumors (NETs)Specific radiopharmaceuticals based on the various biological properties of NETs have been developed, both for conventional scintigraphy and positron emission tomography (PET). In the clinical practice, the choice of the most appropriate radiopharmaceutical depends on several factors, including the biologic characteristics of the tumor (somatostatin receptor status, glucose metabolism, amine metabolism), the clinical information needed (diagnostic or prognostic), and practical issues such as availability and costs. For diagnostic purposes, the choice should be guided by tumor differentiation and grading. In well-differentiated NETs (G1 and low G2), functional imaging with radiolabeled peptides should be performed for lesion identification; in this context, Ga-DOTA-peptide PET/CT is considered the nuclear medicine technique of choice.In-DTPA-octreotide (OctreoScan) SPECT/CT should be considered obsolete for diagnostic purposes and maintains a role only for evaluating the receptor status prior to therapy.F-FDG is the tracer of choice for imaging poorly differentiated NETs (high G2 and G3), where a loss of NET features is expected, and to obtain prognostic information, since the presence of F-FDG-positive lesions correlates with a poor prognosis independently from tumor grading. Other radiopharmaceuticals with a more limited use in pancreatic NETs, i.e F-DOPA and C-5-HTP, are also shortly discussed.