Advances in the imaging of gastroenteropancreatic neuroendocrine neoplasms

Abstract

Gastroenteropancreatic neuroendocrine neoplasms comprise a heterogeneous group of tumors that differ in their pathogenesis, hormonal syndromes produced, biological behavior and consequently, in their requirement for and/or response to specific chemotherapeutic agents and molecular targeted therapies. Various imaging techniques are available for functional and morphological evaluation of these neoplasms and the selection of investigations performed in each patient should be customized to the clinical question. Also, with the increased availability of cross sectional imaging, these neoplasms are increasingly being detected incidentally in routine radiology practice. This article is a review of the various imaging modalities currently used in the evaluation of neuroendocrine neoplasms, along with a discussion of the role of advanced imaging techniques and a glimpse into the newer imaging horizons, mostly in the research stage.

Keywords: Neuroendocrine tumor; Gastroenteropancreatic; Intravoxel incoherent motion; Diffusion weighted imaging; Perfusion imaging; Dual energy computed tomography

Core Tip: The prognosis of gastroenteropancreatic neuroendocrine neoplasms (GEPNENs) depends on the stage of the disease and tumor grade. Traditional imaging techniques like multiphase contrast-enhanced computed tomography perform well at disease staging. For tumor grading, histopathological examination, with determination of number of mitoses and Ki-67 index is considered optimal. Advances in imaging techniques have enabled detection of smaller neuroendocrine neoplasms (< 2 cm). By analysing functional information like diffusion, perfusion and tumor heterogeneity, quantitative imaging is currently focused on noninvasive prediction of the grade of GEPNENs preoperatively.