Nuclear Medicine and Radiological Imaging of Pancreatic Neuroendocrine Neoplasms: A Multidisciplinary Update

Abstract

Pancreatic neuroendocrine neoplasms (panNENs) are part of a large family of tumors arising from the neuroendocrine system. PanNENs show low–intermediate tumor grade and generally high somatostatin receptor (SSTR) expression. Therefore, panNENs benefit from functional imaging with 68Ga-somatostatin analogues (SSA) for diagnosis, staging, and treatment choice in parallel with morphological imaging. This narrative review aims to present conventional imaging techniques and new perspectives in the management of panNENs, providing the clinicians with useful insight for clinical practice. The 68Ga-SSA PET/CT is the most widely used in panNENs, not only fr diagnosis and staging purpose but also to characterize the biology of the tumor and its responsiveness to SSAs. On the contrary, the 18F-Fluordeoxiglucose (FDG) PET/CT is not employed systematically in all panNEN patients, being generally preferred in G2–G3, to predict aggressiveness and progression rate. The combination of 68Ga-SSA PET/CT and 18F-FDG PET/CT can finally suggest the best therapeutic strategy. Other radiopharmaceuticals are 68Ga-exendin-4 in case of insulinomas and 18F-dopamine (DOPA), which can be helpful in SSTR-negative tumors. New promising but still-under-investigation radiopharmaceuticals include radiolabeled SSTR antagonists and 18F-SSAs. Conventional imaging includes contrast enhanced CT and multiparametric MRI. There are now enriched by radiomics, a new non-invasive imaging approach, very promising to early predict tumor response or progression

Gastroenteropancreatic Neuroendocrine Tumors—Current Status and Advances in Diagnostic Imaging

“…Some tumors do not show noticeable contrast enhancement until the later phase. Small or atypical tumors are associated with high tumor grade and poor prognosis appear homogeneous, and larger ones may appear cystic and inhomogeneous due to central necrosis (Figure 4) [63,64]. Large tumors (>5 cm) are frequently malignant.…”

A Systematic Review on Combined [18F]FDG and 68Ga-SSA PET/CT in Pulmonary Carcinoid

“…In the management of NENs, however, the role of [ 18 F]FDG PET/CT is still a matter of debate, particularly for the evaluation of well differentiated tumors [40,41] but there is solid scientific evidence, that in high-grade tumors there is an upregulation of Glut and glucose metabolism with, often, a loss of SSTR. Indeed, the increase of [ 18 F]FDG uptake correlates with the aggressiveness of neoplasia and indicates a worse prognosis [6,42].…”