Molecular imaging of pancreatic neoplasms

Purpose: Pancreatic ductal adenocarcinomas (PDACs) derive from the exocrine pancreas and account for the majority of pancreatic tumors (95%). It is the seventh leading cause of cancer-related deaths and shows one of the worst prognoses in oncology with a 5-year survival rate of 9%. Pancreatic neuroendocrine tumors (pNETs) derive from the endocrine part of the pancreas. Well-differentiated pNETs are characterized by slow tumor growth and good life expectancy. In all pancreatic tumor entities, imaging plays a key role. Hybrid imaging modalities (PET/CT and PET/MRI) combine functional and structural data and may reflect a more accurate assessment of disease spread which directs subsequent treatment planning and patient management. Methods: A comprehensive search strategy was used based on PubMed and SCOPUS databases from 1999 to date. Results: FDG PET/CT in PDAC shows high sensitivity and specificity in evaluation of T- and M-staging but lesser sensitivity of N-staging. In restaging, metabolic changes occur earlier than morphological changes in tumor size and can be assessed by molecular imaging which can act as a predictor of prognosis. 68Ga-labeled somatostatin analogs (SSAs) are the gold standard in imaging of well-differentiated pNETs. In poorly differentiated pNETs, FDG is the radiotracer of choice. PET/MRI may have added value due to higher soft-tissue contrast. However, more prospective studies comparing PET/CT and PET/MRI systems are needed. Conclusion: FDG PET/CT plays a key role in PDAC in staging, restaging as well as disease monitoring during follow-up. Functional imaging with 68Ga-labeled SSA is the gold standard in imaging of well-differentiated pNETs.