18F-FDG PET-CT in Cystic Tumors of the Pancreas

In order to plan treatment or follow-up of pancreatic cystic lesions, is crucial to distinguish benign from malignant cystic tumors with reliable, non-invasive methods. Despite evaluation with several preoperative investigations, a correct pathologic diagnosis rate does not exceed 68%. 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET-CT) has been found to be a highly sensitive and specific non-invasive procedure to detect malignancy in cystic tumors of the pancreas (CTP). The introduction of hybrid PET/CT scans allowed a more accurate localization of the foci of hypermetabolism. We reviewed 14 series (645 patients) with a CTP who underwent 18F-FDG PET-CT from 2001; four of these studies came from our group of investigators (226 patients). In the last studies, sensitivity in detecting malignancy ranged from 83 to 100% and specificity from 78 to 100%. 18F-FDG PET-CT for a long time was used only when conventional imaging was insufficient to rule out a cancer. In our experience, 18F-FDG PET-CT was found to be reliable to detect "cancer in situ" when no other investigations could detect it, so we stress the use of 18F-FDG PET-CT in the first assessment, as alternative to EUS with FNA, to exclude malignancy. We are lacking data about the use of 18F-FDG PET-CT and timing in the follow-up of patients (un)-operated. We suggest a regular use in the follow up of patients with intraductal papillary mucinous neoplasms (IPMN), due to their multifocality and to the high rate of extra-pancreatic cancers.