title: B-mode and contrast-enhancement characteristics of small nonincidental neuroendocrine pancreatic tumors.
abstract: OBJECTIVE
  Imaging of the pancreas for detection of neuroendocrine tumors is indicated as surveillance in multiple endocrine neoplasia type 1 (MEN1) or if typical clinical symptoms combined with hormone production raise the suspicion of a neuroendocrine tumor. Endoscopic ultrasound (EUS) is considered the best imaging modality to detect small pancreatic tumors. However, little is known about how small pancreatic neuroendocrine tumors (pNETs) present on EUS.
  
  
  METHODS
  In this multicenter study, we retrospectively analyzed the endosonographic characteristics of small pNETs which had been detected due to typical biochemistry and clinical symptoms or during surveillance of MEN 1. Only small pancreatic tumors ≤15 mm with histological confirmation as pNET were included. B-mode and contrast-enhanced ultrasound- and EUS patterns were analyzed.
  
  
  RESULTS
  Among 32 patients with histologically proven small pNETs, 7 patients had known MEN1. Among the pNETs, 20 were insulinoma, 2 gastrinoma, 3 glucagonoma, 6 nonfunctional in MEN1, and one PPoma. 94% of the pNET appeared hypoechogenic, only 1 isoechogenic and 1 hyperechogenic. After contrast injection, 90% of the pNETS showed hyperenhancement compared to the surrounding pancreatic parenchyma.
  
  
  CONCLUSIONS
  The high spatial resolution of EUS allows detection and even cytological confirmation of pNET <7 mm diameter. Hypoechogenicity in B-mode and hyperenhancement after injection of contrast agents are endosonographic characteristics of small pNET and present in >90% of pNETs.
authors.affiliation: Translational Gastroenterology Unit, Oxford University Hospitals, Oxford, UK.
authors.forename: Barbara
authors.initials: B
authors.lastname: Braden
authors.affiliation: Medical Department, Krankenhaus Maerkisch-Oderland, Strausberg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Jenssen
authors.affiliation: Department of Radiology, G.B. Rossi University Hospital, University of Verona, Verona, Italy.
authors.forename: Mirko
authors.initials: M
authors.lastname: D'Onofrio
authors.affiliation: Medical Department, Helios Klinikum Meiningen, Meiningen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Hocke
authors.affiliation: SRH Wald-Klinikum Gera, Gera, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Will
authors.affiliation: Medical Department I/Gastroenterology, Sana Hospital Lichtenberg, Berlin, Germany.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Möller
authors.affiliation: Medical Department, Caritas-Krankenhaus, Uhlandstr. 7 D-97980 Bad Mergentheim, Germany.
authors.forename: Andre
authors.initials: A
authors.lastname: Ignee
authors.affiliation: Department of Ultrasound, Zhongshan Hospital, Fudan University, Shanghai, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Dong
authors.affiliation: Department of Medical Ultrasound, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Xin-Wu
authors.initials: XW
authors.lastname: Cui
authors.affiliation: Department of Gastroenterology, Research Center of Gastroenterology and Hepatology, University of Medicine and Pharmacy Craiova, Craiova, Romania.
authors.forename: Adrian
authors.initials: A
authors.lastname: Sãftoiu
authors.affiliation: Medical Department, Caritas-Krankenhaus, Uhlandstr. 7 D-97980 Bad Mergentheim, Germany; Sino-German Research Center of Ultrasound in Medicine, The first Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
authors.forename: Christoph F
authors.initials: CF
authors.lastname: Dietrich