title: Differentiation of pancreatic serous cystadenoma from endocrine tumor and intraductal papillary mucinous neoplasm based on washout pattern on multiphase CT.
abstract: OBJECTIVE
  To evaluate the washout (WO) pattern of serous cystadenomas (SCAs) compared with endocrine tumors (ETs) and intraductal papillary mucinous neoplasm (IPMN).
  
  
  METHODS
  Patients with serous cystadenoma (n = 12), ET (n = 29), and IPMN (n = 35) underwent 4-phase computed tomography CT. Tumors were categorized as hyperdense or hypodense. Computed tomographic values measured were unenhanced attenuation (AU), pancreatic attenuation (A12, 12 seconds), portal attenuation (A35), and equilibrium (A158). Computed tomographic parameters calculated were wash-in (WI) = A12 - AU; WO = A12 - A35; and washout ratio (WOR) = WO/WI × 100/22.
  
  
  RESULTS
  Hyperdense SCAs had significantly higher WOR than did hyperdense ETs (P = 0.001). Among the 3 hypodense tumors, SCAs had the significantly highest WOR (P < 0.05/3). Relative to the pancreas, the WOR of SCAs were equivalent, whereas the WOR of ETs and IPMNs were significantly lower.
  
  
  CONCLUSIONS
  Hyperdense SCAs had significantly higher WOR than did hyperdense ETs, and hypodense SCAs had the significantly highest WOR among the three.
authors.affiliation: Department of Radiology, Wakayama Medical University, Wakayama, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Sahara
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kawai
authors.forename: Morio
authors.initials: M
authors.lastname: Sato
authors.forename: Akira
authors.initials: A
authors.lastname: Ikoma
authors.forename: Hiroki
authors.initials: H
authors.lastname: Minamiguchi
authors.forename: Motoki
authors.initials: M
authors.lastname: Nakai
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sanda
authors.forename: Kouhei
authors.initials: K
authors.lastname: Nakata
authors.forename: Taizou
authors.initials: T
authors.lastname: Takeuchi
authors.forename: Takami
authors.initials: T
authors.lastname: Tanaka
authors.forename: Shintaro
authors.initials: S
authors.lastname: Shirai
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Sonomura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D003287:Contrast Media; D003537:Cystadenoma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007472:Iohexol; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol