title: Profiles of US and CT imaging features with a high probability of appendicitis.
abstract: OBJECTIVE
  To identify and evaluate profiles of US and CT features associated with acute appendicitis.
  
  
  METHODS
  Consecutive patients presenting with acute abdominal pain at the emergency department were invited to participate in this study. All patients underwent US and CT. Imaging features known to be associated with appendicitis, and an imaging diagnosis were prospectively recorded by two independent radiologists. A final diagnosis was assigned after 6 months. Associations between appendiceal imaging features and a final diagnosis of appendicitis were evaluated with logistic regression analysis.
  
  
  RESULTS
  Appendicitis was assigned to 284 of 942 evaluated patients (30%). All evaluated features were associated with appendicitis. Imaging profiles were created after multivariable logistic regression analysis. Of 147 patients with a thickened appendix, local transducer tenderness and peri-appendiceal fat infiltration on US, 139 (95%) had appendicitis. On CT, 119 patients in whom the appendix was completely visualised, thickened, with peri-appendiceal fat infiltration and appendiceal enhancement, 114 had a final diagnosis of appendicitis (96%). When at least two of these essential features were present on US or CT, sensitivity was 92% (95% CI 89-96%) and 96% (95% CI 93-98%), respectively.
  
  
  CONCLUSIONS
  Most patients with appendicitis can be categorised within a few imaging profiles on US and CT. When two of the essential features are present the diagnosis of appendicitis can be made accurately.
authors.affiliation: Department of Radiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. a.vanranden@amc.uva.nl
authors.forename: A
authors.initials: A
authors.lastname: van Randen
authors.forename: W
authors.initials: W
authors.lastname: Laméris
authors.forename: H W
authors.initials: HW
authors.lastname: van Es
authors.forename: W
authors.initials: W
authors.lastname: ten Hove
authors.forename: W H
authors.initials: WH
authors.lastname: Bouma
authors.forename: M S
authors.initials: MS
authors.lastname: van Leeuwen
authors.forename: E M
authors.initials: EM
authors.lastname: van Keulen
authors.forename: V P M
authors.initials: VP
authors.lastname: van der Hulst
authors.forename: O D
authors.initials: OD
authors.lastname: Henneman
authors.forename: P M
authors.initials: PM
authors.lastname: Bossuyt
authors.forename: M A
authors.initials: MA
authors.lastname: Boermeester
authors.forename: J
authors.initials: J
authors.lastname: Stoker
mesh_terms: D015746:Abdominal Pain / Q000000981:diagnostic imaging*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001064:Appendicitis / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D004635:Emergency Medicine; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012015:Reference Standards; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography