title: Appendicitis: use of arrowhead sign for diagnosis at CT.
abstract: OBJECTIVE
  To determine the frequency of collection of a contrast medium in the upper portion of the cecum, which the authors call the arrowhead sign, on computed tomographic (CT) scans of the lower abdomen and to assess the sensitivity and specificity of this sign for appendicitis.
  
  
  METHODS
  One hundred consecutive patients clinically suspected of having appendicitis prospectively underwent helical CT limited to the lower abdomen. Contrast media were administered orally and by means of an enema. Each scan was reviewed for the arrowhead sign, and the findings were correlated with surgical and pathologic results or clinical follow-up findings.
  
  
  RESULTS
  The arrowhead sign was present in 17 of 56 cases (30%) of appendicitis and in no case of excluded appendicitis. It allowed the unequivocal diagnosis of appendicitis in four cases (7%) of otherwise non-specific right lower-quadrant inflammation and in one case (2%) of subtle appendicitis seen at CT.
  
  
  CONCLUSIONS
  The arrowhead sign is an often present, highly specific sign of appendicitis that can add specificity to the diagnosis of right lower-quadrant inflammatory processes at CT.
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Boston 02114, USA.
authors.forename: P M
authors.initials: PM
authors.lastname: Rao
authors.forename: J
authors.initials: J
authors.lastname: Wittenberg
authors.forename: R K
authors.initials: RK
authors.lastname: McDowell
authors.forename: J T
authors.initials: JT
authors.lastname: Rhea
authors.forename: R A
authors.initials: RA
authors.lastname: Novelline
mesh_terms: D001064:Appendicitis / Q000000981:diagnostic imaging*; D001466:Barium Sulfate; D002432:Cecum / Q000000981:diagnostic imaging; D003287:Contrast Media; D003974:Diatrizoate Meglumine; D006801:Humans; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D001466:Barium Sulfate; D003974:Diatrizoate Meglumine