title: The normal appendix on CT: does size matter?
abstract: OBJECTIVE
  (1) To evaluate the frequency of visualisation and measurements of the normal appendix. (2) To correlate Body Mass Index (BMI) and gender with visualisation of the normal appendix. (3) To correlate age, gender and body length with appendiceal length.
  
  
  METHODS
  A retrospective review of 186 patients undergoing abdominal CT without suspicion of acute appendicitis was done. Frequency of visualisation and measurements (including maximal outer diameter, wall thickness, length, content, location of base and tip) of normal appendices were recorded.
  
  
  RESULTS
  Prevalence of appendectomy was 34.4%. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of visualisation of the normal appendix were 76%, 94%, 96%, 67%, and 82% respectively. The mean maximal diameter of the appendix was 8.19 mm±1.6 (SD) (range, 4.2-12.8 mm). The mean length of the appendix was 81.11 mm±28.44 (SD) (range, 7.2-158.8 mm). The mean wall thickness of the appendix was 2.22 mm±0.56 (SD) (range, 1.15-3.85 mm). The most common location of the appendiceal tip was pelvic in 66% appendices. The most common location of the appendiceal base was inferior, medial, and posterior in 37%. The normal appendix contained high-density material in 2.2%. There was a significant correlation between gender and appendiceal length, with men having longer appendices than women.
  
  
  CONCLUSIONS
  Most normal appendices are seen at multislice CT using i.v. contrast. The maximal outer diameter of the normal appendix overlaps with values currently used to diagnose appendicitis on CT.
authors.affiliation: In vivo Cellular and Molecular Imaging (ICMI) - Vrije Universiteit Brussel, Department of Radiology - UZ Brussel, Brussels, Belgium.
authors.forename: Inneke
authors.initials: I
authors.lastname: Willekens
authors.affiliation: Department of Radiology, ASZ Aalst, Aalst, Belgium.
authors.forename: Els
authors.initials: E
authors.lastname: Peeters
authors.affiliation: Department of Radiology, UZ Brussel, Brussels, Belgium.
authors.forename: Michel
authors.initials: M
authors.lastname: De Maeseneer
authors.affiliation: Department of Radiology, UZ Brussel, Brussels, Belgium.
authors.forename: Johan
authors.initials: J
authors.lastname: de Mey
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001062:Appendectomy / Q000379:methods; D001064:Appendicitis / Q000473:pathology / Q000601:surgery; D001065:Appendix / Q000473:pathology* / Q000601:surgery; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009929:Organ Size / Q000502:physiology*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods