title: Accuracy of nonfocused helical CT for the diagnosis of acute appendicitis: a 5-year review.
abstract: OBJECTIVE
  The clinical usefulness of routine, nonfocused helical CT was evaluated in diagnosing acute appendicitis or providing an alternative diagnosis in patients presenting to the emergency department with acute lower abdominal pain.
  
  
  METHODS
  We reviewed CT reports and clinical records of 650 consecutive adult patients who presented between January 1996 and December 2000 with right lower quadrant pain or lower abdominal pain and clinical findings suggestive of appendicitis. Helical CT was performed with oral contrast material in 610 cases (93.8%) and IV contrast in 572 cases (88.0%). Both vascular and enteric contrast media were administered in 544 cases (83.7%). Rectal contrast material was administered in 52 cases (8.0%). The abdomen was helically scanned from the dome of the diaphragm to the iliac crests with a collimation of 7 mm, from the iliac crests to the acetabular roof at a 5-mm collimation, from the acetabular roof to the symphysis pubis with a collimation of 5-10 mm. The surgical or clinical record was used for follow-up.
  
  
  RESULTS
  Of the 650 patients, 552 (84.9%) had adequate clinical follow-up. There were 137 true-positive, eight false-positive, five false-negative, and 402 true-negative cases. The sensitivity, specificity, and accuracy of nonfocused helical CT were 96.5%, 98.0%, 97.6%, respectively. The positive and negative predictive values were 94.5% and 98.8%, respectively. In patients without acute appendicitis, CT suggested an alternative diagnosis, which clinically explained the patient's acute abdominal pain in 266 patients (66.2%).
  
  
  CONCLUSIONS
  Nonfocused helical CT was highly accurate in diagnosing acute appendicitis or suggesting an alternative diagnosis in patients with acute lower abdominal pain or right lower quadrant pain.
authors.affiliation: Department of Radiology, UCLA Center for the Health Sciences, 10833 Le Conte Ave., Los Angeles, CA 90095-1721, USA.
authors.forename: Steven S
authors.initials: SS
authors.lastname: Raman
authors.forename: David S K
authors.initials: DS
authors.lastname: Lu
authors.forename: Barbara M
authors.initials: BM
authors.lastname: Kadell
authors.forename: Darko J
authors.initials: DJ
authors.lastname: Vodopich
authors.forename: James
authors.initials: J
authors.lastname: Sayre
authors.forename: Henry
authors.initials: H
authors.lastname: Cryer
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001064:Appendicitis / Q000000981:diagnostic imaging*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D015203:Reproducibility of Results; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*