title: Acute appendicitis: prospective evaluation of a diagnostic algorithm integrating ultrasound and low-dose CT to reduce the need of standard CT.
abstract: OBJECTIVE
  To evaluate an algorithm integrating ultrasound and low-dose unenhanced CT with oral contrast medium (LDCT) in the assessment of acute appendicitis, to reduce the need of conventional CT.
  
  
  METHODS
  Ultrasound was performed upon admission in 183 consecutive adult patients (111 women, 72 men, mean age 32) with suspicion of acute appendicitis and a BMI between 18.5 and 30 (step 1). No further examination was recommended when ultrasound was positive for appendicitis, negative with low clinical suspicion, or demonstrated an alternative diagnosis. All other patients underwent LDCT (30 mAs) (step 2). Standard intravenously enhanced CT (180 mAs) was performed after indeterminate LDCT (step 3).
  
  
  RESULTS
  No further imaging was recommended after ultrasound in 84 (46%) patients; LDCT was obtained in 99 (54%). LDCT was positive or negative for appendicitis in 81 (82%) of these 99 patients, indeterminate in 18 (18%) who underwent standard CT. Eighty-six (47%) of the 183 patients had a surgically proven appendicitis. The sensitivity and specificity of the algorithm were 98.8% and 96.9%.
  
  
  CONCLUSIONS
  The proposed algorithm achieved high sensitivity and specificity for detection of acute appendicitis, while reducing the need for standard CT and thus limiting exposition to radiation and to intravenous contrast media.
authors.affiliation: Department of Radiology, University Hospital of Geneva, 4 rue Gabrielle Perret-Gentil, 1211, Genève-14, Switzerland. pierre-alexandre.poletti@hcuge.ch
authors.forename: Pierre-Alexandre
authors.initials: PA
authors.lastname: Poletti
authors.forename: Alexandra
authors.initials: A
authors.lastname: Platon
authors.forename: Thomas
authors.initials: T
authors.lastname: De Perrot
authors.forename: Francois
authors.initials: F
authors.lastname: Sarasin
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Andereggen
authors.forename: Olivier
authors.initials: O
authors.lastname: Rutschmann
authors.forename: Elise
authors.initials: E
authors.lastname: Dupuis-Lozeron
authors.forename: Thomas
authors.initials: T
authors.lastname: Perneger
authors.forename: Pascal
authors.initials: P
authors.lastname: Gervaz
authors.forename: Christoph D
authors.initials: CD
authors.lastname: Becker
mesh_terms: D015746:Abdominal Pain / Q000209:etiology*; D000208:Acute Disease; D000328:Adult; D000465:Algorithms; D001064:Appendicitis / Q000150:complications / Q000175:diagnosis* / Q000000981:diagnostic imaging; D015992:Body Mass Index; D003287:Contrast Media; D003362:Cost-Benefit Analysis; D005260:Female; D006801:Humans; D008297:Male; D017410:Practice Guidelines as Topic; D011446:Prospective Studies; D011829:Radiation Dosage; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods; D014463:Ultrasonography
chemical_list: D003287:Contrast Media