title: Low-dose abdominal CT for evaluating suspected appendicitis.
abstract: BACKGROUND
  Computed tomography (CT) has become the predominant test for diagnosing acute appendicitis in adults. In children and young adults, exposure to CT radiation is of particular concern. We evaluated the rate of negative (unnecessary) appendectomy after low-dose versus standard-dose abdominal CT in young adults with suspected appendicitis.
  
  
  METHODS
  In this single-institution, single-blind, noninferiority trial, we randomly assigned 891 patients with suspected appendicitis to either low-dose CT (444 patients) or standard-dose CT (447 patients). The median radiation dose in terms of dose-length product was 116 mGy·cm in the low-dose group and 521 mGy·cm in the standard-dose group. The primary end point was the percentage of negative appendectomies among all nonincidental appendectomies, with a noninferiority margin of 5.5 percentage points. Secondary end points included the appendiceal perforation rate and the proportion of patients with suspected appendicitis who required additional imaging.
  
  
  RESULTS
  The negative appendectomy rate was 3.5% (6 of 172 patients) in the low-dose CT group and 3.2% (6 of 186 patients) in the standard-dose CT group (difference, 0.3 percentage points; 95% confidence interval, -3.8 to 4.6). The two groups did not differ significantly in terms of the appendiceal perforation rate (26.5% with low-dose CT and 23.3% with standard-dose CT, P=0.46) or the proportion of patients who needed additional imaging tests (3.2% and 1.6%, respectively; P=0.09).
  
  
  CONCLUSIONS
  Low-dose CT was noninferior to standard-dose CT with respect to negative appendectomy rates in young adults with suspected appendicitis. (Funded by GE Healthcare Medical Diagnostics and others; ClinicalTrials.gov number, NCT00913380.).
authors.affiliation: Department of Emergency Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Gyeonggi-do, South Korea.
authors.forename: Kyuseok
authors.initials: K
authors.lastname: Kim
authors.forename: Young Hoon
authors.initials: YH
authors.lastname: Kim
authors.forename: So Yeon
authors.initials: SY
authors.lastname: Kim
authors.forename: Suyoung
authors.initials: S
authors.lastname: Kim
authors.forename: Yoon Jin
authors.initials: YJ
authors.lastname: Lee
authors.forename: Kwang Pyo
authors.initials: KP
authors.lastname: Kim
authors.forename: Hye Seung
authors.initials: HS
authors.lastname: Lee
authors.forename: Soyeon
authors.initials: S
authors.lastname: Ahn
authors.forename: Taeyun
authors.initials: T
authors.lastname: Kim
authors.forename: Seung-sik
authors.initials: SS
authors.lastname: Hwang
authors.forename: Ki Jun
authors.initials: KJ
authors.lastname: Song
authors.forename: Sung-Bum
authors.initials: SB
authors.lastname: Kang
authors.forename: Duck-Woo
authors.initials: DW
authors.lastname: Kim
authors.forename: Seong Ho
authors.initials: SH
authors.lastname: Park
authors.forename: Kyoung Ho
authors.initials: KH
authors.lastname: Lee
mesh_terms: D000328:Adult; D001062:Appendectomy; D001064:Appendicitis / Q000000981:diagnostic imaging* / Q000601:surgery; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008297:Male; D011829:Radiation Dosage; D016037:Single-Blind Method; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult