title: Computed tomography with intravenous contrast alone: the role of intra-abdominal fat on the ability to visualize the normal appendix in children.
abstract: BACKGROUND
  Computed tomography (CT) with enteric contrast is frequently used to evaluate children with suspected appendicitis. The use of CT with intravenous (IV) contrast alone (CT IV) may be sufficient, however, particularly in patients with adequate intra-abdominal fat (IAF).
  
  
  OBJECTIVE
  The authors aimed 1) to determine the ability of radiologists to visualize the normal (nondiseased) appendix with CT IV in children and to assess whether IAF adequacy affects this ability and 2) to assess the association between IAF adequacy and patient characteristics.
  
  
  METHODS
  This was a retrospective 16-center study using a preexisting database of abdominal CT scans. Children 3 to 18 years who had CT IV scan and measured weights and for whom appendectomy history was known from medical record review were included. The sample was chosen based on age to yield a sample with and without adequate IAF. Radiologists at each center reread their site's CT IV scans to assess appendix visualization and IAF adequacy. IAF was categorized as "adequate" if there was any amount of fat completely surrounding the cecum and "inadequate" if otherwise.
  
  
  RESULTS
  A total of 280 patients were included, with mean age of 10.6 years (range = 3.1 to 17.9 years). All 280 had no history of prior appendectomy; therefore, each patient had a presumed normal appendix. A total of 102 patients (36.4%) had adequate IAF. The proportion of normal appendices visualized with CT IV was 72.9% (95% confidence interval [CI] = 67.2% to 78.0%); the proportions were 89% (95% CI = 81.5% to 94.5%) and 63% (95% CI = 56.0% to 70.6%) in those with and without adequate IAF (95% CI for difference of proportions = 16% to 36%). Greater weight and older age were strongly associated with IAF adequacy (p < 0.001), with weight appearing to be a stronger predictor, particularly in females. Although statistically associated, there was noted overlap in the weights and ages of those with and without adequate IAF.
  
  
  CONCLUSIONS
  Protocols using CT with IV contrast alone to visualize the appendix can reasonably include weight, age, or both as considerations for determining when this approach is appropriate. However, although IAF will more frequently be adequate in older, heavier patients, highly accurate prediction of IAF adequacy appears challenging solely based on age and weight.
authors.affiliation: Department of Emergency Medicine, University of Rochester, Galisano Children's Hospital, Rochester, NY.
authors.forename: Madelyn
authors.initials: M
authors.lastname: Garcia
authors.forename: George
authors.initials: G
authors.lastname: Taylor
authors.forename: Lynn
authors.initials: L
authors.lastname: Babcock
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Dillman
authors.forename: Vaseem
authors.initials: V
authors.lastname: Iqbal
authors.forename: Carla V
authors.initials: CV
authors.lastname: Quijano
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Wootton-Gorges
authors.forename: Kathleen
authors.initials: K
authors.lastname: Adelgais
authors.forename: Sudha A
authors.initials: SA
authors.lastname: Anupindi
authors.forename: Sushil
authors.initials: S
authors.lastname: Sonavane
authors.forename: Aparna
authors.initials: A
authors.lastname: Joshi
authors.forename: Murugusundaram
authors.initials: M
authors.lastname: Veeramani
authors.forename: Shireen M
authors.initials: SM
authors.lastname: Atabaki
authors.forename: David J
authors.initials: DJ
authors.lastname: Monroe
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Blumberg
authors.forename: Carrie
authors.initials: C
authors.lastname: Ruzal-Shapiro
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Cook
authors.forename: Peter S
authors.initials: PS
authors.lastname: Dayan
mesh_terms: D000293:Adolescent; D001062:Appendectomy; D001064:Appendicitis / Q000000981:diagnostic imaging*; D001065:Appendix / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media; D005260:Female; D006801:Humans; D050152:Intra-Abdominal Fat / Q000000981:diagnostic imaging*; D016015:Logistic Models; D008297:Male; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media