Pediatric Radiology

, Volume 46, Issue 7, pp 1003–1010 | Cite as

MRI of the normal appendix in children: data toward a new reference standard

  • David W. SwensonEmail author
  • Gary R. Schooler
  • Catherine Stamoulis
  • Edward Y. Lee
Original Article



Magnetic resonance imaging (MRI) might prove useful in the diagnostic evaluation of pediatric appendicitis in the effort to avoid exposing children to the ionizing radiation of CT, yet there is a paucity of literature describing the normal range of appearances of the pediatric appendix on MRI.


To investigate MRI characteristics of the normal appendix to aid in establishing a reference standard in the pediatric population.

Materials and methods

We conducted a retrospective study of children and young adults (≤18 years of age) who underwent lumbar spine or pelvis MRI between Jan. 1, 2013, and Dec. 31, 2013, for indications unrelated to appendicitis. Two board-certified radiologists independently reviewed all patients’ MRI examinations for appendix visualization, diameter, intraluminal content signal, and presence of periappendiceal inflammation or free fluid. We used the Cohen kappa statistic and Spearman correlation coefficient to assess reader agreement on qualitative and quantitative data, respectively.


Three hundred forty-six patients met inclusion criteria. Both readers visualized the appendix in 192/346 (55.5%) patients (kappa = 0.88, P < 0.0001). Estimated median appendix diameter was 5 mm for reader 1 and 6 mm for reader 2 ([25th, 75th] quartiles = [5, 6] mm; range, 2–11 mm; r = 0.81, P < 0.0001). Appendix intraluminal signal characteristics were variable. Periappendiceal inflammation was present in 0/192 (0%) and free fluid in 6/192 (3.1%) MRI examinations (kappa = 1.0).


The normal appendix was seen on MRI in approximately half of pediatric patients, with a mean diameter of ~5–6 mm, variable intraluminal signal characteristics, no adjacent inflammatory changes, and rare surrounding free fluid.


Appendix Children Magnetic resonance imaging Normal reference standard 


Compliance with ethical standards

Conflicts of interest



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Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • David W. Swenson
    • 1
    Email author
  • Gary R. Schooler
    • 2
  • Catherine Stamoulis
    • 3
  • Edward Y. Lee
    • 3
  1. 1.Department of Diagnostic ImagingAlpert Medical School of Brown University and Rhode Island HospitalProvidenceUSA
  2. 2.Department of RadiologyDuke University Medical CenterDurhamUSA
  3. 3.Department of RadiologyBoston Children’s Hospital and Harvard Medical SchoolBostonUSA

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