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Quantification of Levator Ani Hiatus Enlargement by Magnetic Resonance Imaging in Males and Females with Pelvic Organ Prolapse
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Low muscle volume of the anal sphincter complex: A novel prognostic factor in children with anorectal malformations?

Patricia Feil1, Wilfried Krois1, Michael Weber2

  • 1Division of Pediatric Surgery, Department of Surgery, Medical University of Vienna, MUV, Austria.

Journal of Pediatric Surgery
|November 22, 2021
PubMed

Insights

Magnetic resonance imaging (MRI) allows for feasible measurement of the anal sphincter complex (ASC) volume in infants. Infants with anorectal malformations (ARM) show reduced ASC volumes, with the smallest volumes observed in those with an unfavorable prognosis for fecal continence.

Area of Science:

  • Pediatric imaging
  • Anorectal malformations
  • Sphincter complex anatomy

Background:

  • The anal sphincter complex (ASC) is crucial for continence and often impaired in infants with anorectal malformations (ARM).
  • Magnetic resonance (MR) imaging visualizes the ASC well, but infant volumetric reference data are currently unavailable.
  • This study addresses the need for normative ASC volume data in infants.

Purpose of the Study:

  • To assess the feasibility of MR imaging-based ASC volumetry in infants.
  • To establish reference volumetric data for the infant ASC.
  • To compare ASC volumes in infants with ARM (favorable vs. unfavorable prognosis) against reference data.

Main Methods:

  • Manual segmentation of the ASC was performed on T2-weighted MR images from 76 infants (33 with ARM, 43 controls).
  • Inter-operator agreement was quantified using the intraclass correlation coefficient.
  • Weight-dependent reference data were generated using linear regression, and observed-to-expected ASC volumes were compared between patient groups.

Main Results:

  • ASC volumetry using MRI was feasible in all infants studied.
  • Infants with ARM exhibited significantly lower observed-to-expected ASC volumes compared to controls (-18.1%; p=0.006).
  • A significant difference in observed-to-expected ASC volumes was found between infants with favorable and unfavorable prognoses (p<0.001).

Conclusions:

  • The study confirms the feasibility of MRI-based ASC volumetry in infants.
  • Initial reference data for infant ASC volumes have been established.
  • While ASC volumes were lowest in infants with ARM and unfavorable prognosis, its utility as a prognostic marker requires further investigation.
Abstract

Keywords:
Anal sphincter complexAnorectal malformationMagnetic resonance imagingSegmentationVolumetry

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