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European Radiology

, Volume 9, Issue 3, pp 436–443 | Cite as

High-resolution magnetic resonance imaging of the anal sphincter using a dedicated endoanal receiver coil

  • N. M. deSouza
  • A. D. Williams
  • D. J. Gilderdale
Abdominal radiology

Abstract.

The use of a surface coil in MR imaging improves signal-to-noise ratio of adjacent tissues of interest. We therefore devised an endoanal receiver coil for imaging the anal sphincter. The probe is solid and re-usable: it comprises a saddle geometry receiver with integral tuning, matching and decoupling. It is placed in the anal canal and immobilised externally. Both in vitro and in vivo normal anatomy is identified. The mucosa is high signal intensity, the submucosa low signal intensity, the internal sphincter uniformly high signal intensity and the external sphincter low signal intensity on T1- and T2-weighted images. In females, the transverse perineal muscle bridges the inferior part of the external sphincter anteriorly. In perianal sepsis, collections and the site of the endoanal opening are identified. In early-onset fecal incontinence following obstetric trauma/surgery, focal sphincter defects are demonstrated; in late-onset fecal incontinence external sphincter atrophy is seen. In fecally incontinent patients with scleroderma, forward deviation of the anterior sphincter musculature with descent of rectal air and feces into the anal canal is noted. The extent of sphincter invasion is assessed in low rectal tumours. In children with congenital anorectal anomalies, abnormalities of the muscle components are defined using smaller-diameter coils. Such information is invaluable in the assessment and surgical planning of patients with a variety of anorectal pathologies.

Key words: MR imaging Endoanal coil Anal sphincter 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • N. M. deSouza
    • 1
  • A. D. Williams
    • 1
  • D. J. Gilderdale
    • 1
  1. 1.Robert Steiner MRI Unit, Department of Radiology, Hammersmith Hospital Campus, Imperial College School of Medicine, Du Cane Road, London W12 0HS, UKGB

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