J Korean Radiol Soc.  1994 Jul;31(1):109-114.

Normal Anatomy of the Anal Wall and Perianal Spaces: An EUS, MRI and Cadaveric Correlative Study

• Bae SH
• Kang HS
• Park KS
• Lee Y
• Chung SY
• Ryu ST

Abstract

PURPOSE
To understand the normal endosonographic anatomy of the perianal spaces, and to evaluate the diagnostic efficacy and limitation of endorectal sonography(EUS), correlative study with MRI, cadaveric sectional image and cadaveric MRI were performed.
MATERIALS AND METHODS
EUS images of the normal 6 perianal spaces (pelvirectal, ischiorectal, intersphincteric, subcutaneous, central, submucous space) which were bounded by internal and external anal sphincters, rectal wall and levator ani muscle were correlated with MRI in 10 normal persons, cadaveric sectional images and cadaveric MRI in 2 cadavers.
RESULTS
Pelvirectal space located superior to levator ani muscle could be demonstrable only on anterior wall scan but could not be visualized on lateral or posterior wall scan on EUS. Five perianal spaces located inferior to levator ani muscle were well seen on anterior, lateral, and posterior wall EUS. MRI was superior to EUS in the evaluation of pelvirectal and ischiorectal spaces but equal or inferior to EUS in the evaluation of intersphincteric, subcutaneous, central and submucous spaces.
CONCLUSION
EUS was valuable in the evaluation of perianal spaces inferior to levator ani muscle but was limited in the evaluation of perianal spaces superior to levator ani muscle.

MeSH Terms

Anal Canal
Cadaver*
Humans
Magnetic Resonance Imaging*