title: Magnetic Resonance Imaging of the anal canal using high resolution sequences and phased array coil: visualization of anal sphincter complex.
abstract: OBJECTIVE
  To assess the normal anatomy of the anal sphincter complex using high-resolution MR imaging with phased -array coil.
  
  
  METHODS
  Twenty patients, 13 males and 7 females, ranging in age between 27 and 56 years underwent MRI evaluation of the pelvic region, using a superconductive 1.5 T magnet (maximum gradient strength, 25 mT/m; minimum rise time 600 microseconds, equipped with phased-array coil. High-resolution T2-weighted Turbo Spin Echo sequences (TR, 4055 ms; TE, 132 ms; matrix 390x512; in-plane resolution, 0.67x0.57 mm) were acquired on multiple axial, sagittal and coronal planes. Images were reviewed by two experienced gastrointestinal radiologists in order to evaluate the normal anal sphincter complex.
  
  
  RESULTS
  Optimal image quality of the anal sphincter complex was obtained in all cases. Different muscular layers were observed between the upper and lower aspects of the anal canal. In the lower part of the anal canal, internal and external sphincter muscles could be observed; in the upper part, puborectal and internal sphincter muscles were depicted. Good visualization of intersphincteric space, levator ani muscle and ischioanal space was also obtained in all cases.
  
  
  CONCLUSIONS
  High-resolution MR images with phased-array coil provide optimal depiction of the anal canal and the anal sphincter complex.
authors.affiliation: Istituto di Radiologia, II Cattedra, Università degli Studi di Roma La Sapienza, Rome, Italy. andrea.laghi@uniroma1.it
authors.forename: A
authors.initials: A
authors.lastname: Laghi
authors.forename: F
authors.initials: F
authors.lastname: Iafrate
authors.forename: P
authors.initials: P
authors.lastname: Paolantonio
authors.forename: R
authors.initials: R
authors.lastname: Iannaccone
authors.forename: I
authors.initials: I
authors.lastname: Baeli
authors.forename: R
authors.initials: R
authors.lastname: Ferrari
authors.forename: C
authors.initials: C
authors.lastname: Catalano
authors.forename: R
authors.initials: R
authors.lastname: Passariello
mesh_terms: D000328:Adult; D001003:Anal Canal / Q000033:anatomy & histology*; D001004:Anus Diseases / Q000175:diagnosis; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged