title: Magnetic resonance imaging measurement of the anorectal striated muscle complex in normal children.
abstract: OBJECTIVE
  The aim of the study was to describe and establish a normal measurement of the striated muscle complex (SMC) in healthy children using body phased-array or head coil magnetic resonance imaging.
  
  
  METHODS
  Imaging was performed in 20 boys and 20 girls (age range, from 3 months to 14 years; average age, 3.2 years) without anorectal disorders. The dimensions of the puborectalis muscle (PR) and external anal sphincter (EAS) were measured in different planes.
  
  
  RESULTS
  There was a close positive correlation between absolute width and length of SMC and age (P < .05), whereas there was no correlation between the relative width and length of SMC and age (P > .05). Normal relative length of the PR and EAS were measured as 0.47 +/- 0.04 and 0.41 +/- 0.04, respectively, and the normal relative width of PR and posterior EAS were 0.50 +/- 0.04 and 0.44 +/- 0.04 in children younger than 14 years.
  
  
  CONCLUSIONS
  The width and length of PR and EAS increase progressively with age. The relative width and length of PR and EAS were not variable with age. A relative width and length of PR and EAS were chosen as objective criteria for normal SMC in children younger than 14 years.
authors.affiliation: Department of Pediatric Surgery, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China. tshaotao83@126.com
authors.forename: Shaotao
authors.initials: S
authors.lastname: Tang
authors.forename: Qiangsong
authors.initials: Q
authors.lastname: Tong
authors.forename: Yongzhong
authors.initials: Y
authors.lastname: Mao
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.forename: Shiwang
authors.initials: S
authors.lastname: Li
authors.forename: Zhiqing
authors.initials: Z
authors.lastname: Cao
authors.forename: Qinglan
authors.initials: Q
authors.lastname: Ruan
mesh_terms: D000293:Adolescent; D001003:Anal Canal / Q000033:anatomy & histology*; D019412:Anatomy, Cross-Sectional; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology*; D012007:Rectum / Q000033:anatomy & histology*; D012016:Reference Values