title: The relation between organ anatomy and pre-existent vertebral rotation in the normal spine: magnetic resonance imaging study in humans with situs inversus totalis.
abstract: METHODS
  In this cross-sectional magnetic resonance imaging study, vertebral rotation was measured in the transverse plane of the normal, nonscoliotic spine of persons with a complete mirror image reversal of the internal body organs, called situs inversus totalis.
  
  
  OBJECTIVE
  To determine if a pattern of rotation exists in the normal spine of persons with situs inversus totalis, opposite of what was found in humans with normal organ anatomy.
  
  
  BACKGROUND
  In humans, as well as in quadrupeds, the mid and lower thoracic vertebrae of the normal, nonscoliotic spine show a pre-existent pattern of rotation to the right side. This rotational pattern is similar to what is seen in the most prevalent types of adolescent idiopathic scoliosis and, therefore, probably plays an important role in determining the direction of spinal curvature once scoliosis starts to develop. The cause of this pre-existent rotation, however, is unknown.
  
  
  METHODS
  Magnetic resonance imaging scans of the thorax and abdomen of 37 persons with situs inversus totalis and a normal, nonscoliotic spine were acquired to measure axial vertebral rotation from T2 to L5 with a previously developed computer-based measurement method.
  
  
  RESULTS
  The results of this study showed a predominant rotation to the left side of the mid and lower thoracic vertebrae, and to the right side of the upper thoracic and lumbar vertebrae. The mean vertebral rotation angles differed significantly from zero degrees rotation at the mid and lower thoracic levels, with a maximum rotation of 2.7 degrees at level T7 (P < 0.001).
  
  
  CONCLUSIONS
  The normal spine of humans with a situs inversus totalis shows a pre-existent pattern of vertebral rotation opposite of what is seen in humans with normal organ anatomy. This study shows a relation between the asymmetrical position of the thoracic organs and pre-existent vertebral rotation in the normal spine.
authors.affiliation: Department of Orthopedics, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Jan-Willem M
authors.initials: JW
authors.lastname: Kouwenhoven
authors.forename: Lambertus W
authors.initials: LW
authors.lastname: Bartels
authors.forename: Koen L
authors.initials: KL
authors.lastname: Vincken
authors.forename: Max A
authors.initials: MA
authors.lastname: Viergever
authors.forename: Abraham J
authors.initials: AJ
authors.lastname: Verbout
authors.forename: Tammo
authors.initials: T
authors.lastname: Delhaas
authors.forename: René M
authors.initials: RM
authors.lastname: Castelein
mesh_terms: D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008159:Lumbar Vertebrae / Q000002:abnormalities* / Q000033:anatomy & histology / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012399:Rotation; D012600:Scoliosis / Q000000981:diagnostic imaging; D012857:Situs Inversus / Q000473:pathology*; D013904:Thoracic Vertebrae / Q000002:abnormalities* / Q000033:anatomy & histology / Q000473:pathology