title: Regional assessment of left ventricular torsion by CMR tagging.
abstract: OBJECTIVE
  To introduce a standardized method for calculation of left ventricular torsion by CMR tagging and to determine the accuracy of torsion analysis in regions using an analytical model.
  
  
  METHODS
  Torsion between base and apex, base and mid, and mid and apex levels was calculated using CSPAMM tagging and Harmonic Phase tracking. The accuracy of torsion analysis on a regional basis (circumferential segments and transmural layers) was analyzed using an analytical model of a deforming cylinder with a displaced axis of rotation (AoR). Regional peak torsion values from twelve healthy volunteers calculated by the described method were compared to literature.
  
  
  RESULTS
  The deviation from the analytical torsion per % AoR-displacement (of the radius) was 0.90 +/- 0.44% for the circumferential segments and only 0.05% for the transmural layers. In the subjects, circumferentially, anterolateral torsion was larger than inferior (12.4 +/- 3.9 degrees vs. 5.0 +/- 3.3 degrees , N.S.). Transmurally, endocardial torsion was smaller than epicardial (7.5 +/- 1.3 degrees vs. 8.0 +/- 1.5 degrees , p < 0.001).
  
  
  CONCLUSIONS
  Variability in the position of the AoR causes a large variability in torsion in circumferential segments. This effect was negligible for global torsion, and torsion calculated in transmural layers. Results were documented for the healthy human heart and are in agreement with data from literature.
authors.affiliation: Dept. of Physics and Medical Technology, Vrije Universiteit Medical Center, De Boelelaan 1118 1081 HV Amsterdam, the Netherlands. i.russel@vumc.nl
authors.forename: Iris K
authors.initials: IK
authors.lastname: Rüssel
authors.forename: Marco J
authors.initials: MJ
authors.lastname: Götte
authors.forename: Joost P
authors.initials: JP
authors.lastname: Kuijer
authors.forename: J Tim
authors.initials: JT
authors.lastname: Marcus
mesh_terms: D000328:Adult; D005260:Female; D006352:Heart Ventricles / Q000033:anatomy & histology*; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D054159:Torsion, Mechanical; D016277:Ventricular Function, Left