title: Studying Dynamic Myofiber Aggregate Reorientation in Dilated Cardiomyopathy Using In Vivo Magnetic Resonance Diffusion Tensor Imaging.
abstract: BACKGROUND
  The objective of this study is to assess the dynamic alterations of myocardial microstructure and strain between diastole and systole in patients with dilated cardiomyopathy relative to healthy controls using the magnetic resonance diffusion tensor imaging, myocardial tagging, and biomechanical modeling.
  
  
  RESULTS
  Dual heart-phase diffusion tensor imaging was successfully performed in 9 patients and 9 controls. Tagging data were acquired for the diffusion tensor strain correction and cardiac motion analysis. Mean diffusivity, fractional anisotropy, and myocyte aggregate orientations were compared between both cohorts. Cardiac function was assessed by left ventricular ejection fraction, torsion, and strain. Computational modeling was used to study the impact of cardiac shape on fiber reorientation and how fiber orientations affect strain. In patients with dilated cardiomyopathy, a more longitudinal orientation of diastolic myofiber aggregates was measured compared with controls. Although a significant steepening of helix angles (HAs) during contraction was found in the controls, consistent change in HAs during contraction was absent in patients. Left ventricular ejection fraction, cardiac torsion, and strain were significantly lower in the patients compared with controls. Computational modeling revealed that the dilated heart results in reduced HA changes compared with a normal heart. Reduced torsion was found to be exacerbated by steeper HAs.
  
  
  CONCLUSIONS
  Diffusion tensor imaging revealed reduced reorientation of myofiber aggregates during cardiac contraction in patients with dilated cardiomyopathy relative to controls. Left ventricular remodeling seems to be an important factor in the changes to myocyte orientation. Steeper HAs are coupled with a worsening in strain and torsion. Overall, the findings provide new insights into the structural alterations in patients with dilated cardiomyopathy.
authors.affiliation: From the Department for Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom (C.v.D., E.S., L.A., D.N., P.L., C.T.S, S.K., R.R.); and Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University and ETH Zurich, Switzerland (C.v.D., C.T.S., S.K.).
authors.forename: Constantin
authors.initials: C
authors.lastname: von Deuster
authors.affiliation: From the Department for Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom (C.v.D., E.S., L.A., D.N., P.L., C.T.S, S.K., R.R.); and Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University and ETH Zurich, Switzerland (C.v.D., C.T.S., S.K.).
authors.forename: Eva
authors.initials: E
authors.lastname: Sammut
authors.affiliation: From the Department for Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom (C.v.D., E.S., L.A., D.N., P.L., C.T.S, S.K., R.R.); and Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University and ETH Zurich, Switzerland (C.v.D., C.T.S., S.K.).
authors.forename: Liya
authors.initials: L
authors.lastname: Asner
authors.affiliation: From the Department for Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom (C.v.D., E.S., L.A., D.N., P.L., C.T.S, S.K., R.R.); and Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University and ETH Zurich, Switzerland (C.v.D., C.T.S., S.K.).
authors.forename: David
authors.initials: D
authors.lastname: Nordsletten
authors.affiliation: From the Department for Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom (C.v.D., E.S., L.A., D.N., P.L., C.T.S, S.K., R.R.); and Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University and ETH Zurich, Switzerland (C.v.D., C.T.S., S.K.).
authors.forename: Pablo
authors.initials: P
authors.lastname: Lamata
authors.affiliation: From the Department for Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom (C.v.D., E.S., L.A., D.N., P.L., C.T.S, S.K., R.R.); and Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University and ETH Zurich, Switzerland (C.v.D., C.T.S., S.K.).
authors.forename: Christian T
authors.initials: CT
authors.lastname: Stoeck
authors.affiliation: From the Department for Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom (C.v.D., E.S., L.A., D.N., P.L., C.T.S, S.K., R.R.); and Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University and ETH Zurich, Switzerland (C.v.D., C.T.S., S.K.). kozerke@biomed.ee.ethz.ch.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kozerke
authors.affiliation: From the Department for Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom (C.v.D., E.S., L.A., D.N., P.L., C.T.S, S.K., R.R.); and Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University and ETH Zurich, Switzerland (C.v.D., C.T.S., S.K.).
authors.forename: Reza
authors.initials: R
authors.lastname: Razavi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D016022:Case-Control Studies; D003198:Computer Simulation; D038524:Diffusion Magnetic Resonance Imaging; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D009200:Myocardial Contraction; D009206:Myocardium / Q000473:pathology*; D009210:Myofibrils / Q000473:pathology*; D011237:Predictive Value of Tests; D013318:Stroke Volume; D054159:Torsion, Mechanical; D016277:Ventricular Function, Left; D020257:Ventricular Remodeling
keywords: diffusion tensor imaging; dilated cardiomyopathy; magnetic resonance imaging; myocardium; myofiber architecture