title: Quantification of left atrial strain and strain rate using Cardiovascular Magnetic Resonance myocardial feature tracking: a feasibility study.
abstract: BACKGROUND
  Cardiovascular Magnetic Resonance myocardial feature tracking (CMR-FT) is a quantitative technique tracking tissue voxel motion on standard steady-state free precession (SSFP) cine images to assess ventricular myocardial deformation. The importance of left atrial (LA) deformation assessment is increasingly recognized and can be assessed with echocardiographic speckle tracking. However atrial deformation quantification has never previously been demonstrated with CMR. We sought to determine the feasibility and reproducibility of CMR-FT for quantitative derivation of LA strain and strain rate (SR) myocardial mechanics.
  
  
  METHODS
  10 healthy volunteers, 10 patients with hypertrophic cardiomyopathy (HCM) and 10 patients with heart failure and preserved ejection fraction (HFpEF) were studied at 1.5 Tesla. LA longitudinal strain and SR parameters were derived from SSFP cine images using dedicated CMR-FT software (2D CPA MR, TomTec, Germany). LA performance was analyzed using 4- and 2-chamber views including LA reservoir function (total strain [εs], peak positive SR [SRs]), LA conduit function (passive strain [εe], peak early negative SR [SRe]) and LA booster pump function (active strain [εa], late peak negative SR [SRa]).
  
  
  RESULTS
  In all subjects LA strain and SR parameters could be derived from SSFP images. There was impaired LA reservoir function in HCM and HFpEF (εs [%]: HCM 22.1 ± 5.5, HFpEF 16.3 ± 5.8, Controls 29.1 ± 5.3, p < 0.01; SRs [s⁻¹]: HCM 0.9 ± 0.2, HFpEF 0.8 ± 0.3, Controls 1.1 ± 0.2, p < 0.05) and impaired LA conduit function as compared to healthy controls (εe [%]: HCM 10.4 ± 3.9, HFpEF 11.9 ± 4.0, Controls 21.3 ± 5.1, p < 0.001; SRe [s]⁻¹: HCM -0.5 ± 0.2, HFpEF -0.6 ± 0.1, Controls -1.0 ± 0.3, p < 0.01). LA booster pump function was increased in HCM while decreased in HFpEF (εa [%]: HCM 11.7 ± 4.0, HFpEF 4.5 ± 2.9, Controls 7.8 ± 2.5, p < 0.01; SRa [s⁻¹]: HCM -1.2 ± 0.4, HFpEF -0.5 ± 0.2, Controls -0.9 ± 0.3, p < 0.01). Observer variability was excellent for all strain and SR parameters on an intra- and inter-observer level as determined by Bland-Altman, coefficient of variation and intraclass correlation coefficient analyses.
  
  
  CONCLUSIONS
  CMR-FT based atrial performance analysis reliably quantifies LA longitudinal strain and SR from standard SSFP cine images and discriminates between patients with impaired left ventricular relaxation and healthy controls. CMR-FT derived atrial deformation quantification seems a promising novel approach for the study of atrial performance and physiology in health and disease states.
authors.affiliation: Institute for Diagnostic and Interventional Radiology, Georg-August-University, Göttingen, Germany. johanneskowallick@web.de.|DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Göttingen, Germany. johanneskowallick@web.de.
authors.forename: Johannes Tammo
authors.initials: JT
authors.lastname: Kowallick
authors.affiliation: Children's Hospital and Medical Center Joint Division of Pediatric Cardiology, University of Nebraska/Creighton University, Omaha, Nebraska. skutty@unmc.edu.
authors.forename: Shelby
authors.initials: S
authors.lastname: Kutty
authors.affiliation: Department of Cardiology and Pneumology, Georg-August-University, Göttingen, Germany. fedelmann@med.uni-goettingen.de.|DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Göttingen, Germany. fedelmann@med.uni-goettingen.de.
authors.forename: Frank
authors.initials: F
authors.lastname: Edelmann
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, The Rayne Institute, St. Thomas' Hospital, King's College London, London, UK. amedeo.chiribiri@kcl.ac.uk.
authors.forename: Amedeo
authors.initials: A
authors.lastname: Chiribiri
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, The Rayne Institute, St. Thomas' Hospital, King's College London, London, UK. adriana.d.m.villa@gmail.com.
authors.forename: Adriana
authors.initials: A
authors.lastname: Villa
authors.affiliation: Department of Pediatric Cardiology and Intensive Care Medicine, Georg-August-University, Göttingen, Germany. michael.steinmetz@med.uni-goettingen.de.|DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Göttingen, Germany. michael.steinmetz@med.uni-goettingen.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Steinmetz
authors.affiliation: Institute for Diagnostic and Interventional Radiology, Georg-August-University, Göttingen, Germany. jan.sohns@med.uni-goettingen.de.|DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Göttingen, Germany. jan.sohns@med.uni-goettingen.de.
authors.forename: Jan Martin
authors.initials: JM
authors.lastname: Sohns
authors.affiliation: Institute for Diagnostic and Interventional Radiology, Georg-August-University, Göttingen, Germany. wieland.staab@med.uni-goettingen.de.|DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Göttingen, Germany. wieland.staab@med.uni-goettingen.de.
authors.forename: Wieland
authors.initials: W
authors.lastname: Staab
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, The Rayne Institute, St. Thomas' Hospital, King's College London, London, UK. bettencourt.n@gmail.com.|Cardiology Department, Centro Hospitalar de Gaia/Espinho, Vila Nova de Gaia, Portugal. bettencourt.n@gmail.com.
authors.forename: Nuno
authors.initials: N
authors.lastname: Bettencourt
authors.affiliation: Institute for Diagnostic and Interventional Radiology, Georg-August-University, Göttingen, Germany. unterberg@med.uni-goettingen.de.|Department of Cardiology and Pneumology, Georg-August-University, Göttingen, Germany. unterberg@med.uni-goettingen.de.|DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Göttingen, Germany. unterberg@med.uni-goettingen.de.
authors.forename: Christina
authors.initials: C
authors.lastname: Unterberg-Buchwald
authors.affiliation: Department of Cardiology and Pneumology, Georg-August-University, Göttingen, Germany. hasenfus@med.uni-goettingen.de.|DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Göttingen, Germany. hasenfus@med.uni-goettingen.de.
authors.forename: Gerd
authors.initials: G
authors.lastname: Hasenfuß
authors.affiliation: Institute for Diagnostic and Interventional Radiology, Georg-August-University, Göttingen, Germany. joachim.lotz@med.uni-goettingen.de.|DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Göttingen, Germany. joachim.lotz@med.uni-goettingen.de.
authors.forename: Joachim
authors.initials: J
authors.lastname: Lotz
authors.affiliation: Department of Cardiology and Pneumology, Georg-August-University, Göttingen, Germany. andreas_schuster@gmx.net.|Division of Imaging Sciences and Biomedical Engineering, The Rayne Institute, St. Thomas' Hospital, King's College London, London, UK. andreas_schuster@gmx.net.|DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Göttingen, Germany. andreas_schuster@gmx.net.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schuster
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016279:Atrial Function, Left; D001696:Biomechanical Phenomena; D002312:Cardiomyopathy, Hypertrophic / Q000175:diagnosis* / Q000503:physiopathology; D016022:Case-Control Studies; D005240:Feasibility Studies; D005260:Female; D006333:Heart Failure / Q000175:diagnosis / Q000503:physiopathology; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013314:Stress, Mechanical; D013318:Stroke Volume; D016276:Ventricular Function; D055815:Young Adult