title: Effects of slice orientation on reproducibility of sequential assessment of right ventricular volumes and ejection fraction: short-axis vs transverse SSFP cine cardiovascular magnetic resonance.
abstract: BACKGROUND
  Test-retest reproducibility is of utmost importance in follow-up of right ventricular (RV) volumes and function; optimal slice orientation though is not yet known. We compared test-retest reproducibility and intra-/inter-observer variability of right ventricular (RV) volumes and function assessed with short-axis and transverse cardiovascular magnetic resonance (CMR).
  
  
  METHODS
  Eighteen volunteers underwent cine CMR for RV assessment obtaining ventricular coverage in short-axis and transverse slice orientation. Additional 2D phase contrast flow imaging of the main pulmonary artery (MPA) was performed. After complete repositioning repeat acquisitions were performed. Data sets were contoured by two blinded observers. Statistical analysis included Student's t-test, Bland-Altman plots, intra-class correlation coefficient (ICC) and 2-way ANOVA, SEM and minimal detectable difference calculations.
  
  
  RESULTS
  Heart rates (65.0 ± 7.4 vs. 67.6 ± 9.9 bpm; P = 0.1) and MPA flow (89.8 ± 16.6 vs. 87.2 ± 14.9 mL; P = 0.1) did not differ between imaging sessions. EDV and ESV demonstrated an inter-study bias of 0.4 %[-9.5 %,10.3 %] and 2.1 %[-12.3 %,16.4 %] for short-axis and 1.1 %[-7.3 %,9.4 %] and 0.8 %[-16.0 %,17.6 %] for transverse orientation, respectively. There was no significant interaction between imaging orientation and interstudy reproducibility (p = 0.395-0.824), intra-observer variability (p = 0.726-0.862) or inter-observer variability (p = 0.447-0.706) by 2-way ANOVA. Inter-observer agreement by ICC was greater for short axis versus transverse orientation for all parameters (0.769-0.986 vs. 0.625-0.983, respectively). Minimal detectable differences for short axis and transverse orientations were 10.1 mL/11.5 mL for EDV, 8.3 mL/8.4 mL for ESV and 4.1 % vs. 4.7 % for EF, respectively.
  
  
  CONCLUSIONS
  Short-axis and transverse orientation both provide reliable and reproducible measures for follow-up of RV volumes and global function. Therefore, additional transverse SSFP cine CMR may not necessarily be required if performed for the sole purpose of quantitative volumetric RV assessment.
authors.affiliation: Department of Medical Imaging, Peter Munk Cardiac Centre, University Health Network, Toronto, Canada.|Department of Medical Imaging, University of Toronto, Toronto, Canada.
authors.forename: Luigia
authors.initials: L
authors.lastname: D'Errico
authors.affiliation: Department of Medical Imaging, Peter Munk Cardiac Centre, University Health Network, Toronto, Canada.
authors.forename: Mariana M
authors.initials: MM
authors.lastname: Lamacie
authors.affiliation: Department of Medical Imaging, University of Toronto, Toronto, Canada.|Department of Medical Imaging, Sunnybrook Health Science Centre, Toronto, Canada.
authors.forename: Laura
authors.initials: L
authors.lastname: Jimenez Juan
authors.affiliation: Department of Medical Imaging, University of Toronto, Toronto, Canada.|Department of Medical Imaging, St. Michaels Hospital, Toronto, Canada.
authors.forename: Djeven
authors.initials: D
authors.lastname: Deva
authors.affiliation: Department of Medical Imaging, Peter Munk Cardiac Centre, University Health Network, Toronto, Canada.|Department of Medical Imaging, University of Toronto, Toronto, Canada.|Department of Medicine, University of Toronto, Toronto, Canada.
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Wald
authors.affiliation: Department of Medical Imaging, Peter Munk Cardiac Centre, University Health Network, Toronto, Canada.|Department of Medical Imaging, University of Toronto, Toronto, Canada.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Ley
authors.affiliation: Department of Medical Imaging, Peter Munk Cardiac Centre, University Health Network, Toronto, Canada.|Department of Medical Imaging, University of Toronto, Toronto, Canada.
authors.forename: Kate
authors.initials: K
authors.lastname: Hanneman
authors.affiliation: Department of Medical Imaging, Peter Munk Cardiac Centre, University Health Network, Toronto, Canada.|Department of Medicine, University of Toronto, Toronto, Canada.
authors.forename: Paaladinesh
authors.initials: P
authors.lastname: Thavendiranathan
authors.affiliation: Department of Medical Imaging, Peter Munk Cardiac Centre, University Health Network, Toronto, Canada. bernd.wintersperger@uhn.ca.|Department of Medical Imaging, University of Toronto, Toronto, Canada. bernd.wintersperger@uhn.ca.|Department of Medical Imaging, Toronto General Hospital, 1 PMB-273, 585 University Avenue, M5G 2N2, Toronto, ON, Canada. bernd.wintersperger@uhn.ca.
authors.forename: Bernd J
authors.initials: BJ
authors.lastname: Wintersperger
keywords: Cardiac output; Cardiovascular magnetic resonance; Ventricles