title: Quantification of LV function and mass by cardiovascular magnetic resonance: multi-center variability and consensus contours.
abstract: BACKGROUND
  High reproducibility of LV mass and volume measurement from cine cardiovascular magnetic resonance (CMR) has been shown within single centers. However, the extent to which contours may vary from center to center, due to different training protocols, is unknown. We aimed to quantify sources of variation between many centers, and provide a multi-center consensus ground truth dataset for benchmarking automated processing tools and facilitating training for new readers in CMR analysis.
  
  
  METHODS
  Seven independent expert readers, representing seven experienced CMR core laboratories, analyzed fifteen cine CMR data sets in accordance with their standard operating protocols and SCMR guidelines. Consensus contours were generated for each image according to a statistical optimization scheme that maximized contour placement agreement between readers.
  
  
  RESULTS
  Reader-consensus agreement was better than inter-reader agreement (end-diastolic volume 14.7 ml vs 15.2-28.4 ml; end-systolic volume 13.2 ml vs 14.0-21.5 ml; LV mass 17.5 g vs 20.2-34.5 g; ejection fraction 4.2 % vs 4.6-7.5 %). Compared with consensus contours, readers were very consistent (small variability across cases within each reader), but bias varied between readers due to differences in contouring protocols at each center. Although larger contour differences were found at the apex and base, the main effect on volume was due to small but consistent differences in the position of the contours in all regions of the LV.
  
  
  CONCLUSIONS
  A multi-center consensus dataset was established for the purposes of benchmarking and training. Achieving consensus on contour drawing protocol between centers before analysis, or bias correction after analysis, is required when collating multi-center results.
authors.affiliation: Department of Anatomy with Radiology, University of Auckland, Auckland, New Zealand. a.suinesiaputra@auckland.ac.nz.
authors.forename: Avan
authors.initials: A
authors.lastname: Suinesiaputra
authors.affiliation: National Institute of Biomedical Imaging and Bioengineering, Bethesda, MD, USA. bluemked@nih.gov.
authors.forename: David A
authors.initials: DA
authors.lastname: Bluemke
authors.affiliation: Department of Anatomy with Radiology, University of Auckland, Auckland, New Zealand. b.cowan@auckland.ac.nz.
authors.forename: Brett R
authors.initials: BR
authors.lastname: Cowan
authors.affiliation: Departments of Medicine and Diagnostic Radiology, McGill University, Montreal, Canada. mgwfriedrich@gmail.com.
authors.forename: Matthias G
authors.initials: MG
authors.lastname: Friedrich
authors.affiliation: University of Virginia, Charlottesville, VA, USA. ckramer@virginia.edu.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Kramer
authors.affiliation: Harvard Medical School, Boston, USA. rykwong@partners.org.
authors.forename: Raymond
authors.initials: R
authors.lastname: Kwong
authors.affiliation: University of Leeds, Leeds, UK. S.Plein@leeds.ac.uk.
authors.forename: Sven
authors.initials: S
authors.lastname: Plein
authors.affiliation: Charité University Medicine Berlin and HELIOS Klinikum Berlin-Buch, Berlin, Germany. jschulzmenger@mac.com.
authors.forename: Jeanette
authors.initials: J
authors.lastname: Schulz-Menger
authors.affiliation: Leiden University Medical Center, Leiden, Netherlands. j.j.m.westenberg@lumc.nl.
authors.forename: Jos J M
authors.initials: JJ
authors.lastname: Westenberg
authors.affiliation: Department of Anatomy with Radiology, University of Auckland, Auckland, New Zealand. a.young@auckland.ac.nz.
authors.forename: Alistair A
authors.initials: AA
authors.lastname: Young
authors.affiliation: Institute for Experimental and Translational Cardiovascular Imaging, DZHK Centre for Cardiovascular Imaging, University Hospital Frankfurt/Main, Frankfurt, Germany. eike.nagel@kcl.ac.uk.
authors.forename: Eike
authors.initials: E
authors.lastname: Nagel
mesh_terms: D000328:Adult; D000368:Aged; D002170:Canada; D016022:Case-Control Studies; D032921:Consensus; D005060:Europe; D005260:Female; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D007090:Image Interpretation, Computer-Assisted; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D014481:United States; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D016277:Ventricular Function, Left