title: Comparison of long and short axis quantification of left ventricular volume parameters by cardiovascular magnetic resonance, with ex-vivo validation.
abstract: BACKGROUND
  The purpose of the study was to compare the accuracy and evaluation time of quantifying left ventricular (LV), left atrial (LA) volume and LV mass using short axis (SAX) and long axis (LAX) methods when using cardiovascular magnetic resonance (CMR).
  
  
  METHODS
  We studied 12 explanted canine hearts and 46 patients referred for CMR (29 male, age 47 ± 18 years) in a clinical 1.5 T CMR system, using standard cine sequences. In standard short axis stacks of various slice thickness values in dogs and 8 mm slice thickness (gap 2 mm) in patients, we measured LV volumes using reference slices in a perpendicular, long axis orientation using certified software. Volumes and mass were also measured in six radial long axis (LAX) views.LV parameters were also assessed for intra- and inter-observer variability. In 24 patients, we also analyzed reproducibility and evaluation time of two very experienced (> 10 years of CMR reading) readers for SAX and LAX.
  
  
  RESULTS
  In the explanted dog hearts, there was excellent agreement between ex vivo data and LV mass and volume data as measured by all methods for both, LAX (r² = 0.98) and SAX (r² = 0.88 to 0.98). LA volumes, however, were underestimated by 13% using the LAX views. In patients, there was a good correlation between all three assessed methods (r² ≥ 0.95 for all). In experienced clinical readers, left-ventricular volumes and ejection fraction as measured in LAX views showed a better inter-observer reproducibility and a 27% shorter evaluation time.
  
  
  CONCLUSIONS
  When compared to an ex vivo standard, both, short axis and long axis techniques are highly accurate for the quantification of left ventricular volumes and mass. In clinical settings, however, the long axis approach may be more reproducible and more time-efficient. Therefore, the rotational long axis approach is a viable alternative for the clinical assessment of cardiac volumes, function and mass.
authors.affiliation: Stephenson Cardiovascular MR Centre at Libin Cardiovascular Institute of Alberta, Departments of Cardiac Sciences and Radiology, University of Calgary, AB, Canada.
authors.forename: Helene
authors.initials: H
authors.lastname: Childs
authors.forename: Lucia
authors.initials: L
authors.lastname: Ma
authors.forename: Michael
authors.initials: M
authors.lastname: Ma
authors.forename: James
authors.initials: J
authors.lastname: Clarke
authors.forename: Myra
authors.initials: M
authors.lastname: Cocker
authors.forename: Jordin
authors.initials: J
authors.lastname: Green
authors.forename: Oliver
authors.initials: O
authors.lastname: Strohm
authors.forename: Matthias G
authors.initials: MG
authors.lastname: Friedrich
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D002170:Canada; D002983:Clinical Competence; D004285:Dogs; D005260:Female; D006325:Heart Atria / Q000473:pathology; D006352:Heart Ventricles / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; 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; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000503:physiopathology; D016277:Ventricular Function, Left; D055815:Young Adult