title: Variability in cardiac MR measurement of left ventricular ejection fraction, volumes and mass in healthy adults: defining a significant change at 1 year.
abstract: OBJECTIVE
  Variability in the measurement of left ventricular (LV) parameters in cardiovascular imaging has typically been assessed over a short time interval, but clinicians most commonly compare results from studies performed a year apart. To account for variation in technical, procedural and biological factors over this time frame, we quantified the within-subject changes in LV volumes, LV mass (LVM) and LV ejection fraction (EF) in a well-defined cohort of healthy adults at 12 months.
  
  
  METHODS
  Cardiac MR (CMR) was performed in 42 healthy control subjects at baseline and at 1 year (1.5 T Magnetom® Avanto; Siemens Healthcare, Erlangen, Germany). Analysis of steady-state free precession images was performed manually offline (Argus software; Siemens Healthcare) for assessment of LV volumes, LVM and EF by a single blinded observer. A random subset of 10 participants also underwent repeat imaging within 7 days to determine short-term interstudy reproducibility.
  
  
  RESULTS
  There were no significant changes in any LV parameter on repeat CMR at 12 months. The short-term interstudy biases were not significantly different from the long-term changes observed at 1 year. The smallest detectable change (SDC) for LVEF, end-diastolic volume, end-systolic volume and LVM that could be recognized with 95% confidence were 6%, 13 ml, 7 ml and 6 g, respectively.
  
  
  CONCLUSIONS
  The variability in CMR-derived LV measures arising from technical, procedural and biological factors remains minimal at 12 months. Thus, for patients undergoing repeat annual assessment by CMR, even small differences in LV function, size and LVM (which are greater than the SDC) may be attributed to disease-related factors.
  
  
  CONCLUSIONS
  The reproducibility and reliability of CMR data at 12 months is excellent allowing clinicians to be confident that even small changes in LV structure and function over this time frame are real.
authors.affiliation: 1 Birmingham CardioRenal Group, Centre for Clinical Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, UK.
authors.forename: W E
authors.initials: WE
authors.lastname: Moody
authors.forename: N C
authors.initials: NC
authors.lastname: Edwards
authors.forename: C D
authors.initials: CD
authors.lastname: Chue
authors.forename: R J
authors.initials: RJ
authors.lastname: Taylor
authors.forename: C J
authors.initials: CJ
authors.lastname: Ferro
authors.forename: J N
authors.initials: JN
authors.lastname: Townend
authors.forename: R P
authors.initials: RP
authors.lastname: Steeds
mesh_terms: D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D005260:Female; D064368:Healthy Volunteers; D006352:Heart Ventricles / Q000033:anatomy & histology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008137:Longitudinal Studies; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D013318:Stroke Volume / Q000502:physiology*; D016277:Ventricular Function, Left / Q000502:physiology*