title: Variance components of two-dimensional strain parameters in the left-ventricular heart wall obtained by magnetic resonance tagging.
abstract: This study quantifies variance components of two-dimensional strains in the left-ventricular heart wall assessed by magnetic resonance (MR) tagging in 18 healthy xxvolunteers. For a 7-mm tagging grid and homogeneous strain analysis, the intersubject variability and measurement error were estimated, as well as the intra- and interobserver variability. The variance components were calculated for the mean strain of a circumferential sector. The results show that the measurement error was almost equal to the intra-observer variability. With four circumferential sectors of 90 degrees each, approximately 65% of the total variance in epsilonr and epsilonc was due to intersubject variability, the remaining 35% was due to measurement error. With 12 sectors of 30 degrees each, the intersubject variability and measurement error both contributed 50% to the total variance. With 18 sectors of 20 degrees each, only 40% of the total variance was due to intersubject variability. The total variability increased with the number of sectors and therefore the number of sectors used in a study will be a trade-off between segment size (defining spatial resolution) and variability.
authors.affiliation: Department of Clinical Physics and Informatics, Institute for Cardiovascular Research ICaR- VU, Amsterdam, The Netherlands. jpa.kuijer@azvu.nl
authors.forename: J P
authors.initials: JP
authors.lastname: Kuijer
authors.forename: J T
authors.initials: JT
authors.lastname: Marcus
authors.forename: M J
authors.initials: MJ
authors.lastname: Götte
authors.forename: A C
authors.initials: AC
authors.lastname: van Rossum
authors.forename: H J
authors.initials: HJ
authors.lastname: Adèr
authors.forename: R M
authors.initials: RM
authors.lastname: Heethaar
mesh_terms: D000704:Analysis of Variance; D005260:Female; D006321:Heart / Q000033:anatomy & histology* / Q000502:physiology; D006352:Heart Ventricles / Q000033:anatomy & histology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D009200:Myocardial Contraction / Q000502:physiology; D012016:Reference Values; D016276:Ventricular Function