Quantification of myocardial function using MRI feature tracking in children - Determination of normal values

Introduction: Cardiac MR feature tracking imaging (FTI) uses a 2D-deforming analysis of the myocardium to quantify myocardial motion and contractility. The aim of this study was to determine normal values of left ventricular (LV) strain and strain rate (SR) in healthy children. Method: Eighty children from 2 centres (age: 12±5.5 y, range: 1 to 17 y; 39 f; divided into 3 groups: 0-11y (n=24), 11-15y (n=32), 15-18y (n=24)) were examined at two 1.5 T scanners (Siemens, GE) using a standard SSFP protocol. LV longitudinal, circumferential and radial strain and SR were measured using FTI (2D CPA MR©, TomTec Imaging System, Fulda). FTI was applied to standard cine-images in 3 short-axis, 4- and 3-chamber slices. The effects of age, gender, endo- and epicardial assessment, myocardial segments on strain and SR data were evaluated. Results: Global longitudinal and circumferential strains (strain rate) were -18.7±4.2% (1.6±0.4) and -25.5±6.5% (2.1±0.8), respectively with higher values being observed at basis than at apex. Radial strain was 21.7±10.3% (-2.1±0.5) with a decrease towards the apex. Strain and SR measurements varied between endo- and epicardial assessment also, with regional differences (apical versus middle and basal), but not with age or gender. Strains measured on data acquired with 2 MRI scanners had good correlations. Inter- and intra-observer variability were low (< 10%). Conclusions: For the first time normal FTI values of LV function in a large cohort of healthy children were provided. FTI offers additional data about regional and global cardiac function, using routinely acquired sequences using standard orientations.