title: Improved cardiac tagging resolution at ultra-high magnetic field elucidates transmural differences in principal strain in the mouse heart and reduced stretch in dilated cardiomyopathy.
abstract: Cardiac tagging resolution for regional principal strains E1 and E2 has been a limiting factor for the study of dilated mouse hearts, in which the left ventricle (LV) wall thickness can drop to below 1 mm. Therefore, high resolution tagging was performed at 14.1 T to enable transmural principal strain measurements across the LV wall of normal mouse hearts and average principal strains in thinned LV walls of a transgenic mouse (PKCepsilon TG) that develops dilated LV. A modified DANTE tagging and fast gradient imaging method produced a tagging grid dimension of 0.33 x 0.33 mm and line thickness under 0.1 mm. In normal mice, average E1 strain in the epicardium was significantly higher than the endocardial E1 (epi = 0.22 +/- 0.10; endo = 0.13 +/- 0.07, p < 0.05), while magnitude of average endocardial E2 was greater than in the epicardium (endo = -0.12 +/- 0.03, epi = -0.08 +/- 0.03; p < 0.001). E1 strain averaged over four segments was reduced in dilated hearts compared to controls (PKCepsilon TG = 0.14 +/- 0.02; control = 0.18 +/- 0.02, p < 0.01), with specific reductions in septal (33%) and lateral (31%, p < 0.01) segments. E2 strain was similar between dilated and control hearts at -0.11 +/- 0.01. Thus, improved tagging resolution demonstrates that stretch (E1), but not compression strains (E2), are reduced as a result of significant LV wall thinning in a mouse model of dilated cardiomyopathy.
authors: Program in Integrative Cardiac Metabolism, Center for Cardiovascular Research, University of Illinois at Chicago College of Medicine, Chicago, IL 60612, USA.
authors: Janusz H
authors: JH
authors: Hankiewicz
authors: E Douglas
authors: ED
authors: Lewandowski
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002311:Cardiomyopathy, Dilated / Q000503:physiopathology*; D004195:Disease Models, Animal; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008822:Mice, Transgenic