Quantitative comparison of myocardial fiber structure between mice, rabbit, and sheep using diffusion tensor cardiovascu
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RESEARCH
Open Access
Quantitative comparison of myocardial fiber structure between mice, rabbit, and sheep using diffusion tensor cardiovascular magnetic resonance Lindsey J Healy1*, Yi Jiang2 and Edward W Hsu1
Abstract Background: Accurate interpretations of cardiac functions require precise structural models of the myocardium, but the latter is not available always and for all species. Although scaling or substitution of myocardial fiber information from alternate species has been used in cardiac functional modeling, the validity of such practice has not been tested. Methods: Fixed mouse (n = 10), rabbit (n = 6), and sheep (n = 5) hearts underwent diffusion tensor imaging (DTI). The myocardial structures in terms of the left ventricular fiber orientation helix angle index were quantitatively compared between the mouse rabbit and sheep hearts. Results: The results show that significant fiber structural differences exist between any two of the three species. Specifically, the subepicardial fiber orientation, and the transmural range and linearity of fiber helix angles are significantly different between the mouse and either rabbit or sheep. Additionally, a significant difference was found between the transmural helix angle range between the rabbit and sheep. Across different circumferential regions of the heart, the fiber orientation was not found to be significantly different. Conclusions: The current study indicates that myocardial structural differences exist between different size hearts. An immediate implication of the present findings for myocardial structural or functional modeling studies is that caution must be exercised when extrapolating myocardial structures from one species to another.
Background Computational studies are increasingly used to help interpret empirical measurements or to investigate functions of the body beyond experimental limitations. Because structures of the myocardium such as the fiber orientation play a deterministic role in its material properties and functional behaviours, accurate simulations of cardiac functions require precise anatomical models of the myocardium. Anatomy-based models of the myocardium have been used in computational studies of both electrophysiology [1,2] and mechanics [3-5] of the heart. In electrophysiological studies, utilizing anisotropic fiber orientation information has led to improved predictions * Correspondence: [email protected] 1 Department of Bioengineering, University of Utah, Salt Lake City, Utah, USA Full list of author information is available at the end of the article
of the electrical activity in the heart [2,6]. Similarly, incorporation of fiber structure into mechanical models has helped better explain the structure-function relationships [7,8]. Despite the significance of the information, measuring myocardial fiber orientation can be difficult, the key challenges being the small size (notably for the mouse) and availability of specimens (for humans). Tissue structures including myocardial fiber orientations are conventionally measu
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