International Journal of Biomedical Imaging 
Volume 2006 (2006), Article ID 45957, 15 pages
doi:10.1155/IJBI/2006/45957

Anisotropic Elastography for Local Passive Properties and Active Contractility of Myocardium from Dynamic Heart Imaging Sequence

Yi Liu,1,2 Ge Wang,1 and L. Z. Sun3

 1Center for X-Ray and Optical Tomography, Department of Radiology, The University of Iowa Hospitals and Clinics, Iowa City 52242, IA, USA
2Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, Indianapolis 46204, IN, USA
3Department of Civil and Environmental Engineering, University of California, Irvine 92697, CA, USA
Received 26 June 2006; Accepted 19 September 2006

Recommended by Seung Wook Lee

Abstract

Major heart diseases such as ischemia and hypertrophic myocardiopathy are accompanied with significant changes in the passive mechanical properties and active contractility of myocardium. Identification of these changes helps diagnose heart diseases, monitor therapy, and design surgery. A dynamic cardiac elastography (DCE) framework is developed to assess the anisotropic viscoelastic passive properties and active contractility of myocardial tissues, based on the chamber pressure and dynamic displacement measured with cardiac imaging techniques. A dynamic adjoint method is derived to enhance the numerical efficiency and stability of DCE. Model-based simulations are conducted using a numerical left ventricle (LV) phantom with an ischemic region. The passive material parameters of normal and ischemic tissues are identified during LV rapid/reduced filling and artery contraction, and those of active contractility are quantified during isovolumetric contraction and rapid/reduced ejection. It is found that quasistatic simplification in the previous cardiac elastography studies may yield inaccurate material parameters.