Model-Based Analysis of Myocardial Strain Data acquired by Tissue

Objective: Tissue Doppler Imaging (TDI) is commonly used to evaluate regional ventricular contraction 26 properties through the analysis of myocardial strain. During the clinical examination, a set of strain signals is 27 acquired concurrently at different locations. However, the joint interpretation of these signals remains 28 difficult. This paper proposes a model-based approach in order to assist the clinician in making an analysis of 29 myocardial strain. 30 Methods and material: The proposed method couples a model of the left ventricle, which takes into account 31 cardiac electrical, mechanical and hydraulic activities with an adapted identification algorithm, in order to 32 obtain patient-specific model representations. The proposed model presents a tissue-level resolution, adapted 33 to TDI strain analysis. The method is applied in order to reproduce TDI strain signals acquired from two 34 healthy subjects and a patient presenting with Dilated Cardiomyopathy (DCM). 35 Results: The comparison between simulated and experimental strains for the three subjects reflects a 36 satisfying adaptation of the model on different strain morphologies. The mean error between real and 37 synthesized signals is equal to 2.34% and 2.09%, for the two healthy subjects and 1.30% for the patient 38 suffering from DCM. Identified parameters show significant electrical conduction and mechanical activation 39 delays for the pathologic case and have shown to be useful for the localization of the failing myocardial 40 segments, which are situated on the anterior and lateral walls of the ventricular base. 41 Conclusion: The present study shows the feasibility of a model-based method for the analysis of TDI strain 42 signals. The identification of delayed segments in the pathologic case produces encouraging results and may 43 represent a way to better utilize the information included in strain signals and to improve the therapy 44 assistance. 45