Towards myocardial contraction force image reconstruction for heart disease assessment and intervention planning

© 2015 SPIE. It is clinically vital to devise a technique to evaluate regional functionality of the myocardium in order to determine the extent and intensity of local damage to the cardiac tissue caused by ischemic injuries. Such a technique can potentially enable cardiologists to discriminate between reversible and irreversible ischemic injuries and to devise appropriate revascularization therapy in case of reversible lesions. The technique is founded on the premise that sufficient contraction force generated by the cardiac tissue can be regarded as a direct and reliable criterion for regional analysis of tissue healthy functionality. To this end, a number of imaging techniques have been developed and, to our knowledge, none of them assess regional cardiac functionality based on a straightforward mechanical measure such as local cardiac contraction forces. As such, a novel imaging technique is being developed on the basis of quantification and visualisation of local myocardial contraction forces. In this technique, cardiac contraction force distribution is attained through solving an inverse problem within an optimization framework which uses iterative forward mechanical modelling of the myocardium. Hence, a forward mechanical model of the myocardium which is computationally efficient, robust, and adaptable to diverse pathophysiological conditions is necessary for this development. As such, this paper is geared towards developing a novel mechanical model of the healthy and pathological myocardium which considers all aspects of the myocardial mechanics including hyperelasticity, anisotropy, and active contraction force. In this investigation, two major parts, including background tissue and reinforcement bars (fibers) have been considered for modelling the myocardium. The model was implemented using finite element (FE) approach and demonstrated very good performance in simulating normal and infarcted left ventricle (LV) contractile function

Comparative biomechanical study of using decellularized human adipose tissues for post-mastectomy and post-lumpectomy breast reconstruction

© 2015 Elsevier Ltd. Developing suitable biomaterials for post-mastectomy or post-lumpectomy breast reconstruction is highly important. This study is aimed at evaluating biomechanical suitability of decellularized adipose tissue (DAT) for this purpose. The study involves computational experiments for evaluating deformation of the breast reconstructed using DAT under loading conditions pertaining to two common body position changes of prone-to-supine and prone-to-upright. This was conducted using nonlinear finite element models where the breast geometry was obtained from MRI image of a female breast. The experiments were performed using DAT sourced from various adipose tissue depots in comparison to natural adipose tissue. Data obtained from the conducted experiments showed no contour defects with various DAT materials for simulated post-mastectomy or post-lumpectomy breast reconstruction under the loading conditions. They also demonstrated that a breast reconstructed using DAT derived from the breast or subcutaneous abdominal depots exhibit significantly closer deformation, both qualitatively and quantitatively, to that of a normal breast under the same loading conditions. Similarity of DAT deformation to that of natural breast tissue in post-surgery breast reconstruction was assessed using nonlinear finite element analysis. Our results provide evidence that DAT derived from subcutaneous abdominal and breast depots yield more analogous deformation pattern to the natural tissue in post-mastectomy breast reconstruction applications. This is quite encouraging, as breast and subcutaneous adipose tissue can be readily obtained in large quantities from breast or abdominal lipo-reduction surgery procedures. Furthermore, in post-lumpectomy cases all DAT samples used in this research showed similar deformation, and thus are suitable as breast tissue substituents