We propose to test a novel technique - the Generalized Anisotropic Inverse Mechanics (GAIM) method - for determination of tissue anisotropy as a function of position from a displacement image. The approach uses displacement data and a general linear elastic mechanical model for tissue to determine mechanical parameters at different positions by solving the inverse mechanics problem directly. The method partitions the domain into regions, and the components of the general linear elasticity tensor are assumed to be constant over each partition. We have tested GAIM on simulated data but need to perform studies on real data to assess its ability to generate useful information about ex vivo and in vivo tissues. In this exploratory project, we will test the hypothesis that GAIM can successfully provide distributed mechanical information about native and engineered tissue, as well as the secondary hypothesis that mechanical anisotropy correlates with structural anisotropy, the latter measured by other methods. If successful, the project will lay the groundwork for future development and implementation of the GAIM technique and thus lead to a new tool for biomechanical imaging. Mechanical properties of tissues are essential for proper function and may indicate injury or disease. The availability of a tool to study healthy vs. damaged tissue non-invasively, particularly during healing, would be a major aid to our ability to understand injury and healing in load-bearing tissues (e.g., heart valve, myocardium, tendon, ligament) and is thus highly relevant to public health.
We will explore a new biomechanical image analysis technique - the Generalized Anisotropic Inverse Mechanics (GAIM) method - to measure distributed, direction-dependent tissue properties based on displacement images generated. Unlike standard methods, GAIM calculates the anisotropy of the tissue as well as its stiffness, potentially allowing a new level of evaluation of injury, disease, and healing in highly structured tissues, in vitro and perhaps in vivo.
|Witzenburg, Colleen; Raghupathy, Ramesh; Kren, Stefan M et al. (2012) Mechanical changes in the rat right ventricle with decellularization. J Biomech 45:842-9|
|Raghupathy, Ramesh; Witzenburg, Colleen; Lake, Spencer P et al. (2011) Identification of regional mechanical anisotropy in soft tissue analogs. J Biomech Eng 133:091011|