Abstract
Alterations of Young’s modulus (YM) and Poisson’s ratio (PR) in biological tissues are often early indicators of the onset of pathological conditions. Knowledge of these parameters has been proven to be of great clinical significance for the diagnosis, prognosis and treatment of cancers. Currently, however, there are no non-invasive modalities that can be used to image and quantify these parameters in vivo without assuming incompressibility of the tissue, an assumption that is rarely justified in human tissues. In this paper, we developed a new method to simultaneously reconstruct YM and PR of a tumor and of its surrounding tissues based on the assumptions of axisymmetry and ellipsoidal-shape inclusion. This new, non-invasive method allows the generation of high spatial resolution YM and PR maps from axial and lateral strain data obtained via ultrasound elastography. The method was validated using finite element (FE) simulations and controlled experiments performed on phantoms with known mechanical properties. The clinical feasibility of the developed method was demonstrated in an orthotopic mouse model of breast cancer. Our results demonstrate that the proposed technique can estimate the YM and PR of spherical inclusions with accuracy higher than 99% and with accuracy higher than 90% in inclusions of different geometries and under various clinically relevant boundary conditions.
Highlights
Alterations of Young’s modulus (YM) and Poisson’s ratio (PR) in biological tissues are often early indicators of the onset of pathological conditions
The YM distributions in simulated samples with different mechanical properties reconstructed using the proposed method were compared with results obtained using two previously proposed 3D reconstruction methods, which here are referred to as “3DB”20 and “3DS”6
It should be noted that our method reconstructs the YM and PR on a pixel-by-pixel basis, and we have proven that the method can still provide highly accurate YM and PR estimates even in the case of heterogeneous YM and PR distributions (Fig. 1(A4))
Summary
Alterations of Young’s modulus (YM) and Poisson’s ratio (PR) in biological tissues are often early indicators of the onset of pathological conditions Knowledge of these parameters has been proven to be of great clinical significance for the diagnosis, prognosis and treatment of cancers. We developed a new method to simultaneously reconstruct YM and PR of a tumor and of its surrounding tissues based on the assumptions of axisymmetry and ellipsoidalshape inclusion This new, non-invasive method allows the generation of high spatial resolution YM and PR maps from axial and lateral strain data obtained via ultrasound elastography. Determination of heterogeneous distribution of YM inside the inclusion and background is another challenge[24] Most of these methods fail to reconstruct the YM accurately in case of non uniform axial compression, which occurs frequently in clinical elastography experiments
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