A Methodology for Accessing the Local Arrangement of the Sheetlets that Make up the Extracellular Heart Tissue.

The sheetlet angle is a biomarker that can describe the local arrangement of the sheetlets making the heart wall tissue. It could be of major interest for the analysis of cardiac function. In this preliminary study, we use the skeleton method to measure the local sheetlet angle in two human left ventricular transparietal tissue samples. The samples were imaged using synchrotron X-rays phase contrast micro-tomography and reconstructed in 3D with isotropic voxels of 3.5 μ m edges. We extract the skeleton from each sheetlet. Next, we scan the skeleton, voxel by voxel, performing principal component analysis (PCA) in a sliding cubic working window (WW) of 112 μ m edges. The tertiary eigenvector of the PCA provides the sheetlet angle, step by step, along the skeleton. We show that the proposed methodology is able to provide the transmural distribution of sheetlets angle at a scale of 112 μ m and locally to investigate the spatial evolution of the angle along the sheetlets. We compare the results obtained at a larger scale with the Fourier-based method.