Assessment of the sheetlet thickness in human left ventricular free wall samples using X-ray phase-contrast microtomography

Abstract

Background and Objective:

In the left ventricular (LV) wall, most cardiomyocytes are organized into sheetlets. A good knowledge of the sheetlet arrangement is crucial for understanding ventricular functions.

Methods:

In this paper, we introduced a distance-field method to measure the evolution of the thickness of local sheetlets and cleavage planes (CPs) in the laminar structure regions of five human LV free wall transmural samples. The data were acquired using the European Synchrotron Radiation Facility. The high-resolution synchrotron radiation phase-contrast micro-tomography (SR-PCT) imaging with an isotropic spatial resolution of $3.5\times 3.5\times 3.5\mu m^3$ allows for a clear observation of the sheetlet arrangement. First, we flattened the samples using Difference of Gaussians (DoG). Secondly, we extracted the sheetlets and CPs using connex filters with different sizes. Then, we generated the laminar structure simulation models to validate distance-field method. Last, we measured the thickness of local CPs and sheetlets by calculating their Chamfer-distance fields.

Results:

Sheetlets are thinner and CPs are thicker in the regions with flat sheetlet arrangements; CPs are thicker around blood vessels; and sheetlets are thinner around the intersection region of two sheetlet populations. This regional variation relates to the location of samples in the LV wall, the sheetlet organization manner, and the local myocardial architecture.

Conclusions:

The results demonstrate that the distribution of the thickness of sheetlets and CPs is regional, which provides morphology support for the future research about the myocardial mechanical function and the pathological mechanism of heart diseases.