Analysis of Cardiac Torsion with Strain Tensor

Abstract

The heart is important internal organs for the human body, and it is known by doing a very efficient systole-diastole movement. It is thought that the twist movement of the heart and the twist arrangement of cardiac muscle fiber influence to an efficient movement of the heart, so various studies are studied.

The Phase-Contrast method of MRI can measure the velocity distribution of the arbitrary direction, so we can obtain three-dimensional velocity field by measuring three or more times. The twist movement of the heart can be analyzed directly by using three-dimensional velocity field.

It is a problem that the decision of the center of rotation is necessary in case of the method of analysis that uses the rotating angle. In this research, we propose the method of analysis that doesn’t need the decision of the center of rotation by using the strain in micro region.

First, we calculated the trend of the direction of the maximum principal strain and the normal direction of the maximum shear plane of the numeric model. Next, we compared these directions of measurement data with ones of the numeric model. As a result, three results were obtained. 1: In the region with twist in section, the direction of the maximum principal strain shows the vertical direction. 2: In the region with twist between sections, the direction of the normal direction of the maximum shear plane shows the vertical direction. 3: From the time change of the ratio of the region of twist, we got the tendency that the influence of the twist between sections was strong at end systole, and one of the twist in section was strong at early systole and early diastole.