Visualization techniques for the assessment of the motion and the deformation of the left ventricular wall throughout the cardiac cycle

We will present here mathematical concepts, computer methods, and visualization techniques which have been developed to improve diagnosis in the extraordinarily important clinical field of coronary artery disease. In this diagnostic domain, a fair assessment of the contractility and the motion of the heart plays a pivotal role, whereby the regional contractility of the left ventricle is at the centre of interest. Usually, this myocardial function is quantitatively only assessed by measuring the ejection fraction which is merely a global characteristic of disease and does not describe the regional motion and contractility. However, in the field of diagnosis and therapy of coronary artery disease, it would be highly meaningful to acquire a fair knowledge of the regional heart wall motion, since important processes of coronary artery disease, such as hibernation and infarction, manifest themselves in regional abnormalities of heart motion, especially of the motion of the left ventricle. Regional motion analyses will thus enable cardiologists to delve into greater detail in carrying out their diagnostic procedures. Unfortunately, the accuracy of all currently available methods for the acquisition and analysis of the regional heart wall motion is rather limited. For this reason, we developed a sufficiently accurate technique for tracking and analyzing the regional motion of the outer surface of the myocardium. In Section 2 of this paper, we will give an overview of our approach to the acquisition and representation of the geometry of the outer surface of the left ventricle in the course of the cardiac cycle. We will then deal with the quantitative analysis of the deformation of the left ventricle by calculating and representing the time-varying surface strain in terms of tensor quantities. Our calculations of the geometry and the deformation resulted in a wealth of numerical data. To be of any value for cardiologists, these data need to be visualized in an appropriate manner. In Section 3, we will show how to solve these analysis and visualization problems.