An Automated System for 3D Segmentation of CT Angiograms - Visual Computing: Scientific Visualization and Imaging Systems - page 95

List of Abbreviations

CTA Computed tomography angiography

CAD Coronary artery disease

CT Computed tomography

EM Expectation maximisation

GMM Gaussian mixture model

LAD Left anterior descending

LCA Left coronary artery

LCX Left circumflex

LM Left main coronary

RCA Right coronary artery

WHO World Health Organization

5.1 Introduction

According to the most recent statistics by the World Health Organization (WHO),
coronary artery disease (CAD) is one of the most prevalent causes of death in the
world. Approximately 17 millions people are killed due to one or more types of
CAD every year worldwide [ 1 ]. Atherosclerosis is a common cause of CAD,
where plaque builds up on the insides of arteries. Plaques are typically made up of
fat, cholesterol, calcium and other substances found in the blood. If left untreated,
it will harden and narrow the arteries over a period of years. As a consequence, the
flow of oxygen-rich blood to organs and other parts of body will be reduced thus
leading to serious problems, including myocardial/cerebral infarction, or even
death. Figure 5.1 shows a comparison before and after plaque builds up within a
blood vessel.
Coronary arteries are the network of blood vessels which supply blood to the
myocardium. CAD occurs when the coronaries are occluded and become con-
stricted, which makes the heart become starved for oxygen and other nutrients and
eventually stop beating. As illustrated in Fig. 5.2 , the arterial tree basically con-
sists of two main branches, namely the Left Coronary Artery (LCA) and Right
Coronary Artery (RCA), which arise from the root of the aorta, near the top of the
heart. In LCA, the initial segment between the aorta and the first bifurcation is
called the left main (LM) coronary. The LM typically branches into the left
anterior descending (LAD) and the left circumflex (LCX) arteries. On the other
hand, the RCA normally originates from the right coronary cusp and travels to the
posterior interventricular branch. In 85 % of cases, the RCA is the dominant vessel
and supplies the posterior descending branch which travels in the PIV groove.
However, the exact anatomy of the coronary arteries could exhibit large differ-
ences from individual to individual [ 2 ].