Biomedical Engineering Reference
In-Depth Information
Chapter 3
Advances in Magnetic Resonance Angiography
and Physical Principles
Rakesh Sharma
1
and Avdhesh Sharma
2
3.1 Introduction
In this chapter, we will discuss the physical principles of magnetic resonance
angiography (MRA). MRA may at first appear very complicated, but we shall try
to present the major concepts in the simplest form. The first part concentrates
on physical principles of flow magnetization and flow characteristics in human
vascular system. The later part is devoted to various magnetic resonance an-
giography techniques from the MRA physics as well as angiography technique
refinement points of view.
MRA is a technique for obtaining information on blood motion mainly in
the cardiovascular and cerebrovascular systems. Let us consider how motion
or flow in the vessels generates the angiographic effect for creating magnetic
resonance (MR) images.
3.1.1 Principles of Magnetization and Flow
The vascular system experiences motion of blood due to continuous flow of
blood inside. Precession frequency and gradient field vectors are related. These
vectors are represented as spin isochromats. The behavior of the moving spin
1
Department of Medicine, Columbia University, New York, NY 10032, USA
2
Electrical Engineering Department, Indian Institute of Technology, New Delhi 10016,
India
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