Introduction
MRI, Magnetic Resonance Imaging, also known as Nuclear
Magnetic Resonance Imaging (NMRI), and Magnetic Resonance
Tomography (MRT). The MRI scanner is relatively a new device of
medical imaging, non-invasive, that demonstrates the interior of
the human body. The roots of the MRI technology are based on a
principle first discovered in the late 1930s - magnetic resonance
(MR).
One of the first applications of this principle was a device called
Nuclear Magnetic Resonance (NMR). NMR is used to identify the
atomic and molecular structure of chemicals. The MRI scanner,
the most popular, commercial and known use of the Magnetic
Resonance Principal, is a development of the NMR device that
made it possible to get a 3D accurate picture of internal organs in
the body. These pictures have significantly improved diagnostic
ability and are helping surgeons to understand the anatomy and
pathology better before surgery.
The Magnetic Resonance Principal is the base of many
implementations other than NMR and MRI, some of them based
on nuclear magnetic resonance, and some of them based on
electronic electron resonance (Electron Paramagnetic Resonance,
EPR), such as accurate atomic clocks, Maser (The equivalent of
the laser, only in microwaves), methods of characterizing defects
in materials and more. The research today is implying that in the
future this principle can help develop other implementation in
various fields.
This book is divided into five chapters that describe the magnetic
resonance technology as a whole and MRI in particular.
Chapter I – The History of MRI. In this chapter, we will briefly
describe the sequence of events from the discovery of the NMR,
through the invention of the CT, to the invention of the MRI, and
get familiar with the stories of the people who contributed to these
discoveries. At the end of the chapter, we will discuss the
controversy that broke out when the Nobel Prize was not awarded
to one of the founders of the idea- a prominent figure in this fieldRaymond Vahan Damadian.
Chapter II – Basic Concepts. In this chapter, we will present the
basic concepts in the physics of magnetic resonance, in order to
lay the foundations for understanding the following chapters, even
for those who have no background in physics.
We will examine the term Nuclear Magnetic Resonance Imaging
and explain each of the words in a separate section. In the first
section we describe the structure of the atom; In the second
section we will focus on the phenomenon of electromagnetism and
its expressions at the various levels in the MRI scanner; In the
third section we explain the phenomenon of resonance in general
and the magnetic resonance in particular; In the fourth section we
will deal with the imaging itself, the elements of image creation and
the process in which the digital data passes through the
computerized systems of the hospitals.
Chapter III – The Physics behind the MRI. This is the central
chapter of the book. Here, we will learn the physical principals of
Magnetic Resonance as its being expressed in the MRI Scanner.
We will demonstrate gradually, methodically and clearly the
physical factors of magnetic resonance. We will describe the
Zeeman Effect, the proton precession and the radio pulse at the
Larmor frequency. We will also describe the decay processes and
explain the terms- T1, T2, PD, TR, TE, and TI. We will see how a
signal is generated and present the types of pulse sequences,
including fast sequences, such as gradient-echo sequences. We
will describe the role of the gradients during the MRI scans, how to
connect the signal to the location of the scan area, the role of
gadolinium, coil types, Fourier transform, MRI artifacts, how NMR
works and many other subjects.
Chapter IV – MRI and its position in the world of imaging. In
this chapter, we will present the way in which MRI fits into the
fabric of today's imaging devices.
In the first section of this chapter, we will review in detail and
explain all the imaging techniques currently available: X-ray, CT,
ultrasound, nuclear medicine, PET scans, SPECT scans and their
combinations with CT and MRI (hybrid imaging). Each of the
imaging methods is described in detail, regarding its advantages
and disadvantages, and indications for its use.
The second section will focus on indications for an MRI scanning
and the advantages and disadvantages of the use of MRI imaging
in relation to other imaging methods. We will also discuss the
dangers of MRI and precautions to be taken when using it.
In the third section we will describe the types of MRI scanners
available today: open MRI vs closed MRI and their differences
between them, a small MRI for operating rooms, MRI for breast
scanning, special MRI for children, and others.
In the fourth section, we will review Special MRI exams that have
developed over the years, including MRA (MRI of the blood
vessels), MRM (MRI of the breast), MRCP (MRI of bile ducts),
DMRI (diffusion MRI), profusion MRI, MRS (MRI spectroscopy),
MRE (MRI of the colon), CVMRI (MRI of the heart and blood
vessels), MRU (MRI of the urinary tract), MRI prostate, and more.
The fifth and final section of this chapter reviews the applications
of MRI, for example fMRI (functional MRI), DTI (imaging of the
brain's nerve), FUS (use of focused ultrasound with MRI
guidance), and more. We will also review the use of magnetic
resonance technology in non-medical applications. for example,
the use of magnetic resonance imaging for oil pipelines, for nondestructive testing of rocks, wood, and other crops.
Chapter V - What Does the Future Hold? In this chapter, we will
describe the future of the MRI revolution. We will review the
applications and technology improvements, currently under
research and development, in the study of magnetic resonance in
general, and in the diagnostic MRI and fMRI fields in particular. All
of these are based on interviews with scientists and developers
from start-up companies that specialize in the recent subject
research conducted in the world today.
The first section of the chapter describes the future of the study of
magnetic resonance and the challenges faced by researchers in
this field.
The second section describes the attempts to improve the
magnetic resonance technology, such as getting rid of the giant
magnet by creating a superconductor at room temperature.
In the third section, we will focus on improvements in existing MRI
scanners, such as General Electric's new Silenz protocol designed
to make the MRI test much quieter, and the European INUMAC
project, which is trying to develop a scanner with 11.75 Tesla.
In the fourth section of this chapter, we will describe the latest
news in the development of MRI exams, contrast materials, and
MRI software, and in the fifth section we will describe amazing
future applications of fMRI, such as lie detectors, robot activation
with the mind and communication with people whose condition is
defined as vegetative.
At the end of the book, you will find an extensive glossary of
concepts, presented in the book's chapters, a bibliography which
allows you access the relevant literature and expand the
knowledge in the fields in which the book deals, and an index.
All we have to do is tighten our seatbelts and take off!