Transcript Historical influence to MRI

Magnetic Resonance
Imaging
MRI
Objectives:
 Discuss the MRI historical development, and to
know the significant person who discovered MRI.
 MRI discovery time line
 Persons involved
 What are their Contributions
 Overview of the basic principle of MRI
 Advantages of MRI over other Modalities
 Different Components of MRI
MRI Topic 1
Democritus
 In early 400B.C
 First to theorize that all matter consist of both
invisible and indivisible particles
Greeks
 Also noted and observed that a piece of
amber, when rubbed by fur, would attract
specific particles or object.
AMBER
MAGNESIA
 TURKEY
 City of Magnesia is the origin of the term
magnetism.
 Observed that when certain rock formation were
spun on their axes, they always and immediately
returned to their original orientation. These
magnetize structure, which are called lodestone.
LODESTONE
BAPTISTE-JOSEPH FOURIER
 Introduced a
complex
mathematics that
translate raw MR
signals into spatial
location while
serving emperor
napoleon of France
Hans Christian Oersted
 1819 discovered that electricity produces
magnetism when he noted that a compass
needle would deflect in the presence of an
electric charge.
Michael Faraday
 Stated and
successfully
demonstrated that
electricity can
produce magnetism.
Michael Faraday
 Calculated the velocity
and propagation of
electromagnetic waves
and predicted the
existence of other
waves in addition to
the ultraviolet and
infrared regions.
Sir James Clerk Maxwell
 In 1860 discovered
magnetic lines of
force could be
mathematically
expressed.
Heinrich Hertz of Germany
 In 1868 discovered
that invisible
electromagnetic
wave do exist and
that all
electromagnetic
waves are
identifiable by their
characteristic wave
frequency values.
Heinrich Hertz of Germany
 Electromagnetic
spectrum – the
categorical
arrangement of the
wave energies
corresponding to
their properties,
began to take form.
Wilhelm Conrad Roentgen
 Nov. 8, 1895 discovered the x-ray
Marie Curie
 In 1896 discovered the gamma rays by
experimenting on radioactive phosphors.
Their discoveries soon demonstrated that high
frequency wave energies were identifiable,
detectable, measurable and often biologically
damaging.
Post WORLD WAR II
 Some of the technology advances associated
with the world war 2 laid the groundwork for
utilizing sonograpghy (submarine detection)
and nuclear medicine (atomic energy) for
human.
Felix Bloch & Edward Purcell
 1946
 Explore the mystery of atom.
 They noted that when a test tube sample of
a pure substance was magnetically
energized and RF bombarded the excited
atoms themselves would respond by singing
their own atomic ‘’tune’’.
Felix Bloch & Edward Purcell
Felix bloch & edward purcell
 These tune signal were detected and
recorded into spectroscopic images,
corresponding to their frequency values.
 Virtually overnight Nuclear Magnetic
Resonance (NMR). The prelude to MRI, was
about to be born.
Felix bloch & edward purcell
 Bloch and Purcell were recipients of the Novel
Price in 1952 for their major contribution in
uniquely discovering and implementing the
use of atomic energy for analytical purposes.
END…
(BASIC PRINCIPLES) MRI TOPIC 2
MRI
 Originally called Nuclear Magnetic Resonance
or NMR.
 “Nuclear” indicated that the radioactive
atomic nucleus played an important role.
Basic Principle of MR
 A certain atomic nuclei, if placed in a
magnetic field, can be stimulated by
(absorb energy from) radio waves of the
correct frequency.
 Following this stimulation, the nuclei
release the extra absorbed energy by
transmitting radiowaves (the MR) signal,
which can be received by an antenna and
analyzed.
Behavior of a hydrogen nuclei
Advantages of MRI over other
Modalities
1. Contrast Resolution
2. Multi-Planar Imaging
3. No Radiation
CONTRAST RESOLUTION
 Principal advantage of MRI

Allows visualization of low- density
objects with similar soft tissue
characteristics, such as liver- spleen
or white matter – gray matter

It is a function of several intrinsic
properties of the tissue being
imaged.
MRI HAS HIGH CONTRAST RESOLUTION
Multi-Planar Imaging
 Ability to obtain direct transverse, sagittal,
coronal and oblique plane images
CORONAL VIEW
SAGITTAL VIEW
TRANSVERSE
VIEW
TRUE OR
FALSE?
NO Radiation
 MRI does not use Ionizing radiation
 MRI uses RF electromagnetic radiation
and magnetic fields, which do not cause
ionization and therefore do not have
associated potentially harmful effects of
ionizing radiation
MRI Hardware
3 main components:
1. Gantry
2. Computer
3. Operating Console
Gantry
 Is the large, usually cylindrical device that
accommodates the patient during imaging
 MRI gantry does not have moving parts-
everything is electronically controlled
 The patient aperture is usually 50- 60 cm in
diameter
WHERE IS THE GANTRY??
RF COILS
 RF coils which is called the RF probe,
surrounds the patient in this aperture
 Gradient coils, shim coils, and in the case of an
electromagnetic, primary coils all surrounds
the RF probe to produce the static magnetic
field
RF COILS
BODY COIL
HEAD COIL
Computer
 Similar to CT, only faster and bigger
 During MRI examination, more data are
collected and the computations required
are longer and more difficult than the CT
Operating Console
 MRI patient does not move
 MRI console has RF controls rather than kVp,
mA and scan time controls
MRI OPERATING CONSOLE
MRI Overview
The hydrogen nuclei in the Patient- protons-
behave like tiny magnets
Hydrogen makes up 80 % of all atoms found
in the human body, making hydrogen
extremely useful for MRI.
Because Hydrogen is a single- charge spinning
nucleons, the hydrogen nucleus exhibit
relatively strong magnetism
END..