Transcript MAGNETIC RESONANCE IMAGING

MAGNETIC RESONANCE
IMAGING
2003 Noble Prize Laureates in
Physiology or Medicine
Paul C. Lauterbur and Peter Mansfield
Noble Prize
6 October 2003
Press Release
The Nobel Assembly at Karolinska Institute
has today decided to award The Nobel
Prize in Physiology or Medicine for 2003
jointly to
Paul C. Lauterbur and Peter Mansfield
for their discoveries concerning
“magnetic resonance imaging”
“for their discoveries concerning magnetic
resonance imaging”
Paul C. Lauterbur
½ of the prize USA
University of Illinois
Urbana, IL, USA.
b. 1929
Peter Mansfield
½ of the prize United Kindom
University of Notingham
United Kingdom.
b. 1933
Paul C. Lauterbur
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born May 6, 1929 in Sidney, Ohio, USA.
1951 B.S. in Chemistry, Case Institute of
Technology, Cleveland
1962 Ph.D. in Chemistry, University of
Pittsburgh, Pennsylvania
1969-85 Professor of Chemistry, Radiology,
New York University at Stony Brook
1985-90 Professor, University of Illinois,
College of Medicine at Chicago
1985-Professor and Director, Biomedical
Magnetic Resonance Laboratory, University of
Illinois, College of Medicine at Urbana, IL.
Peter Mansfield
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born October 9, 1933.
1959 B.Sc. Queen Mary College, University of
London
1962 Ph.D. Physics, University of London
1962-64 Research Associate, University of
Illinois.
1964 Lecturer, University of Nottingham.
1968 Senior Lecturer, University of
Nottingham.
1972-73 Senior Visitor, Max Planck Institut
für Medizinische Forschung, Heidelberg
1979- Professor, University of Nottingham.
History of MRI
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Late 1800’s
November 5, 1895. William Roentgen
discovered X-rays.
Roentgen discovered that:
X-rays travel in straight lines,
could not be refracted or reflected
did not respond to magnetic or electric field.
February, 1896, X-rays were being used
clinically in the United States.
History of MRI
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In the 1930’s, a physics phenomenon was
discovered, called nuclear magnetic resonance
or NMR.
Felix Bloch, working at Stanford University,
and Edward Purcell, from Harvard University,
discovered NMR.
In NMR nuclei were placed in a magnetic field,
they absorbed energy in the radiofrequency
range of the electromagnetic spectrum, and reemitted this energy when the nuclei transferred
to their original state.
History of MRI
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This phenomenon was termed NMR as
follows:
"Nuclear" as only the nuclei of certain atoms
reacted in that way;
"Magnetic" as a magnetic field was required;
"Resonance" because of the direct frequency
dependence of the magnetic and
radiofrequency fields.
History of MRI
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For their discovery of NMR Bloch and Purcell
were awarded the Nobel Prize for Physics in
1952.
Use of NMR to investigate the chemical
composition and physical structure of matter.
Relaxation times, T1 and T2.
T1: Time taken by nuclei in test samples to
return to their natural alignment
T2: Duration of the magnetic signal from the
sample.
History of MRI
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In 1970s Raymond Damadian, proposed that
each tissue in the body has a different
relaxation time, but cancerous tissue has an
abnormally long relaxation time.
He believed that the NMR could be used as an
“external probe for the internal detection of
cancer”
Damadian presented first commercial NMR
scanner at the annual meeting of the
American Roentgen Ray Society in 1980.
History of MRI
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Paul C. Lauterbur determined the origin of
the radio waves by analysis of their
characteristics.
Discovered the possibility to create a twodimensional picture by introducing gradients
in the magnetic field.
In 1972, obtained the first MRI.
History of MRI
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Pater Mansfield further developed the
utilization of gradients in the magnetic field.
Signals could be mathematically analyzed.
Showed how extremely fast imaging could be
achievable.
In 1976, he and his colleagues created the first
MRI of a human body part, a finger.
What is an MRI?
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Magnetic Resonance Imaging (MRI) :safe and
noninvasive test.
Diagnostic technique :uses strong magnetic
field and pulses of radio waves.
Produces pictures of structures inside the
body.
Images :slices of an organ or part of body.
MRI’s computer: 3-D images.
How it works?
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Body :strong magnetic field.
Machine uses :strong magnetic field and
pulses of radio waves.
Machine creates an image :how hydrogen
atoms react.
Usually images are created as single slices of
organs or structures.
MRI computer combine them to give a 3 D
image.
Using Our Body’s Magnets
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Because of predictions from physics and
math we know there are very weak
magnets in all living tissues
These magnets are atoms with unpaired
numbers of protons and electrons like
hydrogen 1H
There are billions and billions of
hydrogens in your body
Using Our Body’s Magnets
H do not have a matched pair of neutrons
and protons
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When atomic nuclei do have perfectly
matched neutrons and protons, these always
arrange in pairs and rotate in opposite
directions to one another
With 1H, there is no match and there is a
nuclear spin and slight + charge
Using Our Body’s Magnets
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One way is to stick these very weakly
magnetic tissues in a gigantic, strong
MAGNET and see what happens!!!!!!
This is the principle of Magnetic Resonance
Imaging, (MRI) used in research and
diagnostic radiology today!!!!!!!!!
A moving electric charge produces a magnetic
field
Protons have a positive charge
Protons spin
Protons produce a small magnetic field
No external field…
Randomly aligned
External field…
Aligned with field
Some protons align against the
field…
Some protons align with the
field…
Protons continually oscillate – always a slight excess aligning
with field
Aligning with field – slightly lower energy state
Protons Wobble
Spinning protons wobble about the
axis of the external field
Frequency of precession = Resonance Frequency
Depends on strength of magnetic field
RF Pulse
Apply RF pulse at resonance frequency
Protons absorb energy
Protons ‘jump’ to a
higher state
What goes up…
…must come down
Energy is re-transmitted as RF signal
Summary
MRI Signal
MRI Hardware
Control Room
Scanner
Console
MRI Hardware
Scanner
Liquid Helium Cooled
1.5 Tesla Solenoid Magnet
Radiofrequency
Transmitter/Recieiver
Coil
Patient Platform
MRI of the Brain - Sagittal
T1 Contrast
TE = 14 ms
TR = 400 ms
T2 Contrast
TE = 100 ms
TR = 1500 ms
Proton Density
TE = 14 ms
TR = 1500 ms
MRI of the Brain - Axial
T1 Contrast
TE = 14 ms
TR = 400 ms
T2 Contrast
TE = 100 ms
TR = 1500 ms
Proton Density
TE = 14 ms
TR = 1500 ms
T1 and T2 Weighting
Brain - Axial Multislice T1
Contrast in MRI
T1
T2
Gadolinium
The Whole Brain Atlas: http://www.med.harvard.edu/AANLIB/
Brain Tumor
Laser Polarized Gas Lung
Imaging
Chronic Obsructive Pulmonary Disease
Healthy Volunteer
Advantages of MRI
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Diagnosing multiple sclerosis (MS)
Diagnosing tumors of the pituitary gland
and brain.
Diagnosing infections in the brain, spine or
joints
Visualizing torn ligaments in the wrist,
knee and ankle
Advantages of MRI
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Visualizing shoulder injuries
Diagnosing tendonitis
Evaluating masses in the soft tissues of the
body
Evaluating bone tumors, cysts and
bulging or herniated discs in the spine
Diagnosing strokes in their earliest stages.
Disadvantages of MRI
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Not for everybody.
machine makes a tremendous amount of
noise.
require patients to hold very still for extended
periods of time.
Orthopedic hardware (screws, plates, artificial
joints) in the area of a scan can cause severe
artifacts (distortions) on the images.
very expensive.
Future of MRI
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Very small scanners.
Functional brain mapping.
Ventilation dynamics of the lungs through the
use of hyperpolarized helium-3 gas.
Image strokes in their earliest stages.
Limitless future
Laser Polarized Xenon MRI
Functional Brain Imaging
Map of Blood Flow in the Rat Brain
Functional Brain Imaging
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Blood Oxygenation Affects Contrast
Metabolism uses oxygen
Contrast Reveals regions of oxygen
consumption
University of Minnesota
http://www.cmrr.drad.umn.edu/highlight/index.html
Laser Polarized Gas Images
University of Virginia
Sources used:
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http://www.nobel.se/medicine/laureate
s/2003/
http://inventors.about.com/
http://www.bae.ncsu.edu/
http://www.isbe.man.ac.uk/
www.cmrr.drad.umn.edu/
Slides provided by Dr. Vankley.