2. TABLE OF CONTENTS
1. INTRODUCTION
2. HISTORY
3. USES
4. COMPONENTS
5. PRINCIPLE
6. HOW DOES IT WORKS
7. ADVANTAGE & DISADVANTAGE
3. INTRODUCTION
● MRI is a technique in a radiology which uses
magnetism, radio waves and computer to produce images
of body structure.
● Human body is mainly composed of fat and water which
makes the human body composed of about 63% hydrogen.
● WHY ARE PROTONS IMPORTANT TO MRI?
● Positively charged.
● Spin about a central axis.
● A moving charge creates a magnetic field.
● The straight arrow indicates the direction of the
magnetic field.
4. HISTORY
● In 1971 at Stony Brook University, Paul Lauterbur applied magnetic
field gradients in all three dimensions and a back-projection
technique to create NMR images.
● He published the first images of two tubes of water in 1973 in the
journal Nature, followed by the picture of a living animal, a clam,
and in 1974 by the image of the thoracic cavity of a mouse.
● Lauterbur called his imaging method zeugmatography, a term which was
later replaced by (N)MR imaging.
● In the late 1970s, physicists Peter Mansfield and Paul Lauterbur,
developed MRI-related techniques, like the echo-planar imaging (EPI)
technique.
5. USES
❖ Anomalies of the brain and spinal cord
❖ Tumros, cysts and other anomalies in various parts of
body
❖ Breast cancer screening for women who face a high risk of
breast cancer
❖ Injuries or abnormalities of the joints such as the back
and knee
❖ Certain type of heart problem
❖ Diseases of liver
❖ Fibroids and endometriosis
❖ Suspected uterine abnormalities in women undergoing
evaluation for infertility.
6. COMPONENTS
● A magnet which produces a very powerful uniform magnetic
field.
● Gradient magnets which are much lower in strength.
● RF coils to transmit radio frequency.
● A very powerful computer system which translates the signals
transmitted by th coils.
● Gradient magnets have much lower magnetic field and are used
to create a variable field.
7. PRINCIPLE
➢ Spinning atoms (hydrogen) face outside magnetic
field.
➢ Energy absorption by RF coils.
➢ Resonance of hydrogen atoms measured by RF antenna
which the received signal is sinusoidal in shape.
➢ Imaging by the computer which receives mathematical
data which is converted through the use of a
fourier transform into an image.
8. HOW DOES IT WORKS?
I.Put the subject in big magnetic field.
II.Transmit radio waves into subjects.
III.Receive radio waves that has been re
transmitted by the subject.
IV.Store the data and repeat step 2.
V.Process raw data to reconstruct images.
VI.Getting high resolution images.
9. ● When placed in a large magnetic field, hydrogen atoms
have a strong tendency to align in the direction of
magnetic field.
● Inside the bore of the scanner the magnetic field runs
down the centre of the tube in which the patient is
placed, so the hydrogen protons will line up in either
the direction of feet or the head.
● The majority will cancel each other but the net no. of
protons is sufficient to produce an image.
10. ADVANTAGES
● Provide very detailed diagnostic pictures of most
of the important organs and tissues in your body.
● Ability to diagnose, visualize, and evaluate
various illness.
● Are generally painless.
● Did not use radiation and are therefore suitable
for use in children and pregnant women.
11. DISADVANTAGES
● Limited availability.
● It is lengthy procedure eg. a pituitary gland MRI
scan can take up to 30 min.
● MRI scanning cannot be performed in the presence
of foreign bodies or metallic implants eg.
pacemakers.
● It is relatively expensive compared with other
forms of imaging.
