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MRI is a radiology technique
That uses magnetism, radio waves, and a computer to
produce images of body structures.
MRI is based on the principles of NMR
In1997 the first MRI exam was performed on a human
being.
It took 5 hours to produce one image.
MRI
5. WHAT CAN BE DIAGNOSED BY AN MRI
SCAN?
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Most ailments of the brain, including tumours
Sport injuries
Musculoskeletal problems
Most spinal conditions/injuries
Vascular abnormalities
Female pelvic problems
Prostate problems
Some gastrointestinal tract conditions
Certain ear, nose and throat (ENT) conditions
Soft tissue and bone pathology/conditions
6. WHO CAN’T HAVE AN MRI SCAN?
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A cardiac pacemaker
Certain clips in your head from brain operations
A cochlear implant
A metallic foreign body in your eye
Had surgery in the last 8 weeks
If you are pregnant
7. PRINCIPLE
• MRI makes use of the magnetic properties of certain
atomic nuclei.
• Hydrogen nucleus (single proton) present in water
molecules, and therefore in all body tissues.
• The hydrogen nuclei partially aligned by a strong
magnetic field in the scanner.
8. CONTI..
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The nuclei can be rotated using radio waves, and they
subsequently oscillate in the magnetic field while returning
to equilibrium.
Simultaneously they emit a radio signal.
This is detected using antennas (coils)
Very detailed images can be made of soft tissues.
11. SCANNER
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An MRI scanner is a large tube that contains powerful
magnets.
Main components of scanner
– Static magnetic field coils
– Gradient coils
– RF (radiofrequency) coils
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13. Static Magnetic Field Coils
• Three methods to generate magnetic field
1. Fixed magnet
2. Resistive magnet
3. Super conducting magnet
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Fixed magnets and resistive magnets are generally
restricted to field strengths below 0.4t
High-resolution imaging systems use super conducting
magnets.
The super-conducting magnets are large and complex
14. GRADIENT COILS
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Gradient coils are used to produce deliberate variations in
the main magnetic field
There are usually three sets of gradient coils, one for each
direction.
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16. RADIOFREQUENCY COIL
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RF coils act as transmitter and receiver
RF coils are the "antenna" of the MRI system
That transmit the RF signal and receives the return signal.
They are simply a loop of wire either circular or
rectangular
17. ADVANTAGES OF MRI
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MRI is particularly useful for the scanning and detection of
abnormalities in soft tissue structures in the body like the
cartilage tissues
and soft organs like the brain or the heart.
There is no involvement of any kind of radiations in the MRI,
so it is safe for the people who can be vulnerable to the effects
of radiations such as babies.
MRI scan can provide information about the blood circulation
throughout the body and blood vessels and also enabling the
detection of problems related to the blood
circulation.
18. DISADVANTAGES OF MRI
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·MRI scan is done in an enclosed space, so the people
who are claustrophobic, i.e. fearful of being in a closely
enclosed surface, are facing problems with MRI to be
done.
MRI scans involve really loud noises while processing
because they involve a really high amount of electric
current supply.
MRI scanners are usually expensive.
