Refer this ppt which briefly describes about MRI

1. MAGNETIC RESONANCE
IMAGING (MRI)
- SOWMYA SREE
- NMBT
- 10

2. INTRODUCTION
• MRI is a radiology technique
• That uses magnetism, radio waves and a computer to produce
images of body structures
• In 1997 the first MRI exam was performed on a human being
• It took five hours to produce one image

3. FATHER OF MRI

4. 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
• The nuclei can be rotated using radio waves , and they subsequently
oscillate in the magnetic field while returning to equilibrium

5. • Simultaneously they emit a radio signal
• This is detected using antennas (coils)
• Very detailed images can be made of soft tissues

7. MAIN COMPONENTS OF AN MRI
• Scanner
• Computers
• Recording hardware

8. SCANNER
• An MRI scanner is a large tube that
contains powerful magnets
• Main components of scanner
- Static magnetic field coils
-Gradient coils
- Radio frequency coils

9. STATIC MAGNETIC FIELD COILS
• High resolution imaging system uses superconducting magnets
• The superconducting magnets are large and complex
• They need the coils to be soaked in liquid helium to reduce their
temperature to a value close to absolute zero
• Three methods to generate magnetic field - fixed magnet , resistive
magnet , superconducting magnet

10. GRADIENT COILS
• 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
• The set of gradient coils for Z axis are Helmholtz pairs , and for x
and y axis paired saddle coils

12. RADIOFREQUENC
Y COILS
• RF coil 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
• Helmholtz pair coils consist of two circular coils
parallel to each other
• Paired saddle coils are also used for the X&Y
gradient coils

13. PROCEDURE
During the test
• The MRI machine looks like a long narrow tube that has both
ends open. You lie down on a movable table that slides into the
opening of the tube. A technologist monitors you from another
room. You can talk with the person by microphone.
• If you have a fear of enclosed spaces (claustrophobia), you
might be given a drug to help you feel sleepy and less anxious.
Most people get through the exam without difficulty.
• The MRI machine creates a strong magnetic field around you,
and radio waves are directed at your body. The procedure is
painless. You don't feel the magnetic field or radio waves, and
there are no moving parts around you.
• During the MRI scan, the internal part of the magnet produces
repetitive tapping, thumping and other noises. You might be
given earplugs or have music playing to help block the noise.

14. • In some cases, a contrast material, typically gadolinium, will be
injected through an intravenous (IV) line into a vein in your hand or
arm. The contrast material enhances certain details. Gadolinium
rarely causes allergic reactions.
• An MRI can last anywhere from 15 minutes to more than an hour.
You must hold still because movement can blur the resulting
images.
After the test
If you haven't been sedated, you can resume your
usual activities immediately after the scan.
Results
A doctor specially trained to interpret MRIs
(radiologist) will analyze the images from your
scan and report the findings to your doctor.

15. An MRI scan is different from a computed tomography
(CT) scan, which uses X-rays instead of magnets to
produce images.3
While both tests show images of structures of your body,
an MRI is better at showing contrast and details of soft
tissue like the brain, muscles, tendons, ligaments, nerves,
and spinal cord, while a CT scan is typically better for
imaging bones and blood vessels.
For conditions that require frequent imaging, especially
brain conditions, MRI is the best choice because it doesn't
use X-rays or radiation. For emergency situations, a CT
scan is much quicker, so MRI is typically reserved for
situations in which there's time to get detailed pictures.

17. MRI SCAN IMAGE

18. DIAGNOSIS
• Most ailments of the brain including tumors
• Sport injuries
• Prostate problems
• Certain ENT conditions
• Musculoskeletal problems
• Most spinal conditions / injuries

19. CANT HAVE AN MRI SCAN
• A cardiac pacemaker
• A Cochlear implant
• A metallic foreign object
• Had surgery in last 8 weeks
• Certain clips in the head from brain operation
• Pregnant women

20. PROS & CONS OF AN MRI
• No ionizing radiation
• Better contrast resolution
• Variable thickness in any plane
CONS
• Expensive
• Claustrophobic patients
• RF transmitters can cause severe burns if mishandled

22. THANK YOU