Mri ppt

1. Magnetic resonance iMaging
Prepared by,
Anand & Shonima
Niranjan Ultrasound India pvt.Ltd

2. MRI
• 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.
Niranjan Ultrasound India pvt.Ltd

3. Niranjan Ultrasound India pvt.Ltd

4. HISTORY
1920 1930 1940 1950 1960 1970 1980 1990 2000
1924 - Pauli
suggests that
nuclear particles
may have
angular
momentum
(spin).
1937 – Rabi
measures magnetic
moment of nucleus.
Coins “magnetic
resonance”.
1946 – Purcell
shows that matter
absorbs energy at a
resonant frequency.
1946 – Bloch
demonstrates that
nuclear precession can
be measured in detector
coils.
1972 –
Damadian
patents idea for
large NMR
scanner to detect
malignant tissue.
1959 – Singer
measures blood
flow using NMR
(in mice).
1973 – Lauterbur
publishes method
for generating
images using
NMR gradients.
1973 –
Mansfield
independently
publishes
gradient
approach to MR.
1975 – Ernst
develops 2D-
Fourier
transform for
MR.
NMR renamed
MRI
MRI scanners
become clinically
prevalent.
1990 – Ogawa and
colleagues create
functional images
using endogenous,
blood-oxygenation
contrast.
1985 – Insurance
reimbursements
for MRI exams
begin.
Niranjan Ultrasound India pvt.Ltd

5. FATHER OF MRI
• Magnetic resonance imaging inventor
Niranjan Ultrasound India pvt.Ltd

6. NOBAL PRIZES FOR MRI
•1944: Rabi
Physics (Measured magnetic moment of nucleus)
•1952: Felix Bloch and Edward Mills Purcell
Physics (Basic science of NMR phenomenon)
•1991: Richard Ernst
Chemistry (High-resolution pulsed FT-NMR)
•2002: Kurt Wuthrich
Chemistry (3D molecular structure in solution by NMR)
•2003: Paul Lauterbur & Peter Mansfield
Physiology or Medicine (MRI technology)
Niranjan Ultrasound India pvt.Ltd

7. WHAT CAN BE DIAGNOSED BY AN MRI
SCAN?
•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
Niranjan Ultrasound India pvt.Ltd

8. WHO CAN’T HAVE AN MRI SCAN?
•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
Niranjan Ultrasound India pvt.Ltd

9. 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.
Niranjan Ultrasound India pvt.Ltd

10. CONTI..
•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.
Niranjan Ultrasound India pvt.Ltd

11. Randomly arranged
hydrogen atom
After the strong magnetic
field applied
Niranjan Ultrasound India pvt.Ltd

12. Niranjan Ultrasound India pvt.Ltd

13. Niranjan Ultrasound India pvt.Ltd

14. MAIN COMPONENTS OF MRI
•Scanner
•Computers
•Recording hardware
Niranjan Ultrasound India pvt.Ltd

15. SCANNER
•An MRI scanner is a large tube that contains powerful
magnets.
•Main components of scanner
–Static magnetic field coils
–Gradient coils
–RF (radiofrequency) coils
Niranjan Ultrasound India pvt.Ltd

16. Niranjan Ultrasound India pvt.Ltd

17. Static Magnetic Field Coils
•Three methods to generate magnetic field
1.Fixed magnet
2. Resistive magnet
3.Super conducting magnet
•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
•They need the coils to be soaked in liquid helium to reduce
their temperature to a value close to absolute zero.
Niranjan Ultrasound India pvt.Ltd

18. 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 variation in the magnetic field permits localization of
image slices as well as phase encoding and frequency
encoding.
•The set of gradient coils for the z axis are helmholtz pairs,
and for the x and y axis paired saddle coils.
Niranjan Ultrasound India pvt.Ltd

19. Niranjan Ultrasound India pvt.Ltd

20. RADIOFREQUENCY COIL
•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
• Helmholtz pair coils consist of two circular coils parallel
to each other.
• They are used as the z gradient coils in MRI scanners
•Paired saddle coils are also used for the x and y gradient
coils.
Niranjan Ultrasound India pvt.Ltd

21. ADVANTAGES OF MRI
•No ionizing radiation
•Variable thickness in any plane
•Better contrast resolution
•Many details without iv contrast
Niranjan Ultrasound India pvt.Ltd

22. DISADVANTAGES OF MRI
•Very expensive
•Dangerous for patients with metallic devices placed within
the body
•Difficult to be performed on claustrophobic patients
•Movement during scanning may cause blurry images
•RF transmitters can cause severe burns if mishandled
Niranjan Ultrasound India pvt.Ltd

23. SHAPES OF MRI MACHINE
Niranjan Ultrasound India pvt.Ltd

24. CLOSED MRI
Niranjan Ultrasound India pvt.Ltd

25. OPEN MRI
Niranjan Ultrasound India pvt.Ltd

26. UPRIGHT MRI
Niranjan Ultrasound India pvt.Ltd

27. FUNCTIONAL MRI
•Since the early 1990s, FMRI has come
•FMRI is based on the same technology as MRI
•FMRI looks at blood flow
•It is a technique for measuring brain activity
•It works by detecting the changes in blood oxygenation and
flow that occur in response to neural activity
Niranjan Ultrasound India pvt.Ltd

28. DIFFERENCE BETWEEN MRI AND FMRI
MRI
•Views anatomical
structure
•Focuses on protons in
hydrogen nuclei
•High spatial resolution
•Utilized for
experimental purposes
FMRI
•Views metabolic
function
•Calculates oxygen
levels
•Long-distance
resolution
•Utilized for diagnostic
purposes
Niranjan Ultrasound India pvt.Ltd

29. MRI scan
FMRI scan
Niranjan Ultrasound India pvt.Ltd

30. Niranjan Ultrasound India pvt.Ltd

31. MANUFACTURERS OF MRI
Niranjan Ultrasound India pvt.Ltd

32. Niranjan Ultrasound India pvt.Ltd

33. Niranjan Ultrasound India pvt.Ltd

34. Niranjan Ultrasound India pvt.Ltd

35. Niranjan Ultrasound India pvt.Ltd

36. Niranjan Ultrasound India pvt.Ltd

37. MARKET
Niranjan Ultrasound India pvt.Ltd

38. Niranjan Ultrasound India pvt.Ltd

39. Niranjan Ultrasound India pvt.Ltd

40. Niranjan Ultrasound India pvt.Ltd

41. Niranjan Ultrasound India pvt.Ltd

42. VIDEOS
•https://www.youtube.com/watch?v=AwXJNXNcLNs
•https://www.youtube.com/watch?v=HQGhqE2G6zg
•https://www.youtube.com/watch?v=wqrBWK8Vtwo
Niranjan Ultrasound India pvt.Ltd

43. Niranjan Ultrasound India pvt.Ltd