MRI- Magnetic resonance imaging

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MRI-Magnetic resonance imaging

• By Prashil Patel

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What is MRI

•  Test that uses a magnetic field and pulses of
  radio wave energy to make pictures of organs and
  structures inside the body.
• Body is placed inside a special machine that
  contains a strong magnet.

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Cont

• An MRI is similar to a (CT) scanner in that it
  produces cross-sectional images of the body
• MRI uses a strong magnetic field and radio waves
  to produce very clear and detailed computerized
  images of the inside of the body.

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Early History of MRI

•  Felix Bloch of Stanford University and Edward
  Purcell of Harvard University made the first
  successful nuclear magnetic resonance, NMR,
  experiment to study chemical compounds in 1946
• NMR creates magnetic fields and radio waves cause
  atoms to give off tiny radio signals. 
•  In the early 1980s, the first "human" magnetic
  resonance imaging (MRI) scanners became
  available, producing images of the inside of the
  body.

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Why Is MRI Done

• Used to find problems such as
•  Tumors
• Bleeding
• Injury
• Blood vessel diseases
• Infection
• MRI scan can be done for
• Head
• Chest
• Blood vessels
• Abdomen and pelvis
• Bones and joins
• spine

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Current technology T1 vs T2 MRI

• T1 MRI
• T1 MRI is known as Spin-lattice relaxation time
• It differentiates fat from water - with water
  darker and fat brighter
• T1-weighted MRI is best for looking at brain
  structures
• The strength of the magnets used in T1 are in the
  0.5-tesla to 2.0 -tesla range

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T1 vs T2 conti

• T2 MRI
• T2 MRI is known as spin-spin relaxation time
• Like T1 MRI, T2 also differentiates fat from
  water, but fat shows darker, and water lighter
• T2 is better for looking at non-enhancing brain
  lesions
• The strength of the magnets used in T2 are in the
  0.5-tesla to 2.0 -tesla range

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T1 Image
T2Image
T1 MRI Scan 1.5 Telsa
T2 MRI Scan 1.5 Telsa
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Proton Density weighted MRI

•  Concentration of protons in the tissue in the
  form of water and macromolecules.(Far, Protein,
  etc)
•  Utilizes the difference in proton densities of
  two materials when T1 and T2 characteristics are
  similar.

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T1-Weighted
T2-weighted
Proton Density Weighted
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limitations of the MRI

• Because of the small space given, some patients
  experience claustrophobia have difficulty in
  cooperating during the study.
• Some obese patients cannot be examined
• Patients with pacemakers and certain
  ferromagnetic appliances cannot be studied
• MRI equipment is expensive to purchase, maintain,
  and operate

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Future direction of the MRI

• Very small scanners for imaging specific body
  parts are being developed
• Researchers at the University of Zurich, has
  recently demonstrated a novel way of enticing
  hydrogen atoms to produce images. This will
  produce images of larger portions of the body and
  at the same time free up some space around the
  patient. 
• The usage of the stronger magnets, 7 tesla will
  produce high definition images but has not yet
  been approved due to high magnetic field.

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Citations

• Department of Health and Human Services
• University of Zurich article
• Discovery Fit Health
• Pubmed.gov
• http//www.medhelp.org
• http//srinivasarao.webs.com