1. Magnetic Resonance
Imaging (MRI) Scans
Chris Ma, Philip

2. Background – How it was developed
Development of the MRI was based on the discovery of
nuclear magnetic resonance (NMR)
Professor Isidor I. Rabi discovered that when nuclei is
exposed to a stronger magnetic force, their presence is
shown through absorbing or emitting radio waves
In 1974, 2 years after he filed in his idea of using MRI for
medical diagnosis, a patent was granted to him for using
MRI in medical diagnosis.
First Full Body MRI Scan was used in 1977 by
Dr. Damadian

3. Picture of the First MRI Scanner

4. Structure of the MRI Scanner
Magnet:
The biggest and most important part in
an MRI scanner
Magnet consists of many coils of wire
through which electricity passes,
resulting in a huge magnetic field
Size and Structure:
Tubular shaped
Around 60cm in diameter
If the diameter is too wide, the magnetic
force might not be strong enough
Set of Coils:
Set of coils that are used for
transmitting radio frequency waves for
different parts of the body

5. How it works?
The hydrogen atoms of the patient lines up along the
magnetic field
Normally, the hydrogen atoms are randomly spinning on their
axis
About half of the hydrogen atoms line up towards the feet
and half towards the head
Although most protons cancel each other out (half to
head; half to feet) there are some that are left called
unmatched protons

6. How it works?
Using the coils, radiofrequency waves are applied to a
certain part of the patient’s body
These radiofrequency waves make the unmatched
protons spin at a particular frequency and direction
The three gradient magnets within the main magnet
allows us to take an accurate picture of any specific area
Finally, the radiofrequency waves are turned off, signaling
data to be sent to the computer

7. Diagram showing the process of an MRI scan

8. Strengths
Excel at showing soft tissue
X-ray is only good for showing bones
Ability to create image in any plane (any area of the body)
Computer tomography is limited to one plane
Images created are more accurate than a lot of other
technologies

9. Weaknesses
Expensive
Systems are expensive to purchase making MRI exams very
expensive
Patient has to hold still for a long period of time
An exam is can vary from 20 to 40 minutes long; some take
even longer! Movement from the patient can distort the exam
Safety concerns
All metallic objects must be removed from the area otherwise
even small metallic objects like paperclips can become
dangerous projectiles
Metallic objects within the patient might malfunction
(pacemaker)

10. References
a short history of the magnetic resonance imaging (mri). (n.d.). Retrieved from http://www.teslasociety.com/mri.htm
Bellis, M. (n.d.). Magnetic resonance imaging mri . Retrieved from http://inventors.about.com/od/mstartinventions/a/MRI.htm
(2008). The Components of an MRI system [Web Photo]. Retrieved from http://static.ddmcdn.com/gif/mri-illustration.jpg
Todd, G., & Edmonds, M. (n.d.). Mri magnets: The major player. Retrieved from http://science.howstuffworks.com/mri1.htm
Todd, G., & Edmonds, M. (n.d.). The other parts of an mri machine. Retrieved from
http://science.howstuffworks.com/mri2.htm
Todd, G., & Edmonds, M. (n.d.). Hydrogen atoms and magnetic moments. Retrieved from
http://science.howstuffworks.com/mri3.htm
Todd, G., & Edmonds, M. (n.d.). What else is going on in an mri scan? Retrieved from
http://science.howstuffworks.com/mri4.htm
Todd, G., & Edmonds, M. (n.d.). MRI images and how they're made. Retrieved from
http://science.howstuffworks.com/mri5.htm
Todd, G., & Edmonds, M. (n.d.). MRI safety concerns. Retrieved from http://science.howstuffworks.com/mri6.htm
(2008). How mri works [Web Photo]. Retrieved from http://static.ddmcdn.com/gif/mri-steps.jpg