Magnetic Resonance Imaging (MRI)
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What is MRI?
Magnetic resonance imaging (MRI) is a spectroscopic imaging technique used in medical settings to produce images of the inside of the human body.
MRI is based on the principles of nuclear magnetic resonance (NMR), which is a spectroscopic technique used to obtain microscopic chemical and physical data about molecules
In 1977 the first MRI exam was performed on a human being. It took 5 hours to produce one image.
A magnet which produces a very powerful uniform magnetic field.
Gradient Magnets which are much lower in strength.
Equipment to transmit radio frequency (RF).
A very powerful computer system, which translates the signals transmitted by the coils.
The most important component of the MRI scanner is the magnet:
The magnets currently used in scanners today are in the .5-tesla to 2.0-tesla range (5,000 to 20,000-gauss).
Higher values are used for research.
Earth magnetic field: 0.5-gauss
How Does It All Work?
The atoms that compose the human body have a property known as spin (a fundamental property of all atoms in nature like mass or charge).
Spin can be thought of as a small magnetic field and can be given a + or – sign and a mathematical value of multiples of ½.
Components of an atom such as protons, electrons and neutrons all have spin.
THE FUTURE OF MRI
The possibility of having very small machines
that scan specific parts of the body.
The continuing improvements on seeing the
venous and arterial systems.
Brain mapping while the patient does specific
tasks, allowing clinician’s to see what part of the brain is responsible for that task/activity.
Improvements on the ability to do MRI’s of the lungs.
DISADVANTAGES OF MRI
Long scan times
Audible noise (65-115dB)
Isolation of patient (claustrophobia, monitoring of ill patients)
Exclusion of patients with pacemakers and certain implants