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| Ever wonder what a MRI does? Do you wonder how it works? Here is some basic information on the most powerful diagnostic imaging system, the MRI. |
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What is MRI?
How does MRI work?
What are the advantages of MRI?
Are there any risks?
More Information
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| What is MRI? |
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Magnetic resonance imaging (MRI) is an imaging technique used primarily in medical settings to produce high quality images of the inside of the human body. MRI is based on the principles of nuclear magnetic resonance (NMR), a spectroscopic technique used by scientists to obtain microscopic chemical and physical information about molecules. The technique was called magnetic resonance imaging rather than nuclear magnetic resonance imaging (NMRI) because of the negative connotations associated with the word nuclear in the late 1970's. MRI started out as a tomographic imaging technique, that is it produced an image of the NMR signal in a thin slice through the human body. MRI has advanced beyond a tomographic imaging technique to a volume imaging technique.
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| How does MRI work? |
If you have ever seen an MRI machine, you know that the basic design used in most is a giant cube. The cube in a typical system might be 7 feet tall by 7 feet wide by 10 feet long (2 m by 2 m by 3 m), although new models are rapidly shrinking. There is a horizontal opening through the middle of the doughnut running through the magnet from front to back. This interior section is known as the bore of the magnet. The patient, lying on his or her back, slides into the bore on a special table. Whether or not the patient goes in head first or feet first, as well as how far in the magnet they will go, is determined by the type of exam to be performed. MRI scanners vary in size and shape, but the basic underlying engineering is the same. Once the body part to be scanned is in the exact center or isocenter of the magnetic field, the scan can begin.
In conjunction with radio wave pulses of energy, the MRI scanner can pick out a very small point inside the patient's body and ask it, essentially, "What type of tissue are you?" The point might be a cube that is half a millimeter on each side. The MRI system goes through the patient's body point by point, building up a 2-D or 3-D map of tissue types. It then integrates all of this information together to create 2-D images or 3-D models.
MRI provides an unparalleled view inside the human body. The level of detail we can see is extraordinary compared with any other imaging method. MRI is the method of choice for the diagnosis of many types of injuries and conditions because of the incredible ability to tailor the exam to the particular medical question being asked. By changing exam parameters, the MRI system can cause tissues in the body to take on different appearances. This is very helpful to the radiologist (who reads the MRI) in determining if something seen is normal or not. We know that when we do "A," normal tissue will look like "B" -- if it doesn't, there might be an abnormality. MRI systems can also image flowing blood in virtually any part of the body. This allows us to perform studies that show the arterial system in the body, but not the tissue around it. In many cases, the MRI system can do this without a contrast injection, which is required in vascular radiology.
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| Advantages of MRI? |
Why would your doctor order an MRI? Mainly because the only way to see inside your body any better is through invasive procedures ie: surgery. MRI is ideal for:
Diagnosing multiple sclerosis (MS)
Diagnosing tumors of the pituitary gland and brain
Diagnosing infections in the brain, spine or joints
Visualizing torn ligaments in the wrist, knee and ankle
Visualizing shoulder injuries
Diagnosing tendonitis
Evaluating masses in the soft tissues of the body
Evaluating bone tumors, cysts and bulging or herniated discs in the spine
Diagnosing strokes in their earliest stages
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| Are there any risks? |
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If you have a pacemaker or other implant (hip, shoulder, etc.), it is a good idea to tell this to your doctor before going to your MRI. Because of the powerful magnetic fields involved, MRI can cause stress to these objects.
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| For more information, please check the links below: |
How does MRI Work? From howstuffworks.com
The Basics of MRI
RadiologyChannel: MRI
The Visible Human
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