Term:
Magnetic Resonance Imaging (MRI)

Description:
An MRI scan is a radiology technique that uses magnetism, radio waves, and a computer to produce images of body structures. The MRI scanner is a tube surrounded by a giant circular magnet (Shiel). The cool thing that this technology brings new is the use of magnetism versus x-ray, which uses radiation. It is for the most part completely harmless. But sometimes you may have those rare cases when someone may either be allergic to the contrast dye used or a case of claustrophobia. Newer adaptations of the MRI of since been developed including an Open MRI, which allows a patient to stand in a designated area instead of being shoved into a tight cylinder. This type of MRI reduces the risk of a patient becoming claustrophobic during the procedure.

Applications:
A MRI is very essential in today’s time. A MRI scan can basically see what the doctors and surgeons cannot see without using some sort of surgical technique. It can produce very detailed images within the patient’s body. For example, it can scan for spinal cord integrity, trauma to the brain, blockages in arteries, etc. Here is a list of the different types of MRI's available to patients:

Types of MRI Exams

  • An MRI of the brain produces very detailed pictures of the brain. It is commonly used to study patients with headaches, seizures, weakness, blurry vision, etc. It also can further evaluate an abnormality seen on a CT scan. During the brain MRI, a special device called a head coil is placed around the patient's head. It does not touch the patient, and the patient can see through large gaps in the coil. This device is what helps to produce the very detailed pictures of the brain.
  • Cardiac MRI
    Cardiac MRI can evaluate the size and thickness of the chambers of the heart, the extent of damage caused by a heart attack or progressive heart disease, and build-up of plaque and blockages in the blood vessels. It is an invaluable tool for detecting and evaluating coronary artery disease and the function of the heart muscles, valves and vessels.

  • This test is most commonly used to look for a herniated disc or narrowing of the spinal canal (spinal stenosis) in patients with neck, arm, back and/or leg pain. It is also the best test to look for a recurrent disc herniation in a patient who has had prior back surgery.

  • MRI can evaluate virtually all of the bones and joints, as well as the soft tissues. Tendon, ligament, muscle, cartilage and bone injuries can be diagnosed using MRI scans. It can also be used to look for infections and masses.

  • MRI of the abdomen is most frequently used to further evaluate an abnormality seen on another test, such as an ultrasound or CT scan. Thus, the exam is usually tailored to look at specific organs or tissues, such as the liver, adrenal glands or pancreas.

  • For women, pelvic MRI is used to evaluate the ovaries and uterus as follow-up to an ultrasound exam which showed an abnormality. It is also used to evaluate endometrial cancer. For men, pelvic MRI is sometimes used to evaluate prostate cancer.

  • An MRA evaluates blood vessels. The blood vessels in the neck (carotid and vertebral arteries) and brain are frequently studied by MRA to look for areas of narrowing or dilatation. In the abdomen, the arteries supplying blood to the kidneys are also frequently examined with this technique.

Web Resources:
http://www.nlm.nih.gov/medlineplus/ency/article/003335.htm
http://www.radiologyinfo.org/en/info.cfm?pg=bodymr
http://www.lifespan.org/rih/services/diagimag/mri/types.htm

Related Terminology:
Medical imaging
Magnetic resonance microscopy
Magnetic resonance elastography
Neuroimaging software
Nephrogenic fibrosing dermopathy
Nobel Prize controversies
Open MRI

Citations/References:
http://www.medicinenet.com/mri_scan/article.htm
http://www.lifespan.org/rih/services/diagimag/mri/types.htm

Graphics:


Open Upright MRI
Open Upright MRI

Traditional MRI
Traditional MRI