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General Radiology

MRI (Magnetic resonance Imaging)

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MRI uses a magnetic field and radio waves together with a computer to create cross-sectional, three-dimensional pictures of the head and body. Detailed MRI images allow physicians to better evaluate parts of the body for conditions, such as cancer, heart and vascular disease, stroke, musculoskeletal disorders that may not be visible with other imaging methods.
Functional Magnetic Resonance imaging of the Brain (fMRI)
FMRI is a cutting edge procedure that uses MR imaging to measure the tiny metabolic changes that take place in an active part of the brain. This procedure is usually recommended for physicians to examine the anatomy of the brain. A procedure called brain mapping helps determine specific areas of the brain that control critical functions such as thought, speech, movement and sensation. This is critical in the prognosis and assessment of the effects of stroke, trauma or degenerative disease (such as Alzheimer’s) on the brain function. FMRI is also a pivotal tool to set plans for surgical treatment of the brain and radiation therapy and monitor the growth and function of brain tumors.
Preparation

Preparation is the key to both your comfort and results when taking an MRI. Here are some of the elements you should watch out for when taking an MRI.

  • You can either wear a gown provided by the clinic or your own clothing as long as it is loose fitting and has no metal fasteners. Think sweatpants and a loose t-shirt.
  • Guidelines about eating and drinking vary with the specific exam; patients may follow regular diet and medications as usual unless specified by the doctor.
  • If the MRI requires an injection of contrast material into the bloodstream, the radiologist or technologist will ask for details of allergies of any kind, such as allergy to iodine or x-ray contrast material, drugs, food, the environment, or asthma. The contrast material most commonly used for an MRI exam is called gadolinium. Because gadolinium does not contain iodine, it can be used safely in patients with contrast allergies.
  • Be sure to outline medical history to your radiologist; they will need to know of any serious health problems or recent surgeries. Some conditions, such as severe kidney disease may prevent taking contrast material for an MRI.
  • You should always inform your physician or technologist if there is any possibility of pregnancy.
  • If you have claustrophobia (fear of enclosed spaces) or anxiety, physicians can prescribe a mild sedative prior to the scheduled examination.
  • Jewelry and other accessories should be left at home if possible, or removed prior to the MRI scan. Because they can interfere with the magnetic field of the MRI unit, metal and electronic objects are not allowed in the exam room. These items include:
    • Jewelry, watches, credit cards and hearing aids
    • Pins, hairpins, metal zippers and similar metallic items
    • Removable dental work
    • Pens, pocket knives and eyeglasses
    • Body piercings
  • In most cases, an MRI exam is safe for patients with metal implants, except for the following:
    • Internal (implanted) defibrillator or pacemaker
    • Cochlear (ear) implant
    • Some types of clips used on brain aneurysms
    • Some types of metal coils placed within blood vessels
  • You should inform the technologist of electronic devices in your body, because they may interfere with the exam or potentially pose a risk. Some implanted devices require a short period of time after placement (usually six weeks) before being safe for MRI examinations. Examples include but are not limited to:
    • artificial heart valves
    • implanted drug infusion ports
    • implanted electronic device, including a cardiac pacemaker
    • artificial limbs or metallic joint prostheses
    • implanted nerve stimulators
    • metal pins, screws, plates, stents or surgical staples
  • In general, metal objects used in orthopedic surgery pose no risk during MRI. However, a recently placed artificial joint may require the use of another imaging procedure.
  • Patients who might have metal objects in certain parts of their bodies may also require an x-ray prior to an MRI. You should notify the technologist or radiologist of any shrapnel, bullets, or other pieces of metal which may be present in your body due to accidents. Foreign bodies near the eyes are particularly important.
  • Dyes used in tattoos may contain iron and could heat up during MRI, but this is rarely a problem.
  • Tooth fillings and braces usually are not affected by the magnetic field, but they may distort images of the facial area or brain, so the radiologist should be aware of them.

 

Procedure
Any procedure performed has a process and knowing exactly how this is going to take place is the key to your comfort:

  1. You will be positioned on the moveable examination table. Straps and bolsters may be used to help maintain the correct position during imaging.
  2. Devices that contain coils capable of sending and receiving radio waves may be placed around or adjacent to the area of the body being studied.
  3. A device is positioned around the area to be examined.
  4. If a contrast material will be used in the MRI exam, a nurse or technologist will insert an intravenous (IV) catheter, also known as an IV line, into a vein in your hand or arm. A saline solution may be used. The solution will drip through the IV to prevent blockage of the IV catheter until the contrast material is injected.
  5. You will be moved into the magnet of the MRI unit and the radiologist and technologist will leave the room while the MRI examination is performed.
  6. When the examination is completed, you may be asked to wait until the technologist or radiologist checks the images in case additional images are needed.
  7. The intravenous line will be removed.
  8. MRI exams generally include multiple runs (sequences), some of which may last several minutes.
  9. The entire examination is usually completed within 45 minutes.