Preparing For An MRI?


MRI Preparation and MRI Sound Levels

Are you or a loved one preparing to have an MRI? Do you have questions about MRIs? The Mayo Clinic, based in Rochester, MN, gives helpful information. We respect The Mayo Clinic as an excellent source for medical information and guidelines.

By Mayo Clinic staff

An MRI machine
Magnetic resonance imaging (MRI) is a technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within your body. Most MRI machines are large, tube-shaped magnets. When you lie inside an MRI machine, the magnetic field temporarily aligns all the water molecules in your body. Radio waves cause these aligned particles to produce very faint signals, which are used to create cross-sectional MRI images -- like slices in a loaf of bread.

The MRI machine can combine these slices to produce 3-D images that may be viewed from many different angles.



By Mayo Clinic staff

MRI is a noninvasive way for your doctor to examine your organs, tissues and skeletal system. It produces high-resolution images that help diagnose a variety of problems.


MRI of the brain and spinal cord
MRI is the most sensitive imaging test of the brain and spinal cord. It's often performed to help diagnose:
• Tumors • Developmental abnormalities • Aneurysms • Stroke
• Pituitary gland diseases • Multiple sclerosis • Dementia progression • Spinal cord injuries


Functional MRI of the brain (fMRI) can be used to identify important language and movement control areas in the brain in people who are being considered for brain surgery.


MRI of the heart and blood vessels
An MRI that focuses on the heart or blood vessels can assess:
• The size and thickness of walls in the heart's chambers
• The extent of damage caused by heart attack or heart disease
• The buildup of plaques and blockages in the blood vessels
• Structural problems in the aorta, such as aneurysms or dissections


MRI of other internal organs
An MRI may be used to check for tumors or other abnormalities of the:
• Lungs   • Liver   • Kidneys   • Spleen   • Pancreas
• Uterus   • Ovaries   • Prostate   • Testicles


MRI of bones and joints
MRI may be used to help evaluate:
• Joint disorders, such as arthritis
• Joint abnormalities caused by traumatic or repetitive injuries
• Disk abnormalities in the spine
• Bone infections

MRI photo
MRI of the breasts
MRI may be used in addition to mammography to detect breast cancer, particularly in women who have dense breast tissue or who may be at high risk of the disease.

Video - MRI


An MRI visit - Video



  • For most individuals, there are no known harmful effects from exposure to the magnetic field or radio waves used in making MRI images.


By Mayo Clinic staff

During the test
The MRI machine looks like a tunnel that has both ends open. You lie down on a movable table that slides into the opening of the tunnel. A technologist monitors you from another room. You can talk with him or her by microphone.


The MRI machine creates a strong magnetic field around you, and radio waves are directed at your body. The procedure is painless. You don't feel the magnetic field or radio waves, and there are no moving parts around you.


During the MRI scan, the internal part of the magnet produces repetitive tapping, thumping sounds and other noises. Earplugs or music may be provided to help block the noise. If you are worried about feeling claustrophobic inside the MRI machine, talk to your doctor beforehand. He or she may make arrangements for you to receive a sedative before the scan.


An MRI typically lasts about an hour. You must hold very still because movement can blur the resulting images. In some cases, contrast agents are injected into your veins to enhance the appearance of certain tissues or blood vessels in the images.


During a functional MRI, you may be asked to perform a number of small tasks — such as tapping your thumb against your fingers, rubbing a block of sandpaper or answering simple questions. This helps pinpoint the portions of your brain that control these actions.


After the test

If you haven't been sedated, you may resume your usual activities immediately after the scan. Nursing mothers shouldn't breast-feed for 36 to 48 hours after an MRI if a contrast material was used. Very rarely, the contrast material can cause hives and itching.


A radiologist -- a doctor specially trained to interpret MRIs -- will analyze the images from your scan and report the findings to your doctor. Your doctor will then discuss any important findings and next steps with you.

Information obtained from the Mayo Clinic, at www.mayoclinic.com

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 2/16/2011 Update: How To Prepare For Your MRI

After speaking with licensed MRI technicians, The Daily Decibel has learned some interesting things about MRI machines.

      Loudness, Ear protection, Earplugs
  • An MRI machine is loud. We've observed the procedure inside the MRI room. A friend was given an MRI for his upper neck region. We sat in the MRI room with him, for moral support. The procedure lasted several minutes.
  • Because the MRI machine is loud, MRI patients are often offered protective earplugs by the MRI technician. The earplugs can block out some of the noise emitted by the MRI machine. We suggest using at least an 29dB NRR protection. This means a Noise Reduction Rating (NRR) of 29 decibels, designed to block out 29 decibels of loudness.
          How many decibels is an MRI ?
           How can I be prepared? Will my MRI be safe?
    • No matter what part of your body is being imaged, you should be screened by the MRI technician before you get the MRI. Whether it's your finger, your leg, or your brain, you should be screened by the MRI center.
           Did you say they "screen me"?
    • Yes. They screen you to determine whether it's safe to conduct the MRI procedure.
             What about the Magnet on the MRI? What does it do?
      • As stated by the Mayo Clinic, there are no known harmful magnetic effects for most persons. As stated on the Mayo Clinic website: "For most individuals, there are no known harmful effects from exposure to the magnetic field or radio waves used in making MRI images."
            What is "screening"? Why do they screen me?
        Screening means the MRI technician should ask you a series of questions and/or provide you a written questionnaire. (This is also true for visitors who will be in the room during the MRI imaging.) The technician does this to determine whether it is safe to conduct the MRI procedure. The technician will ask you such questions as:
      •    Have you had any implants or surgeries in the past?
      •    Do you have any metal objects in the part of your body that is going to be imaged?
      •    Have you had a shunt (a tube) implanted in your brain?
      •    If you've had a shunt, was it adjustable (with different pressure settings)?
      •    Do you have Hydrocephalus?
             What kinds of questions do they ask in a screening?
      • For examples of screening, see here and here.

             If I already have a shunt or metal implant, will the magnet do any damage?
      • For most individuals, there are no known harmful magnetic effects. The MRI technician will ask you about metal objects because they don't want the MRI magnet to affect any part of your body during the procedure. They are doing this to ensure that the MRI procedure will be safe.
             What if I already have an adjustable shunt?
      • Adjustable shunts have different settings, which the surgeon can change if necessary. If you had an adjustable shunt before your MRI, check with (1) your MRI technician and (2) your shunt surgeon before you have your MRI. They will want to know whether they MRI affected your adjustable shunt setting.
             What if the MRI affected the pressure setting of my adjustable shunt?
      • If, after your MRI, your adjustable shunt setting changed, your MRI technician and your surgeon may recommend that your surgeon adjust it to the level it was before you had the MRI taken.
            Where can I find more information on MRIs ?
      • Please see links below. They are the same links used by many imaging and radiology professionals. And now, you can, too!

      How Many Decibels is an MRI? How Loud is an MRI?
       
      We've had many visitors requesting information about MRI acoustic noise.  This page may provide some information you're looking for.

      The following link is from Dr. Frank Shellock:

      Acoustic Noise and MRI Procedures

      The page includes information on       CHARACTERISTICS OF MR SYSTEM-RELATED ACOUSTIC NOISE.

      Thank you, Dr. Shellock.

      Sincerely,

      Chris Bennett
      The Daily Decibel


      MRI Websites

      MRI Safety Site - by Dr. Frank G. Shellock, Ph.D.
      MRIsafety.com

      The Institute For Magnetic Resonance Safety, Education, and Research 
      www.IMRSER.org

      MRI testing services for implants and devices
      www.MagneticResonanceSafetyTesting.com

      --
      child at an MRI machine

      The MRI machine in the photo above, if you look closely at the letters at the top, appears to be a PHILIPS machine. The PHILIPS MRI home page is here.

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