MRI Exam FAQ - Frequently Asked Questions

What is MRI and how does it work?

• Magnetic resonance imaging, or MRI, is a way of obtaining very detailed images of organs and tissues throughout the body without the need for x-rays.
• Instead, MRI uses a powerful magnetic field and radio waves , to construct images of the body.
• A rapidly changing magnetic field and a computer are used to create images that show whether or not there is an injury or some disease process present.
• For this procedure, the patient is placed within the MR scanner—typically a large, tunnel or doughnut-shaped magnet that is open at both ends.
• The magnetic field aligns atomic particles called protons that are present in most of the body's tissues.
• Radio waves then cause these particles to produce signals that are picked up by a receiver within the MR scanner.
• The signals are specially characterized using a changing magnetic field, and computer-processor to create very sharp images of tissues as "slices" that can be viewed in any orientation.
• An MRI exam causes no pain, and the magnetic fields produce no known tissue damage of any kind.
• The MR scanner may make loud tapping or knocking noises at times during the exam; using earplugs prevents problems that may occur with this noise.
• You will be able to communicate with the MRI technologist or radiologist at any time using an intercom system or by other means.

How safe is MRI?

• The powerful magnetic field of the MR system will attract iron-containing (also known as ferromagnetic) objects and may cause them to move suddenly and with great force.
• This can pose a possible risk to the patient or anyone in an object's "flight path."
• Great care is taken to be certain that objects such as "ferromagnetic" screwdrivers and oxygen tanks are not brought into the MR system area.
• It is vital that you remove all metallic belongings in advance of an MRI exam, including watches, jewelry, and items of clothing that have metallic threads or fasteners.
• The powerful magnetic field of the MR system will pull on any iron-containing object in the body, such as certain medication pumps or aneurysm clips.
• Every MRI facility has a screening procedure and protocol that, when carefully followed, ensures that the MRI technologist and radiologist knows about the presence of metallic implants and materials so that special precautions can be taken. In some unusual cases the exam may have to be canceled.
  
  Contra-Indications to an MRI
  
  
• Cardiac pacemaker
• “Ferromagnetic“ aneurysm clip
• Hearing aid
• Inner ear cochlea implants
• Metal fragments in eye
• Spinal cord and neurostimulators

• If you have a bullet or other metallic fragment in your body there is a potential risk that it could change position, possibly causing injury.
• In addition, a metallic implant or other object may distort the MR images or make it difficult for the MRI system to "tune" to your body.
• This may be unavoidable, but if the radiologist knows about it, allowances can be made when interpreting the images.
• For some MRI studies a contrast material called "gadolinium" may be injected into a vein to help improve the information seen on the MR images.
• Unlike contrast agents used in x-ray studies, a gadolinium-based contrast agent does not contain iodine and, therefore, rarely causes an allergic reaction or other problem.

The question of claustrophobia

• Some patients who have MRI may feel confined, closed-in, or frightened.
• Perhaps one in twenty will require a sedative to remain calm.
• Today, many patients avoid this problem when examined in one of the newer MRI units that have a more "open" design.
• We often permit a relative or friend to be present in the MR system room, which also has a calming effect.
• If patients are properly prepared and know what to expect, it is almost always possible to complete the examination.
• If patients require sedation , you are not allowed to drive after the procedure and require a friend or family member to accompany you, so that they can drive you after the examination.

Pregnancy and MRI

• If you are pregnant or suspect you are pregnant, you should inform the MRI technologist and/or radiologist during the screening procedure.
• In general, there is no known risk of using MRI in pregnant patients .The safety of MRI in pregnant patients has not been documented.
• Its use is therefore reserved to address very important problems or suspected abnormalities.A limited scan is therefore performed.
• Gadolinium, the contrast agent used in MRI has not been proven safe in pregnancy and is therefore not administered.
  
  Breast Feeding & MRI
  
  
• You should inform your radiologist if you are breast-feeding at the time of a scheduled MRI study.
• If you need to receive gadolinium, the MRI contrast agent,you should not breast feed for 24 hours after the injection, to allow the contrast agent to be cleared from your circulation.
• This is because, gadolinium can be transmitted via breast milk.
• One option under this circumstance is to pump breast milk before the study, to be used until injected contrast material has cleared from the body, which typically takes about 24 hours.

NB: Patients Must Bring Old X-Rays and scans for all procedures!