Understanding Magnetic Resonance Imaging Tests

One Common Type of Non-Invasive Testing

Woman getting ready for an MRI
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An MRI, also known as magnetic resonance imaging, is a pain-free non-invasive medical test used to produre two dimensional images of the structures of the body. The process uses intense magnetic fields to make images of the inside of the body.

MRIs are used to detect problems within the body or brain without surgery and can identify abnormalities from outside the body.

Who Cannot Have an MRI

Patients who have an implant in their body that contains metal, such as a pacemaker or some types of orthopedic devices, may not be able to have an MRI as the machine uses very powerful magnets to obtain the images needed. This restriction may also apply for other metal objects in the body, such as bullet fragments, metal shards and similar pieces of metal. This is because the machine uses very powerful magnets to produce the images that are used to diagnose illness and the magnets can potentially attract the metal that is in the body.

If there is any question that a patient may have some type of metal in their body that could interfere with MRI testing the patient can have an X-ray, which typically shows metal clearly, or they can have a CT scan which does not use magnets to produce images of the inside of the body. This is typically not an issue because most patients know if they have any type of implant; however, if the patient is unconscious or unable to provide a medical history the risk of performing this type of scan is obviously higher.

Individuals with titanium in their body are typically able to have an MRI.


The MRI test allows the healthcare team to see the internal structures of the body without making an incision. The test is also quick and able to produce images that are very detailed. For example, if the patient is having stroke-like symptoms, an MRI can be performed to look at the blood vessels of the brain—even very small vessels that would be difficult to examine.

The detailed images produced by an MRI can also be helpful in diagnosing an illness that may be affecting bone, muscle or other types of tissues. If your physician suspects that you have an illness or disease process, an MRI may be ordered in an attempt to identify the problem. In some cases, a diagnosis can be made with an MRI and may prevent or indicate the need for surgery.

Aside from the discomfort of being still in one position while the test is completed, the MRI is not painful. The machine can be rather loud when in operation, but earplugs are often available for those who are bothered by noise.

There is no radiation generated by the MRI machine, so the risks of having an MRI are minimal for the patient who does not have metal in their body.

Open Versus Traditional

In a traditional MRI, the patient is placed on a bed that moves inside a tube, where the MRI is done. An open MRI, an option for patients who are bothered by small spaces or are very large, does not require the patients to be placed in the tube, but is done in the "open."

Patients who need an MRI but have issues with small spaces are often given medicine to reduce their anxiety level prior to the procedure.


MRI can be ordered with or without contrast. Contrast medium is a liquid that is given through an IV, and can allow more detailed images to be obtained. For many patients, an MRI without contrast is performed, followed by the injection of contrast material and a second MRI, this one with contrast. In the past, people with shellfish allergies could not have contrast as it contained iodine. New types of contrast mean that a shellfish allergy no longer prevents the use of contrast.

All areas of the body can be scanned using MRI technology, including the heart and brain.

View Article Sources
  • Cardiac MRI Contraindications.  Emory Healthcare.