Know Before You Go: MRI

Know Before You Go: MRI

The MRI is a painless procedure that can help diagnose a number of conditions.

The magnetic resonance imaging (MRI) machine is a large piece of medical equipment—intimidating for some, since your body slides inside it. You may not be sure how it works or what it does, only that your healthcare provider wants you to get an MRI study. But there’s no reason to worry. Getting an MRI is a painless process that takes less than an hour in many cases, according to radiologist Bruce Railey, MD, with Medical City Arlington in Arlington, Texas.

The MRI scan is a sophisticated imaging test healthcare providers use to help diagnose medical conditions. “It’s a cross-sectional imaging technique that uses a combination of magnetic fields and radio frequency fields to generate an image,” says Dr. Railey. One MRI test can produce dozens of images—each is called a slice—of the body part being studied.

Who needs an MRI?
Your healthcare provider may send you for an MRI for a variety of reasons. It’s mostly used to look at soft tissue like muscles and organs, as opposed to bones, according to Railey. “One of the MRI’s original applications was the imaging of the brain and spinal cord, and that is still a very common use,” he says. ”But it has also become very valuable in imaging of tendons, ligaments, joint cartilage and other soft tissue. It’s become instrumental in the imaging of the liver because it’s very sensitive in detecting if a tumor has spread from the liver to other sites.”

While there’s no evidence that an MRI would harm a pregnant woman or a fetus (although healthcare providers typically try not to order MRIs in the first trimester), tell your healthcare provider if you’re pregnant, or if you have a medical device like a pacemaker or an infusion pump inside your body.

Before you go
Insurance companies may require a preliminary test, such as an X-ray, before they will cover an MRI. “That’s not uncommon with insurance companies, but it’s not what a physician would consider a requirement,” says Railey. “An X-ray may show an abnormality of a bone, but the MRI is far more sensitive in detecting anything with the muscles, tendons, ligaments or cartilage.”

You may need to stop eating and drinking four to six hours before the scan, depending on what body part is being scanned. For some procedures, especially tumor imaging, you may need a contrast dye administered intravenously. “The dye can increase the tissue contrast between normal and abnormal areas,” Railey says.

What to expect during the procedure
The procedure takes between a half hour and an hour, depending on how many parts of your body are being scanned. You may need to wear a hospital gown if your clothes have metal on them, like zippers. You’ll also need to remove any metal jewelry. Imaging facilities typically provide lockers for storing valuables.

The MRI machine itself is a large machine with a tunnel in the middle, open on both ends. You’ll lie on your back on a table that slides inside the tunnel. It’s a tight squeeze and may cause claustrophobia in some people.

The technician will position whichever body part is being imaged, and it’s important to stay still throughout the procedure so the images don’t come out blurry. The machine intermittently makes a lot of noise, so you will likely be given earplugs or headphones with music. Some facilities have open MRI machines that are less confining; ask your healthcare provider if one is available.

“Most people are OK, but the noise and claustrophobia are the two most common complaints,” says Railey. There will be a technician in the room running the machine, and you will be able to communicate with the technician via a two-way radio, Railey says. Tell your healthcare provider before the test if you are prone to claustrophobia; taking a mild sedative before the procedure is not uncommon. If you take medication to be sedated, you won’t be able to drive yourself home; bring a family member if you think you’ll need medication.

After the test
Once the study is completed, the machine generates the images. “It then becomes the radiologist’s job to look at the images in conjunction with the patient history and why the study is being performed,” says Railey. The radiologist then makes a written report, which is sent to your primary healthcare provider. Your provider will discuss the results with you, along with any next steps that may be required.

Medically reviewed in January 2019.

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