What's the Difference Between a CT and MRI?

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If you have a imaging appointment coming up, you may be wondering what to expect from the scan. You know you’ll have to hold still and it may take awhile, but what exactly is your doctor looking for?

When it comes to CT scans and MRIs, it's normal to have a lot of questions. Some patients fear these scans because they’re worried about feeling claustrophobic or having an implanted metal device in their body cause harm.

The good news is that most of these scans can be completed relatively quickly, painlessly and at extremely low (if any) risks to the patient.

Put your mind at ease by taking some time to understand their purpose and process. While both types of scans provide highly detailed information about your body to help your doctor get a clearer picture of your health, they have three main differences.

1. The Purpose of CT Scans and MRIs

CT scans (also called CAT scans or computerized tomography) are usually ordered to diagnose serious injuries to the head, lungs, abdomen, spine and pelvis. They can be used to diagnose fractures and to identify the size and location of tumors.

MRIs (also called magnetic resonance imaging) provide a more detailed look. The images from an MRI scan can diagnose problems with the joints, tendons and ligaments, as well as the brain, spine, neck, breast, abdomen and muscles.

2. Scan Times for CT and MRI

Both scans require you to be still, but for different amounts of time. While most of these scans at AdventHealth are completed within 10 to 15 minutes, CT scans take much less time compared to an MRI. The scan time for CT can take as little as five minutes, while MRI scans can take 30 minutes to an hour to complete.

Since MRIs tend to take a little longer, our imaging centers try to make it more comfortable for patients by offering things to help them relax and pass the time, like music, video goggles or soothing wall murals.

We understand MRI and CT scans can be challenging for children. Many little ones find it hard to stay still and can be more anxious about the process. We work to explain the scan and offer strategies to support each child throughout the process, with anesthesia only used when medically necessary.

3. The Risks of CT and MRI

One of the major differences between the two scans is in the nature of the technology. To produce diagnostic images, CTs use X-ray technology and MRIs use radio waves and powerful magnets.

Because CTs use X-rays, they do expose patients to a small amount of radiation. While radiation is always considered a health risk, we ensure that all AdventHealth locations and AdventHealth Imaging Centers use the safest, highest-quality technology possible and follow protocols to minimize and monitor each patients radiation exposure.

We also collect data about our facilities’ overall radiation dosages and exposures, and follow the ALARA (as low as reasonably achievable) principles as well as the Image Gently guidelines for children to ensure the utmost safety.

MRIs carry different risks and restrictions. MRI scan technology uses magnets, which are sensitive to metals. Having metal on or in your body during an MRI can pose a safety risk and cause distortions that can interfere with getting quality images from the scan.

It's important to tell your doctor and imaging technologist if you have any implantable device or object, like a pacemaker, metal pins/screws, aneurysm clips, or even have a job that involves working with metal, because flecks of it can unknowingly get into the eye or under the skin. If unsure, it's always good to check with a radiologist to make sure an MRI is safe for you.

Understand Your Imaging Order

If you're holding a doctor’s order for an MRI or CT scan and feeling anxious, know that your doctor recommends it for a good reason, and there’s an experienced and compassionate imaging team ready to support you.

If you have any concerns or questions about your imaging facility or scan, don't hesitate to contact your AdventHealth Imaging location. We want every patient to be comfortable and have a positive, safe imaging experience.

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