Share on Pinterest The difference between an MRI and CT scan CT scans and MRIs are both used to capture images within your body. The biggest difference is that MRIs (magnetic resonance imaging) use radio waves and CT (computed tomography) scans use X-rays. While both are relatively low risk, there are differences that may make each one a better option depending on the circumstances.

What are MRIs? Using radio waves and magnets, MRIs are used to view objects inside your body. They’re frequently used to diagnose issues with your: joints

brain

wrists

ankles

breasts

heart

blood vessels A constant magnetic field and radio frequencies bounce off of the fat and water molecules in your body. Radio waves are transmitted to a receiver in the machine which is translated into an image of the body that can be used to diagnose issues. An MRI is a loud machine. Typically, you’ll be offered earplugs or headphones to make the noise more bearable. You’ll also be asked to lie still while the MRI is taking place.

What are CT scans? A CT scan is a form of X-raying that involves a large X-ray machine. CT scans are sometimes called CAT scans. A CT scan is typically used for: bone fractures

tumors

cancer monitoring

finding internal bleeding During a CT scan, you’ll be asked to lie down on a table. The table then moves through the CT scan to take cross-sectional pictures inside your body.

CT scan vs. MRI CT scans are more widely used than MRIs and are typically less expensive. MRIs, however, are thought to be superior in regards to the detail of the image. The most notable difference is that CT scans use X-rays while MRIs do not. Other differences between MRI and CT scans include their risks and benefits: Risks Both CT scans and MRIs pose some risks when used. The risks are based on the type of imaging as well as how the imaging is performed. CT scan risks include: harm to unborn babies

a very small dose of radiation

a potential reaction to the use of dyes MRI risks include: possible reactions to metals due to magnets

loud noises from the machine causing hearing issues

increase in body temperature during long MRIs

claustrophobia You should consult a doctor prior to an MRI if you have implants including: artificial joints

eye implants

an IUD

a pacemaker Benefits Both MRIs and CT scans can view internal body structures. However, a CT scan is faster and can provide pictures of tissues, organs, and skeletal structure. An MRI is highly adept at capturing images that help doctors determine if there are abnormal tissues within the body. MRIs are more detailed in their images.

Choosing between an MRI and CT scan Most likely, your doctor will give you a recommendation based on your symptoms whether you should get an MRI or CT scan. If you need a more detailed image of your soft tissue, ligaments, or organs, your doctor will commonly suggest an MRI. Such cases include: herniated disks

torn ligaments

soft tissue issues If you need a general image of an area like your internal organs, or due to a fracture or head trauma, a CT scan will commonly be recommended.