MRI vs. CT: What’s The Difference

We often get the question, “What’s the difference between a CT scan and an MRI scan?” As diagnostic imaging professionals, we can sometimes forget that to the average individual, this can be a pretty confusing topic. At face value, MRI’s and CT’s seem similar in a lot of ways, but these procedures also have some pretty big differences that patients should be aware of as well.

Basic function:  CT scans are most commonly used to view bone injuries, problems in the lungs or chest, and for detecting cancer. MRI’s, on the other hand, are better suited for examining soft tissue injuries, particularly in the ligaments or tendons. They’re also good for spinal cord injuries and brain tumors.

Cost:  CT’s are generally less expensive than MRI’s. A CT scan can cost anywhere between $1,200 and $3,200, whereas MRI’s can range anywhere from $1,200 to $4,000.

Radiation Exposure:  One of the biggest benefits of an MRI is the fact that the scan is radiation-free. Because the images are produced from a magnet rather than x-ray, patients aren’t at risk of being exposed to any radiation. CT’s, on the other hand, expose patients to low but still significant amounts of radiation. The average radiation dose of a CT scan can range from 2-10 mSv, which is approximately as much general radiation exposure as someone receives in 3-5 years. Repetitive exposure to higher levels of radiation could potentially lead to cancer, so patients are cautioned against excessive or unnecessary CT scans.

Comfort level/scan time:  MRI’s get a bad rep sometimes for overall patient experience. The scan time is much longer, ranging anywhere from 15 minutes up to two hours, and it’s extremely important for patients not to move while being scanned. Due to the amount of time that patients have to spend with restricted movement inside the machine, anxiety or claustrophobia is common among MRI patients during the procedure. Although using an open MRI machine instead of a closed one can help soothe patient claustrophobia, there’s nothing that can be done about the amount of time the patient must remain in the machine. This is where CT scans have the upper hand. Most CT scans are complete within 5 minutes, and the actual scan time can be less than 30 seconds, so patients don’t have to worry about claustrophobia. Shorter scan times also makes for less patient discomfort, and slight movement during the scan isn’t as big of a deal when working with CT’s. CT’s are more commonly used in emergency rooms, specifically because they’re a much faster procedure. 

Limitations:  Although CT scans are undoubtedly more comfortable for patients than MRI’s are, there are some limitations to both procedures. Although CT’s are great for injuries related to bone, they’re not as versatile as MRI’s are overall. They’re also not as easily equipped for getting multiple angles without moving the patient. While MRI’s can produce images in any plane, there are more limitations about what types of patients can have them. Patients with cardiac pacemakers, tattoos, and metal implants are sometimes unable to have the procedure. Patients can get a CT scan regardless of metal implants, but anyone who weighs over 450 pounds may not physically fit inside the scanner or may be over the weight limit for the table. MRI’s provide open options that accommodate heavier patients.

When it comes down to it, neither of these procedures are better or worse than the other, they’re both great for different situations. Both have pros and cons, benefits and limitations, and it’s up to your doctor to determine which one better suits your needs. Either way, we’re happy to be able to provide our patients with both options!

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