Difference Between an MRI & Cat Scan

Magnetic resonance images (MRI) and computed tomography (CAT) scans are both advanced tools that offer noninvasive views into the human body. These internal views give doctors the information they need to make informed decisions. They operate in different ways and each have their own advantages.

Function

• Magnetic resonance images (MRIs) and computed tomography (CAT) scans work in different ways. While a CAT scan uses X-rays and produces radiation, MRIs use large magnets and do not create radiation.

Visibility

• MRIs and CAT scans offer different views into the human body. Dense areas, such as tendons and the spine, are more visible with an MRI. However, a CAT scan offers better visibility for soft areas including the lungs and other organs.

Speed

• CAT scans can be performed more quickly than MRIs. Because they rely on computer interpretation and are more complex, a full MRI is generally more time consuming.

Dimensions

• CAT scans create a two-dimensional image, just the same as traditional X-rays. This means that a patient must be physically moved into a different position to change the view. MRIs, however, are three-dimensional. The computer view can be viewed from any perspective, without moving the patient.

Contrast

• Because MRIs are essentially computer models of the body, the contrast of the view can be easily changed at any time. This allows doctors to visualize a particular area with improved clarity. The contrast of CAT scans generally cannot be changed after the scan is finished.