Learn About the Difference between a CT scan and MRI

CT/CAT Scan and MRI Technology Defined

What is the difference between a CT scan and MRI? A CT or CAT scan is a Computed Tomography scan. The technology behind CT/CAT scans combines x-rays with computer technology in medical applications. An MRI is a Magnetic Resonance Imaging test. MRIs use the technology of magnetic fields and radio waves in order to perform various medical tests.

CT/Cat Scan and MRI Similarities

To understand the difference between a CT scan and MRI, it can be helpful to first understand the similarities. In some cases, either test can be used to locate or diagnose a medical problem. Both involve a patient laying on a table that is inserted into a machine and both result in showing ‘slices’ of the patient’s body. Though there are similarities between the two, there are difference that can dictate which is used or why one is preferred over the other for certain diagnostic situations

CT/CAT Scan and MRI Testing Uses

CT/CAT scans are generally performed in order to help locate or diagnose tumors, cancer, infection and blood vessel condition. MRIs are generally performed in order to examine, in a non-invasive 3-D way, tissues, organs and the skeletal system. MRIs may be used to help locate or diagnose tumors, aneurysms, stroke, multiple sclerosis (MS) and spinal cord injuries.

CT/CAT Scan and MRI Contrast Dyes

Both CT Scans and MRIs may be performed without contrast dye. The MRI contrast dye gadolinium is considered to be safer than the CT contrast dyes that may be used. One such CT dye is barium sulfate and another is Gastrografin. It is important to note that barium sulfate is radioactive and x-rays use ionization radiation. No radioactive materials or contrast dyes are involved in MRI testing.

CT/CAT Scans vs MRIs

CT/Cat scans were developed first and can be cheaper and easier to conduct than MRIs. This is why, despite the lack of radiation involved in MRIs, CT/CAT scans are still so widely used in medical diagnosis.


MRI – Definition. Mayo Clinic Staff. Mayo Clinic. https://www.mayoclinic.com/health/mri/MY00227

Computed Tomography (CT or CAT) Scan. University of Virginia Health System – Radiology. https://www.healthsystem.virginia.edu/uvahealth/adult_radiology/ct.cfm

Computed Tomography (CAT or CT) Scan. Johns Hopkins Medicine – Neuroradiology Division. https://neuroradiology.rad.jhmi.edu/cat.html

Diagnostic Tests: Computed Tomography (CT Scan). Oncology Channel. https://www.oncologychannel.com/diagnostictests/CTscan.shtml

Information About Intravenous and Oral Contrast Used in CT. Imaginis Corporation. https://www.imaginis.com/ct-scan/contrast.asp

What is an MRI with contrast (dye)? RemakeHealth. January 11, 2009. https://blog.remakehealth.com/blog_Healthcare_Consumers-0/bid/6788/What-is-an-MRI-with-contrast-dye

This post is part of the series: CT/CAT Scans and MRIs

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  1. The Difference between a CT scan and MRI