What is the difference between an MRI and a CT scan?
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peggylou (
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April 4th, 2007
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I'm not an expert-- my understanding is that a CT scan uses X-rays to generate a 3-model of the internals. The MRI uses really really powerful magnets to vibrate the water molecules to model the insides.
Also CT is cheaper and faster and better for seeing bone and acute bleeding, while MRI has better resolution for soft tissues and organs. An MRI doesn't expose you to X-rays, but you get an MRI if you have metal objects inside you.
both are way to image the body. CT (computed tomography) takes a ton of xrays in a circle around your body to generate "slices" of what's inside. You can get slices, say, 1mm apart of a suspcious tumor. But since they are x-rays, it's radiation and you don't want too much exposure. Good for bones and certain types of cancer.
MRI takes images as well, but uses gigantic magnets to align the molecules in your body. Weird, right? Because of that, it's good at imaging soft tissue, and explains why people with pacemakers (and keys in their pocket) can't have them.
From a cost perspective: one of the reasons MRIs are more expensive is that most use supercooled electromagnets to create the magnetic field; the cost of liquid helium to cool the magnets (and the various associated costs related to simply having liquid helium around) contribute to MRIs being significantly more expensive than x-rays.
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