Someone asked me recently what the difference is between a CT scan and an MRI and I couldn't answer them. I am a relatively new grad working in LTC. I haven't had any exposure to these tests except what we went over in school. I've been studying on it and this is what I've come up with. A CT scan is cheaper, faster, and it uses radiation . It will show bones where an MRI will not. An MRI uses magnetism and radio waves.It shows the same thing as a CT scan except it will not show bones. Is there anything else I should know when explaining the difference to someone? If some one is having neurological problems why would a CT scan be ordered before an MRI? The person who asked me the difference thought that the 2 tests showed the same thing but that an MRI was better so they wanted to know why you wouldn't start with an MRI if the test wasn't needed to show bones.