A CT scan is a computed tomographic scan: basically a bunch of Xrays taken by cameras and detectors arranged in a circle. Bone, muscle, fat etc. absorb Xrays to varying degrees, so you get an X ray based on all these different densities (calculated by a computer.) MRI is magnetic resonance imaging. It involves using large magnets to get the electrons of certain atoms in your body to align in certain ways, then when the magnet is turned off, the electrons go back to their usual alignment at different times according to what tissue it is. MRI does not use radiation. It is more useful in looking at details of soft tissue (can see things in brain sometimes when CT looks negative.) CT on the other hand is very good for bone and blood and is still very good for soft tissue. Both imaging modalities can be manipulated to give 3-D pictures if needed. The only reason you might need an MRI is that if poor balance is a big poblem for you, balance problems can be linked to lesions in what's called the posterior fossa and that is best examined by MRI. Not sure if this helps. Hope so!