Without having seen your MRI, it sounds like there are "white matter lesions." White matter lesions can be normal in a person, and you get more and more of them as you get older as part of the normal aging process. However, they can also be a sign of something bad going on. Certain disease cause white matter lesions that are very bad, like cancer and multiple sclerosis. What they sometimes do in these cases is repeat the MRI scan, but this time they do it with contrast to see if any of the white matter lesions "light up." Certain disease light up with contrast, like cancer, infections, and active multiple sclerosis lesions. They are repeating this scan WITH CONTRAST to make sure you don't have any lesions that "light up." If they don't light up, then that's good. But the only way to know for sure is to do the scan, so it is important to get the scan.