I don't know anything about this sort of thing, but if your neurologist has seen the MRI showing this and does not seem to be worried that you are a 'walking time bomb' then I would guess that you are not.

I complain about neurologists and their knowledge of PCS a lot but I would have thought that interpreting abnormal MRI scans is something they would be better at, something they really would have been trained well to do. Sounds scary but I think it would be best for you to try not to worry too much, if you can.