Lesions are scar tissue which show up on MRIs. You can get them from infections, prior brain trauma (a car accident or head injury) from allot of different things..
MS lesions are a distinct type of placement and size/ shape in specific areas of the brain. A good Neuro and radiologist can tell if the lesions are MS related or not.
MRI is one of the steps to a MS diagnosis. You also have to have correlating symtoms. If you want more info on the diagnosis of MS, you should read more on the McDonald Criteria. Most of a MS diagosis, is ruling out other things....many, many things present the same way as MS. In order to rule out those things, many tests are done, including blood work, EMGs, sometimes a spinal tap.
Hope this helps...
RRMS- dx 05