Hello, this is Dr. E. Greetings from New York! I'm so glad you posted your question for me to answer, and I aim to provide you with accurate info.
The first thing that it means is that your doctor inappropriately gave you the copy of the radiologist's report, which actually needs to be INTERPRETED by your physician FOR YOU.
Subtle differences in the white matter can actually be as simple as being nothing and even due to the child being so small and hard to control in the scanner (they move around and can distort the image sometimes). The report would read differently if there was a lesion,tumor, edema, swelling, or blood. It does not sound like any of these were present.
Rest assured, mom.