A brain scan can show a scar with confidence. The harder question is whether that scar is doing anything at all.
A spot of scarring in a region that governs planning or memory or language is a very different thing than the same spot in a stretch of brain that carries little of the patient's daily function.
So when I find a lesion, I do not stop at pointing to it. I ask what that exact region does, and then I look back at the person. Do their symptoms line up with that location, or not.
Sometimes the answer is that the scar is real but silent, and I will say so. Sometimes a small finding in an important region explains everything the patient has been struggling to describe.
A finding without function is just a dot on an image. A finding tied to what the person is living is an answer.
Location tells you where. Function tells you whether it matters.