My NP would tell me "nothing to worry about" whether she knows what's going on or not, but that's beside the point.

GP wasn't asking what they should personally do. They were asking how the doctor would screen for it. (The truth is, the doctor can't/won't-- an annual MRI on every otherwise healthy person, for example, would be prohibitively expensive with how MRIs are currently set up-- and as another commenter pointed out, findings from those can be just as easily ignored or put off until it's too late.)