Not sure if this is the same thing or not, but may play into it.
I remember talking with an expert in his field (he travelled globally as a reputable trainer for therapists) & him showing me some brain scans of people who had experienced serious trauma (the PTSD kind), when they were asked to recall the traumatic memory. And the interesting thing was that those who did not suffer from PTSD, the areas of their brains that lit up when doing so, were consistant with the area of the brain that is known for storing memory. But when those who did suffer from PTSD recalled their traumatic memory, the areas of their brains consistently lit up much further away from & considerably less than in the area known for storing memory. He also went on to show me, how these scans changed over time & after treatment where, as the PTSD symptoms subsided, the more the brain lit up in the appropriate areas of the brain in a normal/standard way to be expected when recalling the traumatic memory. Thereby concluding (in my very layman's terms) that when we are trying to access our memories through an area of the brain, not fully designed or equipped to do so properly, the result can be suffering from many problematic symptoms, inc. PTSD.
I don't recall it ever being mentioned as a potential diagnostic tool. But rather as a tool to show the importance of the proper processing of traumatic memories, & in some cases moving that traumatic memory from where it is currently being accessed from to where it should be, as an integral part of the healing/recovery process.
I don't know if these are the type of scans they are referring to, but might be helpful info anyway.?