Why no mention about the delay in diagnosis because GP's too often refer most early symptoms for a low sensitivity brain scan?

Are you referring to brain MRI scans with and without contrast? MRI without contrast can show a lot, as I understand it, and may be less risky as some people can have reactions to the injected contrast material. Is there some specific disease or condition that you are concerned about diagnosing? Alzheimer's and other dementias can't necessarily be diagnosed with any specificity based on MRIs, with or without cpontrast. A scan can show if there are areas of shrinking in the brain or evidence of old brain damage. For example, if a person has dementia symptoms and evidence of previous mini-strokes on the MRI scan, a dr. might suspect vascular dementia. MRIs can show if there are tumors or blood vessel malformations or areas of demylenization, as in MS.

I don't understand. It sound interesting but what is low sensitivity vs high? And how do you get one or the other and what shows up or doesn't?

Are you speaking of scans to diagnose illness or aging?

There is a massive difference.

We need more info.