Only two forms of brain scans have been proposed for lie detection. The first is a PET scan or a "positron emission tomography" scan. In a pet scan of the brain, radioactive material is injected into the patient. It is most often used to detect blood flow abnormalities of the brain. I am personally familiar with this type of brain scan.
The second brain scan used for lie detection is called a fMRI or functional magnetic resonance imaging. I am also personally familiar with this type of brain scan as well. This would be considered far less invasive than a PET scan. Basically, you lay down on this thing and get moved into a large tube.
Based on personal experience, I would take a PET scan or fMRI over an EEG (that's nasty because you wear this thing on your head with a ton of electrode thingies on it and then, they have the gall to stick a needle into your skin to put gel in the electrode thingies--you end up looking like Pinhead from Hellraiser afterwards--trust me, I KNOW!). Heck, I think even a CAT scan is more irritating than a MRI.
Iow, Warwick, you are talking to a person who has had a very long and tulmultuous medical history with the bodily scars to prove it and has had firsthand experience with many of the tests that you are talking about. In comparison to other tests, these things are nothing. Absolutely nothing. If you want to talk invasive, then talk to me about the spinal tap that I'm overdue for. I am so not looking forward to that...
Stephanie
In every man there is something wherein I may learn of him, and in that I am his pupil.--Ralph Waldo Emerson