What you have probably heard is that there is research in Finland that enables neurologist to diagnose Alzheimer's from a 90 minute PET scan along with an injection of a chemical "marker" known as carbon 11-labeled Pittsburgh Compound B, which binds to the beta-amyloid deposits in the brains that are associated with ALZ. It is a new use of the PET technology which was reported in late 2008 with the comment that large scale studies were needed. I don't know if it is used in any standard practice now or how wide spread it could be but it is a promise for the future at least. The interesting thing about this procedure is that it can diagnose the disease before symptoms appear, which is when the current drugs work the best.
I did find it interesting that these test showed amyloid plaques formed by Alzheimers appearing first in the frontal cortex areas, then progressing to the parietal and temporal cortex before ravaging the occipital and sensory-motor cortex. This may explain why memory and judgment are often the brain functions first affected with the onset of the disease. It is the first scientific research to prove what we already know
An MRI scan can show the decrease in brain mass that goes along with Dementia but I don't think they can determine what kind of dementia it is yet. Unless they have a past MRI they can only compare it to a standard and that is not very accurate for diagnosis. You can ask the doctor about the PET scan but he will probably tell you that the technology for doing what you want done is at least a few years in the future. PET scans are lengthy and very expensive, much more so than the more common MIR.
Love, deb
PET Scan question 
Linear Mode
