May 4, 2009 -- Question: When are imaging diagnostics, such as an MRI or PET scan, used to determine whether I have Alzheimer's disease -- and how accurate are they?
Answer: The standardized assessment for Alzheimer's disease includes a brain scan, and it's called a structural brain scan that can be either an MRI or a CT scan. This allows the doctor to see whether there's a tumor or a stroke in the brain. It may show brain shrinkage, which is not especially diagnostic.
Sometimes the doctor may order a brain PET scan, which can help differentiate different types of dementia. For example, it may show Alzheimer's disease or frontal temporal dementia. This can be important because Alzheimer's disease has a different kind of treatment than other types of dementia, like frontal temporal dementia.