Sunday, September 27, 2009


Basically taking pictures of the brain. You can't see AD on a regular x-ray. You can see the bones of the skull pretty well, but AD does not affect bones.
Then we have CT Scans Computed Tomography hence CT. or CAT scan. A state of the art imaging technique since the late seventies. CT scanners are quite common now, but were rather a rarity on the late seventies. You can see the brain fairly well, and you can do these with or without contrast dye. These are quite good for diagnosing bleeding in the brain for example.
Then there is MRI, or magnetic resonance imaging. This became state of the art by the late 80's. You can see the brain really well with these.
You can take CT scans or MRI's just about anywhere in the body. MRI's are generally more expensive than a CT but you typically get a more detailed picture with an MRI over a CT. This of course depends on what you are trying to look at.
A CT or MRI does not diagnose AD however, you do see more atrophy or shrinkage of the actual brain as the disease progresses.
This shrinkage is not specific for Ad but it is very very consistent with AD. As the disease moves to advanced stages you see more and more atrophy.
The CT or MRI is one diagnostic tool to help aid in making the diagnosis of AD. But as noted in the previous blog, the diagnosis can never be 100% accurate at this point without looking at the brain tissue.
Other more sophisticated scans are the PET scan positron emission tomography and the SPECT scan, single photon emission tomography.
The PET and the SPECT are generally not mainstays, in the clinical world, as they are very expensive, however they are quite prevalent in the research world. These are the pretty scans that are in color. Unless you are affiliated with a big university or research center, you primary care or neurologist is probably not going to order one of these. These scans are actually better at not just looking at the structure of something like the brain but actually measuring what is happening, in different areas, for example which areas have more metabolism going on and activity, relative to other areas.


karen said...

This is way over my head. But I know mom has lots of brain srinkage According to her doc. after an MRI

Joseph J. Sivak MD said...

Basically there is shrinkage in the total brain mass as the disease progreses. You can see that shrinkage on an MRI or CT Scan. These are the two most common scans or pictures of the brain used in helping diagnose AD. The shrinkage is also called atrophy.

Talking about the book with the Lake Superior wind....... a calm day