0:01

When we use dementia imaging with PET, again, we mention there is amyloid

0:05

PET, tau PET, and FDG, and obviously they have different appearances.

0:09

The top row is normal, the bottom row is abnormal. An abnormal PET

0:13

will show diffuse binding of the tracer throughout the cortex. Tau PET is

0:18

not a diffuse, it's really you get tau deposition often in the temporal

0:22

lobes, but it tends to deposit where you have areas of atrophy.

0:28

In this patient here in the temporal lobes, and then this is an

0:31

FDG PET, and there'll be a different pattern for the different types of

0:34

dementia syndromes. This patient happens to have Alzheimer's and they have

0:37

cortical hypometabolism here in the bilateral parietal lobes at a different

0:41

level. You would also see in a temporal lobes, also in the posterior cingulate

0:44

gyrus here. Now, with FDG PET, here's a look at FDG PET with

0:50

different types of dementias with Alzheimer's. Again, we see the cortical

0:53

hypometabolism in the bilateral parietal lobes with FDG,

0:58

we were going to see it with frontotemporal dementia in the bilateral frontal

1:01

lobes, as well as the temporal, and dementia with Lewy bodies can often

1:06

have almost like an Alzheimer's type pattern, but plus occipital lobe.

1:10

So here we see some hypometabolism in the parietal lobes. There's a little

1:14

bit actually in the frontal lobes here. We would have probably seen some

1:17

in the temporal and the occipital as well. And this is an amyloid

1:21

case in a patient with Alzheimer's disease. Here's the amyloid PET CT fusion

1:26

images. Here's the amyloid PET MR fusion. Again, diffuse binding of that

1:31

amyloid tracer throughout the cortex tells us that this patient has Alzheimer's

1:36

disease in most cases. Now, depending on the different imaging modalities,

1:42

there's going to be a different pattern that you look for.

1:45

So with MRI for Alzheimer's, you're going to look for atrophy in the

1:49

temporal, parietal, and posterior cingulate gyri. Frontotemporal dementia,

1:53

it's going to be temporal, frontal, and anterior cingulate gyri. Then with

1:57

dementia with Lewy bodies, it's going to be occipital, and then also you

2:01

can get some temporal, parietal, and posterior cingulate gyrus. Now, the

2:04

pattern of hypometabolism that you see with FDG PET is the same as

2:09

the pattern of atrophy that you see with MRI. So these are basically

2:13

the exact same distribution as with MRI. Skipping down here to tau PET,

2:18

again, for Alzheimer's disease and tau PET, it's going to match the same

2:22

pattern that you see with MRI and FDG. So temporal, parietal, and posterior

2:26

cingulate gyri, is where you'll get that tau deposition. The one that is

2:30

different is the amyloid PET because again, that is a diffuse pattern and

2:34

we use that for screening for Alzheimer's disease.