0:00

Okay,

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so this is a young woman who was being evaluated

0:05

for follow-up of known multiple sclerosis.

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When I look at the scans for multiple sclerosis,

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I generally have up, initially,

0:14

the axial FLAIR scan,

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the axial T2-weighted scan,

0:18

and the axial diffusion-weighted scan.

0:21

And what I do is I generally scroll through

0:24

these in order to identify the demyelinating

0:27

plaques in the axial plane.

0:29

Initially, as I mentioned,

0:31

on T2-weighted scanning,

0:33

demyelinating plaques are better seen in

0:36

the infratentorial area. So, initially,

0:38

we're going to look at the cerebellum and the

0:41

brainstem on the T2-weight scan, focusing.

0:44

And then as we shift to the supratentorial

0:47

space, the FLAIR scan becomes the dominant,

0:50

most accurate way of evaluating because of the

0:53

Virchow-Robust space perivascular space issue,

0:56

as described previously. Initially,

0:59

I will also have the diffusion-weighted scan

1:01

up to look and see whether there is active

1:04

demyelination with cytotoxic edema,

1:07

and also to exclude another entity,

1:11

such as a stroke,

1:12

that could potentially be simulating

1:15

multiple sclerosis. So, here we go.

1:18

We're going to focus initially on the axial T2

1:21

two-weighted scanning. So, pretty early on,

1:25

we are seeing multiple white matter lesions

1:28

that are coursing through the brainstem,

1:30

as well as affecting the middle

1:32

cerebellar peduncle,

1:33

which is the main tract that connects

1:36

the pons to the cerebellum.

1:39

And we are also seeing more peripheral white

1:42

matter lesions in the left side

1:44

of the cerebellum. Again,

1:46

these cerebellar white matter lesions may be

1:50

better seen on this T2-weight scan than

1:54

looking at the FLAIR scan to the left here.

1:57

So these are the demyelinating plaques in the

2:01

brainstem as well as in the cerebellum.

2:04

As we course more superiorly,

2:08

we see that there is diffuse involvement of the

2:11

left side of the brainstem and the midbrain.

2:15

And now, as we enter the supratentorial space,

2:20

my eyes are going to shift a little bit more

2:22

to the FLAIR imaging because, as I said,

2:25

tends to show the demyelinating plaques in a

2:28

better fashion because CSF on T2-weight

2:31

scan is the same signal intensity

2:33

as the demyelinating plaques.

2:35

So let's just look at these relatively quickly.

2:38

Here we have a large area of demyelination

2:42

in the splenium of the corpus callosum.

2:47

We have white matter lesions that are

2:49

subcortical or juxtaportical,

2:54

and we have demyelination,

2:57

which is occurring in a periventricular region.

3:03

When we talk about the McDonald criteria

3:06

for multiple sclerosis,

3:08

we have to look at four different locations.

3:11

Number one, juxtaportical demyelination.

3:15

Number two, periventricular demyelination.

3:19

Number three,

3:20

infratentorial demyelination in the brainstem

3:23

and cerebellum, and finally in the spinal cord.

3:26

If two or more areas are involved,

3:30

then it satisfies the McDonald criteria for

3:33

dissemination in space within

3:35

the central nervous system.

3:37

So if you look at, for example,

3:40

this area of demyelination in the subcortical

3:44

white matter of the left frontal

3:46

lobe seen on the FLAIR image,

3:49

you can see how that might be mistaken

3:52

for CSF space on a T2-weight scan,

3:56

which is why FLAIR is generally relied

3:58

on most in the supratentorial region.

4:01

Now, currently,

4:03

we're on the B0 map on the

4:06

diffusion-weight imaging,

4:07

and I will just scroll around until we get

4:12

to the B1000 images, which is here,

4:15

to look for areas that are bright

4:17

and signal intensity.

4:18

And we would have to correlate that with the ADC

4:22

map in order to determine whether or not there

4:25

actually is restricted diffusion or whether

4:28

this is merely T2 shine through.

4:30

So, remember, on the ADC map,

4:33

T2 shine through is bright

4:35

in signal intensity,

4:37

whereas active cytotoxic edema is going

4:42

to be dark in signal intensity.

4:46

So if I stop on this image,

4:48

what we see on FLAIR image is

4:51

a demyelinating plaque.

4:53

On the DWI,

4:55

we see it as bright in signal intensity.

4:58

However, on the ADC map in the middle,

5:02

we see that there actually is a small area of

5:05

dark signal intensity in the periphery,

5:08

which might suggest that this has cytotoxic

5:11

edema and therefore is more likely

5:14

to be an active plaque. Now,

5:17

we will also look at the gadolinium-enhanced

5:19

sequences to make that distinction.

5:21

But this is what we're looking for on the ADC

5:26

map. Combined with the diffusion-weighted scan,

5:30

all of the other demyelinating plaques

5:32

are just bright in signal intensity.

5:35

Without dark signal down here,

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we're just seeing some artifact in

5:40

the left lateral temporal lobe.

5:43

I'm going to pull down now,

5:45

the T1-weighted scans

5:48

to show

5:50

whether or not the demyelination is

5:54

showing contrast enhancement,

5:56

indicating active blood-brain.

5:59

Barrier breakdown. So as we scroll,

6:02

we see that much of what is seen in the brain

6:05

stem and cerebrum is not showing

6:07

contrast enhancement. However,

6:09

as we get further superior,

6:12

we come across a lesion in the left corona

6:16

radiata which is showing bright signal intensity

6:19

enhancement on the T1-weighted

6:22

scan post-gadolinium.

6:24

And you note that based on all the

6:27

other FLAIR demyelinate plaques,

6:29

there's no way for us to know that this one

6:32

versus this one versus this one is going

6:34

to show contrast enhancement. However,

6:37

when we do the T1 post-GAD,

6:39

we are noting that this plaque seems to be an

6:42

active plaque by virtue of its enhancement.

6:45

You might want to correlate that with the

6:50

coronal scan,

6:51

and it verifies the contrast enhancement in that

6:55

left-sided plaque. So on the coronal FLAIR,

7:00

what we're seeing is this lesion here,

7:02

which corresponded to the more peripheral

7:04

enhancement on the left side.

7:07

On this same coronal image,

7:08

we see that there are going to be,

7:10

as we go further superior,

7:12

additional plaques that are showing

7:13

contrast enhancement.

7:15

So let's scroll up a little bit more superior,

7:17

and we're starting to see some of these plaques

7:21

that did indeed show gadolinium enhancement

7:24

on the T1-weighted scan,

7:26

as well as peripheral and arcs of

7:30

enhancement on the coronal scan.

7:33

I want to just focus on this coronal scan for

7:36

just a moment because it demonstrates

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the different types of enhancement.

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Of demyelinating plaques.

7:43

You can have open arcs of enhancement.

7:50

You can have a peripheral rim,

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complete rim of enhancement.

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And as you can see in this subcortical

8:03

demyelinating plaque,

8:04

you can have solid

8:06

enhancement.

8:08

So multiple sclerosis plaques show a wide

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variety of contrast-enhancing patterns,

8:15

including solid nodular,

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peripheral complete rim, open rim enhancement,

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and linear enhancement,

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which is how I would characterize

8:26

this demyelinating plaque.

8:30

I want to just show the sagittal FLAIR scan.

8:34

So after I've looked in the axial plane,

8:36

which is my comfort zone,

8:38

I also look at the sagittal FLAIR scan.

8:42

The sagittal FLAIR scan shows the

8:44

midline structures optimally.

8:47

Here we have the midline structures,

8:49

including the corpus callosum,

8:50

and we see this large area of demyelination

8:53

in the splenium of the corpus callosum.

8:56

And you also note the brainstem involvement as.

8:59

As well as some areas of cerebellar involvement.

9:02

On the sagittal FLAIR image,

9:05

one of the areas that you want to look at

9:08

closely is what's called the callosal septal

9:11

interface. The colossal septal interface,

9:14

obviously,

9:14

is that interface between the corpus

9:16

callosum and the septum polysinum.

9:19

And it's this area right here.

9:21

We look at this area for focal areas of

9:24

myelination because that is relatively

9:28

specific for multiple sclerosis.

9:32

Actually not identified in this particular case,

9:34

but it's relatively specific for multiple

9:37

sclerosis and allows us for the differential

9:40

diagnosis of demyelinating disorders.

9:44

This patient also had susceptibility

9:48

weighted images performed.

9:52

And you might get a sense here of the central

9:56

vein identified in some of the plex

10:02

with the perivenular demyelination indicative

10:06

of multiple sclerosis. Finally,

10:09

we should look at the cervical

10:12

spine that was also included.

10:14

And the typical MS protocol includes sagittal

10:19

and axial scans through the

10:21

cervical thoracic spine.

10:23

We don't have to do the lumbar spine because

10:25

obviously the spinal cord generally

10:27

ends at around L1.

10:29

So let's look at the

10:31

scans through the

10:34

cervical spine.

10:36

And I will usually put up the T2-weighted

10:39

scan, the T1-weighted scan,

10:41

and the STIR scan.

10:43

And what one sees in scrolling through these is

10:48

an area of bright signal intensity within

10:51

the spinal cord at the C4-5 level.

10:55

This is on the sagittal scan.

10:57

We're going to confirm this on the axial scan.

11:01

You also note another area of peripheral cord,

11:07

high signal intensity at the C2-3 level.

11:11

When we bring down the sagittal post-gadolinium

11:15

enhanced scan and compare it to the

11:18

pre-gadolinium enhanced scan,

11:20

we are able to define whether or not these

11:24

plaques are going to show contrast enhancement.

11:28

Now let's look at the axial scans.

11:35

So when I'm looking at the axial scans,

11:37

I usually will have either the T2-weighted scan

11:40

or the STIR image available in the Sagittal plane.

11:46

As I scroll through the axials,

11:50

as you can see here, the patient was moving.

11:53

Not the best study. However,

11:55

when we get down where that

11:57

large plaque was,

12:01

we can see that it was affecting the

12:03

right side of the spinal cord.

12:05

So here's the demyelinating

12:07

plaque at that C4-5 level.

12:10

Here is the bright signal intensity in the

12:12

spinal cord on the fast-banecho motion degraded

12:16

scan. And here it is on the gradient echo scan.

12:19

Sometimes it's better on the gradient echo,

12:22

sometimes it's better on the fast-banecho.

12:24

But I think you should include both sequences in

12:27

the axial plane just for the cervical spine.

12:30

For the thoracic spine,

12:31

we only do axial T2-weighted scan

12:34

with fast-banecho technique.

12:36

If we pull down the post-gadolinium

12:38

enhanced scan,

12:42

we are actually able to see quite nicely,

12:46

better on the axial scan than

12:48

on the sagittal scan,

12:52

that this is indeed a

12:55

demyelinating plaque that's showing

12:57

contrast enhancement.

12:59

So it's in the periphery of the spinal cord,

13:01

not centrally,

13:02

but in the periphery of the spinal cord.

13:04

You see that area of active demyelination

13:08

demonstrated by gadolinium enhancement.

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I want to finish this case,

13:13

which is actually a quite illustrative case

13:16

with one other pearl from Dave Usom.

13:19

And that is usually the only thing that is

13:23

performed in the coronal plane is

13:26

post-gadolinium enhanced scan.

13:28

You can reconstruct the sagittal FLAIR

13:31

scans into coronal planes,

13:33

but the one that is performed only in the

13:36

coronal plane is usually post-gadolinium

13:39

enhanced coronal images.

13:42

This is a sequence that I look for demyelination

13:46

or enhancement in the optic nerves.

13:49

Optic neuritis is one of the manifestations

13:53

of multiple sclerosis,

13:55

usually because the sections are

13:57

too thick in the axial plane,

13:59

we usually don't see the optic nerves

14:02

that well on axial scans.

14:05

In the multiple sclerosis protocol, however,

14:09

you get a chance to see enhancement in the optic

14:12

nerves to suggest active optic neuritis on

14:16

your coronal post-gadolinium enhanced scan.

14:18

This is done for the brain.

14:19

So we're looking at all the plaques here

14:21

and we're looking at the plaques.

14:22

But take the time to slow down at the level of

14:26

the optic chiasm and then

14:28

follow the optic nerves

14:31

into the orbits to see whether they are showing

14:36

contrast enhancement. And in this case,

14:39

this is the optic nerve on the right side,

14:41

which is showing mild enhancement

14:45

in its under surface.

14:47

On the coronal image in the pre

14:50

chiasmal right optic nerve,

14:52

you see it's actually somewhat enlarged here.

14:54

So. So let me just highlight that with my pen.

14:58

So this is the.

15:00

Optic chiasm on the left side.

15:02

Here on the right side,

15:03

we're at the junction between

15:05

the prechiasmal optic nerve

15:10

and the optic chiasm,

15:12

and you're seeing that it's enlarged.

15:14

And on its periphery,

15:17

we are actually seeing a little

15:18

bit of contrast enhancement.

15:20

So this patient also appears to have active

15:24

Demyel donation in the optic nerve,

15:26

suggestive of right-sided optic neuritis.

15:30

So, lengthy description,

15:32

but a great illustrative example of the

15:34

different manifestations of multiple sclerosis.