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You.

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So in the next seven or ten minutes,

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I'm going to be discussing

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how do we approach adult intraxial tumor and

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especially focusing on tumor mimics.

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You know, non-neoplastic lesions

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which could look like a tumor.

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So if you look at the definition of tumor,

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it's a Latin word for swelling and

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it's not really synonymous with cancer or neoplasm,

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to which we,

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majority of the times,

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confuse with or misuse it for.

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Here is an example of a lesion which could look

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like a tumor and a non-neoplastic lesion.

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A 41-year-old male presenting with altered

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mental status and expressive aphasia.

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In the emergency department you can see there is a lot

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of vasogenic edema and swelling in the left brighter

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lobe which shows some peripheral kind of thick left

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meningeal enhancement and also has a couple of small areas

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of restricted diffusion which kind of conform to this

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smaller necrotic regions within this lesion.

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And if you look at my impression,

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I say the possibility of an infection or inflammatory

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disease process cannot be excluded.

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A granulomatous disease process is also a possibility.

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A tumor, when I say tumor over here,

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what I mean is a neoplasm seems less likely,

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though focal leptomeningeal metastatic disease

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cannot be completely excluded.

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A venous infarct also seems less likely.

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But I'm considering that and that kind of report when

1:35

I look at that there is a lot of hedging going on.

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I'm not really focusing on one particular differential

1:42

diagnosis because of the appearance of this lesion.

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But I am favoring infection as a very high possibility

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considering especially those small areas of restricted

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diffusion in the necrotic portion of the lesion.

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And this is what happens.

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This patient was managed conservatively and within a

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few weeks you can see the patient comes back to the

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emergency department again and now

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with a much larger lesion,

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clearly increased areas of enhancement and larger areas

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of this necrotic cystic part which

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is showing restricted diffusion.

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And when I see a transformation that quickly

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within a few days or a couple of weeks,

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that's much more concerning for an infection.

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And based on this restricted diffusion,

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this one turned out to be a pyogenic abscess.

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Another example over here, a thick irregular necrotic

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mass in the posterior left frontal lobe.

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And if you look at the differential diagnosis,

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it could be anywhere from a stroke,

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a subacute infarct or hemorrhage could look like that.

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An infection and abscess could look like that.

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Neoplasm I am considering very highly glioma based

2:53

on the irregular necrotic appearance of this mass.

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But metastasis and lymphoma is in the

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differential diagnosis now also.

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Considering cumifactor demyelinating lesion

3:02

in the differential diagnosis.

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But if I look at a scan done just five

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days prior to this baseline scan,

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you can see this lesion again evolved very quickly.

3:14

Five days ago,

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all you could see is that swelling and with some

3:18

peripheral minor enhancement along the cortex over here.

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And within five days, this lesion has increased in size,

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is showing a lot of tissue breakdown and necrosis.

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And if I look at the history,

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this is a young patient with infective endocarditis.

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And with that history and with that quick evolution,

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if I look at the diffusion-weighted images,

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it's very clear that this is really a pyogenic abscess.

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The reason being it's showing restricted diffusion in

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that central necrotic cystic part of the lesion.

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Right. So that turned out to be a pyogenic abscess.

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So pyogenic abscesses typically will show restricted

3:55

diffusion in the central necrotic part.

3:58

Two different patients, two different entities.

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Over here in the upper panel,

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you can see peripheral thin,

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relatively regular rim of enhancement showing restricted

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diffusion in the central necrotic portion.

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The one in the lower panel also has thin rim

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of enhancement and central necrosis,

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but without restricted diffusion.

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And the one in the upper panel

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turned out to be an abscess,

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whereas the one in the lower panel

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turned out to be a glioblastoma.

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So it's very important to look at

4:25

diffusion-weighted imaging.

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Another example over here is a patient who

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presented with a peripheral thick,

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irregular rim enhancing lesion showing some

4:35

restricted diffusion in the central portion.

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And within a week,

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you can see the lesion grew very quickly,

4:42

shows much more increased swelling, edema, mass effect,

4:45

and also has restricted diffusion,

4:47

but more at the nodular peripheral

4:50

component of the lesion.

4:52

Another separate lesion is seen in

4:55

the left cerebral hemisphere,

4:56

and this one turned out to be a fungal abscess and

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aspergillosis so abscesses typically pyogenic abscesses

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will show restricted diffusion

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in the central necrotic part,

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whereas fungal abscesses may show restricted diffusion

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along the peripheral nodular component

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of the abscess also.

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But once I see that quick evolution

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and restricted diffusion,

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you have to consider an infection as a tumor mimic in a

5:22

case like that. So solitary necrotic intraxial masses,

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I can divide them into glioma,

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solitary metastasis abscess or Lymphoma,

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and other entities such as granuloma tuberculoma

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and tumefactive demyelinating lesions.

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And the first thing I want to look at on an imaging,

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if the patient especially has fever and

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is showing restricted diffusion,

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that kind of favors the diagnosis of an abscess.

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On the other hand,

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gliomas if there is especially older individuals,

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multifocal or multicentric disease and

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non-enhancing cortical involvement.

5:59

An infiltration going beyond the

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enhancing part of the tumor.

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Whether you diagnose that with Mr perfusion or Mr

6:06

spectroscopy or on Flare imaging is always indicative

6:10

of a high-grade glioma in an adult patient.

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When I'm trying to consider solitary metastatic lesion

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always look for other enhancing lesions,

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disproportionate edema, history of primary malignancy.

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For example,

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if the patient has lung cancer node kind

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of favors solitary metastasis,

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usually metastasis they don't infiltrate

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beyond the enhancing tumor margins.

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And that's another thing if you can use Mr spectroscopy,

6:37

MR perfusion to diagnose that.

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On the other hand lymphoma and other granulomatous

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tuberculomas they are usually seen in immunocompromised

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patients and may show incomplete ring of enhancement.

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Here is an example adult patient presenting

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with progressive left-side weakness.

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And you can see there is a large tumor-like lesion in

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the right basal ganglia with swelling and mass effect.

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But if you look at the post-contrast images, there is

7:05

incomplete rim of enhancement. And once we see that,

7:09

we know that this is not a tumor,

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it's a tumefactive demyelinating lesion.

7:14

As you can see a month later there is almost complete

7:17

resolution of the lesion with conservative management.

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Another example over here in a 35-year-old individual

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presenting with headache and foot drop,

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numbness and tingling in the hand.

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And what we see on imaging is heterogeneously enhancing

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tumefactive lesion in the right parietal deep

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periventricular white matter has some edema swelling,

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some restricted diffusion.

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But if you look at the post-contrast images, the majority

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of the enhancement is almost like an incomplete ring

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of enhancement. And this is two months later.

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You can see the enhancement kind

7:52

of is changing rather quickly.

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The edema actually has increased and this is

7:56

three years later complete resolution.

7:59

This is another example of a tumefactive

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demyelinating lesion. Now,

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one of the things we do to differentiate tumefactive

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demyelinating lesion from a neoplastic lesion

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such as a glioma. Two different patients,

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one in the upper panel showing you a mass in the left

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cerebral hemisphere whereas the one in the lower panel

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has a mass in the right cerebral hemisphere.

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If you look at the diffusion,

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not much to differentiate between

8:24

the two post-contrast images.

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The one in the lower panel is showing

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you an incomplete rim of enhancement.

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There is some mild marginal enhancement even

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for the patient in the upper panel.

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If I show you the perfusion maps, it's much more clear

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which one is a neoplasm and which one is not perfusion.

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The one in the upper panel is showing you much more

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increased blood volume suggesting that this is a

8:47

neoplastic lesion whereas the one in the lower

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panel is showing you very low blood volume.

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And this is what we typically see with TB to

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demyelinating lesions which could look like

8:57

a high-grade glioma on imaging.

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But if.

8:59

Look at the perfusion,

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they are usually very low on blood volume.

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This is what is already known.

9:06

We published it many years ago looking at

9:08

differentiating tumefactive demyelinating lesions

9:11

from high-grade gliomas based on perfusion.

9:14

Typically,

9:14

high-grade gliomas will show high blood

9:16

volume and also high leakiness,

9:18

whereas tumefactive demyelinating lesions will show low

9:21

blood volume and low leakiness on the perfusion scans.

9:25

And that's one way to differentiate tumefactive

9:27

demyelinating lesions from high-grade gliomas.

9:30

Now,

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sometimes we do fall into a case like this where

9:35

it clearly looks like a high-grade glioma.

9:38

Even on perfusion maps,

9:39

you can see very high blood volume.

9:42

And luckily, we don't see these cases that often.

9:44

This one turned out to be a tuberculoma.

9:47

And I think the only thing we can see in a

9:50

case like that, retrospectively maybe,

9:52

is that thin rim of T2 dark signal which probably

9:56

pointed that this could be something

9:57

other than a glioma. Again,

9:59

I don't expect anybody to make a diagnosis of

10:02

tuberculoma based on the initial baseline

10:05

imaging in a case like this.

10:07

But once in a while we do fall into that where you have

10:10

cases such as tuberculoma presenting like a lesion which

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almost looks like a very high-grade glioma or a GPM.

10:17

This is another example,

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another entity which can look like a tumor.

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Here's a patient sent to one of our neurosurgeons

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for a biopsy to confirm a tumor.

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And when I looked at the scan,

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there's a very well-defined lesion in

10:31

the splenium of the corpus callosum.

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If you look at the T1 weighted images,

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it's actually very bright on T1 weighted images not

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showing much contrast enhancement and showing some

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susceptibility blooming at the periphery of this lesion,

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low in blood volume.

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And this one turned out to be actually a cavernoma,

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right?

10:49

So vascular lesions such as cavernomas

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could mimic a neoplasm on imaging.

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Another entity which we see maybe five to seven cases a

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year in a busy neurosurgical practice which can mimic

11:02

a neoplasm is vasculitis. Here is an example,

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a solid-enhancing,

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heterogeneously enhancing mass in the left frontal lobe

11:11

which was sent for biopsy to confirm the diagnosis

11:14

of a suspected diagnosis of a glioma.

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And when we look at SWI,

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it's showing you areas of susceptibility blooming

11:22

in the central part of the lesion.

11:23

But more importantly,

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DSC-T2* perfusion analysis showed that the lesion

11:29

in fact showed low blood volume even in the regions

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which were not showing susceptibility blooming.

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And this is another way to differentiate a high

11:38

grade glioma from a non-neoplastic entity.

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For example,

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this one turned out to be cerebral amyloid angiopathy

11:47

on histopathology and tissue diagnosis.