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I'd like to talk to you about this next case,

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which is often in the differential diagnosis

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of patients who have a glial tumor.

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This was a patient who had behavioral

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changes and aphasia and agitation.

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The FLAIR imaging shows a mass which has

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low signal intensity on the FLAIR scan

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compared to the surrounding edema.

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And on the ADC map which was also performed,

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one can see the relatively low values of the ADC.

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If we do a region of interest for

0:49

those ADC values of the mass,

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you can see that the numbers on average are about 756,

0:59

but the low range is down at 588.

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This mass showed avid contrast enhancement,

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as you can see,

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and the lesion was crossing the midline and there

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was abnormal signal extending

1:13

into the corpus callosum.

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On the perfusion imaging,

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which was done without color coding,

1:22

you can see that as compared to the gray

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matter which has this darker area,

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the tumor is hypoperfused compared

1:31

to the gray matter,

1:32

but slightly greater perfusion than

1:35

that of the white matter.

1:37

When you have a mass that has low ADC values and

1:42

is not showing very avid perfusion and shows

1:48

homogeneous contrast enhancement and darker signal

1:53

on FLAIR or T2-weighted scanning.

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Let me see whether I have a T2-weighted.

1:58

This is more classic T2-weighted scanning.

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You can see how dark the lesion is.

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You would include in your differential diagnosis

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a lymphoma, as opposed to the glial tumors

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such as glioblastoma.

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So, we usually think of tumors that cross the

2:16

corpus callosum are going to be confined to high

2:20

grade astrocytomas and glioblastomas

2:23

and lymphomas. In this case,

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it has many of the important features of lymphoma

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with the dark on T2, low on ADC,

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kind of intermediate in perfusion

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cerebral blood volume

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and avid contrast enhancement.

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Now, for making this diagnosis,

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if the lesion does go to the dural surface

2:46

or the subarachnoid space, or if you see,

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as in this area over here,

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a small area of ependymal enhancement,

2:56

you might recommend CSF sampling

2:59

as a way to make the diagnosis without having to

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go through a biopsy or craniotomy.

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The importance here is that glioblastomas

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generally are treated with attempts

3:12

at complete resection,

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whereas lymphoma is usually treated with

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chemotherapy and radiation therapy

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and is quite effective.