0:00

At Johns Hopkins,

0:03

we tend to look at the diffusion-weighted imaging

0:06

and the ADC values in a qualitative fashion.

0:10

There have been publications that have looked at

0:12

ADC values with regard to distinguishing between

0:16

benign and malignant neoplasms of these salivary

0:19

glands, and the number that has been suggested,

0:22

at least in some of the publications,

0:24

is that this value of greater than 1.8 times ten

0:27

to the three millimeter squared cut-off for

0:31

distinguishing pleomorphic adenomas

0:33

versus malignancy.

0:35

The neoplasm that sort of confounds us, however,

0:39

is the Warthin's tumor.

0:41

This is a tumor that often is darker

0:44

in signal intensity on T2-weighted scans

0:45

and may be hypercellular,

0:47

and therefore its values may overlap that

0:50

of the malignant values. However,

0:53

when you have something that's pretty bright on

0:55

the DWI and shows high numbers on the ADC values,

1:00

it really suggests that it's

1:02

a pleomorphic adenoma.

1:08

We do not routinely do perfusion imaging for

1:13

parotid or other salivary gland neoplasms.

1:17

Nonetheless,

1:19

there have been some publications

1:20

which you can see here,

1:22

that have suggested that with the dynamic contrast-enhanced technique you can see

1:27

a slow progressive perfusion,

1:29

which kind of makes sense on the post-gad scans

1:35

where we see the pleomorphic adenoma imbibe more

1:38

and more contrast on delayed imaging, as opposed to

1:43

Warthin's tumor, which has a faster

1:45

uptake and a faster washout

1:47

when you look at the perfusion maps.

1:49

And a malignancy,

1:51

which is fast uptake but a flatter,

1:53

slower washout.

1:54

So if you have ADC values that are overlapping

1:57

between Warthin's tumors and malignancy,

1:59

some people have said try perfusion-weighted imaging. To be honest,

2:02

the aspiration of parotid masses is pretty simple

2:04

to do and doesn't require large

2:08

needles, and therefore,

2:11

going with cytology or a true-cut needle biopsy

2:18

of a parotid mass will solve this.

2:22

And here are some of the values that

2:24

are given for blood volume,

2:26

blood flow, and mean transit time

2:27

for various tumors,

2:30

including pleomorphic adenomas and

2:32

Warthin's tumors versus malignancies.

2:39

If you have pleomorphic adenomas,

2:42

it makes sense that you would have monomorphic

2:46

adenomas. In general, these lesions,

2:49

which are benign tumors,

2:51

have similar imaging characteristics

2:54

to pleomorphic adenomas,

2:56

with the exception that they often are slightly

2:59

less bright on the T2-weighted scan.

3:01

So you have myoepitheliomas,

3:04

canalicular adenomas, and basal cell adenomas

3:08

as examples of monomorphic adenomas.

3:13

So I believe I have one case I'd like

3:15

to show you of monomorphic adenoma.