0:00

So, Dr. Finazzo, now that we've established we've

0:01

3 00:00:02,740 --> 00:00:05,779 got a hypervascular arterial phase enhancing

0:05

renal cell carcinoma, which is not a good

0:08

prognostic sign, a poor prognostic sign.

0:11

Some of the other poor prognostic signs include large

0:15

size, tumor necrosis, which may affect the character

0:19

of the diffusion, which I know you're going to discuss

0:21

in a moment, um, obstruction of the renal vein or

0:24

invasion of the renal vein with retroperitoneal

0:28

collaterals, and transcapsular invasion.

0:31

So we've got a diffusion image

0:32

in the upper left-hand corner.

0:34

Could you talk a little bit about if you

0:36

would use diffusion, and if you would,

0:38

how you would use it, and when does it restrict?

0:41

So, diffusion weighted imaging is really

0:43

what we're trying to master at this point.

0:47

Uh, diffusion is really good in the

0:49

two extremes, in cysts and in papillary

0:54

cancers, because of the cellularity.

0:56

When we're dealing with renal cell,

0:59

we're dealing with low signal in diffusion

1:01

weighted imaging,

1:03

and we're dealing with low cellularity.

1:05

So those two combined give us a very poor

1:08

ability to use diffusion in our favor when

1:12

we're dealing with clear cell renal cell.

1:14

But when we're dealing with papillary,

1:16

we will see restricted diffusion.

1:19

The time when diffusion helps us is in

1:24

talking about aggressiveness in renal cell cancers.

1:27

So the more aggressive a lesion is, the more necrotic

1:31

it is, then you will see more restricted diffusion

1:34

in a lesion that you're strongly favoring to be

1:37

a renal cell, a clear cell renal cell carcinoma.

1:40

And

1:41

I know this is confusing.

1:42

It's even confusing for me.

1:44

Um, but I know there's been recent reports

1:46

that there is a correlation, there's a

1:47

rough correlation between the ADC map

1:50

and the restriction of velocity.

1:52

So the lower the velocity, the

1:54

higher the grade of the tumor.

1:56

Unfortunately, you can see velocity restriction in an

1:58

oncocytoma, in a chromophobe, and in an AML.

2:02

So it's not specific for renal cell carcinoma, yet.

2:06

The lower the velocity is on the

2:08

ADC map, the nastier the tumor.

2:09

That's correct.

2:10

And then, but what they're looking

2:12

at now is the intravoxel inherent

2:14

motion, so the first part of the curve.

2:17

And what they found is renal

2:19

cells will have the higher spike.

2:21

A chromophobe will have somewhere in the middle and a

2:24

papillary would be at the lower end of the spectrum.

2:27

And that's how we're trying to use

2:29

diffusion weighted for histologic

2:31

subtyping.

2:32

And so, for those of you that are

2:33

diffusion weighted imaging fans.

2:36

You know, there are four major causes

2:39

of diffusion restriction in the brain,

2:41

but I just want to mention two of them.

2:43

One of them is viscosity.

2:45

And, of course, if you have a necrotic

2:48

tumor, it kind of simulates an abscess.

2:51

So a necrotic tumor or an abscess

2:54

could produce diffusion restriction.

2:57

And the other one that Dr.

2:58

Fonazzo mentioned is cellularity or cell packing.

3:02

So, you know, when you have really, really dense cell

3:04

packing, say a lymphoma or a medulloblastoma of the

3:08

brain, you're going to have diffusion restriction.

3:11

So, as Dr.

3:12

Finazzo mentioned earlier, in a renal cell you have

3:15

very loosely packed cells, so you're not going

3:18

to have cellularity-related diffusion restriction,

3:21

but you could have viscosity-related diffusion

3:24

restriction if you have a fair amount of necrosis.

3:26

That's correct.

3:26

Shall we move on?

3:27

Sure.

3:28

Dr. P and Dr. Finazzo out.