0:00

Well, this is a 45-year-old physician who

0:03

had a CT for another reason and had a lesion

0:08

or a mass incidentally discovered in the

0:10

patient's right kidney, the viewer's left.

0:13

So the four images I have up are an in-phase

0:16

GRE, so-called IPGRE, an out-of-phase or OOPGRE.

0:23

I've got an axial T2, spin echo, water

0:26

weighted image without fat suppression

0:28

on the lower left and on the lower right.

0:31

I've got a very early arterial phase.

0:33

The contrast hasn't reached the kidney yet.

0:35

So this is a T1 GRE, a T1 appearing

0:38

GRE without contrast yet in the kidney.

0:40

So essentially, a non-contrast image of this

0:43

lesion that is superficially located posteriorly.

0:46

So the whole point here is to discuss a

0:49

hypo-intense lesion arising from the kidney.

0:55

So here we are, T2 dark lesions again.

0:57

So our diagnostic differential with T2

1:00

dark lesions are going to be a papillary

1:03

RCC, a hemorrhagic cyst, or lipid-poor AML.

1:07

So going through that exercise, we go right

1:10

to the T1 to see what it looks like on T1.

1:13

And as we talked about in the prior vignette, we look

1:16

at the brightness on T1, and can we describe it as

1:20

being a bloody cyst, being 2 to 2.5 times background?

1:24

If it is, we can clearly be confident that

1:27

it's a hemorrhagic cyst and put it to rest.

1:29

Unfortunately, in this case, it's

1:31

not 2 to 2.5 times background.

1:33

So, we have to take hemorrhagic

1:35

cysts out of our differential.

1:36

And the two that we are worrying with now

1:38

are, are we dealing with a lipid-poor AML?

1:41

Or are we dealing with a typical hemorrhagic cyst?

1:45

You know, that just, um, you

1:47

know, doesn't meet all the criteria or

1:49

are we dealing with a papillary RCC?

1:52

So we can go to our in-phase out-of-phase to see

1:54

if we can find either bulk fat or intravoxel fat.

1:58

So what do you think?

1:59

Well, let's put up the appropriate images.

2:01

Here's the in-phase and here's

2:03

the out-of-phase of this lesion.

2:05

I don't really see much dropout in it at all.

2:07

Right, so I see no dropout to confirm intravoxel

2:10

fat, and I don't see an India ink interposed

2:13

between the fluid and the lesion to suggest bulk fat.

2:18

So what

2:19

you mean is there's no interface right

2:20

here between the, the, uh, water in

2:24

the renal parenchyma and the lesion.

2:26

That's correct.

2:26

So this India ink sign should go right

2:29

on through this lesion if it was a

2:30

fat-containing lesion, and it doesn't.

2:32

Or, said another way, or shown another

2:34

way, you should see it right here, and you don't.

2:36

So, no India ink sign, no dropout, no

2:39

microscopic fat, no macroscopic fat.

2:42

And as far as the signal, if you're using the

2:45

background, the background is the renal parenchyma.

2:47

It's almost iso-intense, equal to the renal parenchyma.

2:50

So it doesn't in any way fit the

2:52

profile of a hemorrhagic cyst.

2:54

And, in fact, it also doesn't

2:55

fit the profile of an AML either.

2:58

That's right.

2:58

So we're still stuck with,

3:00

uh, is this a lipid-poor AML?

3:03

Is this a papillary RCC?

3:06

Or is this just a hemorrhagic cyst

3:08

that doesn't meet classic criteria?

3:10

So the next things we would look

3:12

at would be, how does it enhance?

3:14

So let's look at if there's any enhancement,

3:17

and then I would look at diffusion in the sense

3:20

of, um, looking to see if there's restriction.

3:23

If there's restriction, that would also

3:25

err us towards a neoplasm and not a cyst.

3:28

Sure.

3:28

So let's, let's move on in our vignette and talk about,

3:31

uh, the vascular supply of this lesion or lack thereof.

3:35

And, uh, you know, if this is a papillary cancer, they

3:37

are more common in men who are in the right age range.

3:40

So that's still

3:42

in the differential diagnosis.

3:44

Let's move on, shall we?

3:46

Dr. Pina, Dr. Pomeranz, P and P out.