0:00

Dr. Finazzo, we're back with our 45-year-old physician, uh,

0:01

3 00:00:04,210 --> 00:00:06,710 who we studied and evaluated on the prior vignette.

0:06

He had this low signal T2 lesion,

0:10

or hypointense lesion, uh, seen on an MRI that was

0:13

incidentally discovered on a CT for another reason.

0:17

And I've got before you,

0:18

essentially, the non-contrast MRI.

0:21

I've got a little bit of arterial phase contamination.

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There's our lesion.

0:24

And then we have phase 1, phase 2, phase 3, a

0:28

subtraction in the lower left-hand corner, and in the

0:31

lower right-hand corner in the blue trunks, we've got a

0:34

delayed, uh, T1 MRI, where we've actually measured the

0:38

signal intensity, and we'll talk about how to do that.

0:41

And

0:45

that's exactly what our goal is at this point is, is

0:48

there an enhancement, is this a solid lesion or not?

0:51

Um, and so basically when we look at our

0:56

arterial and portal venous phase imaging,

0:59

uh, papillary RCCs tend to hyperextend,

1:03

bow enhance, or demonstrate

1:05

slow progressive enhancement.

1:07

So what we want to do is we want to look at the

1:09

maximum enhancement on the post-contrast and compare

1:13

it to the pre-contrast examination as one option.

1:17

If we can't visually see it or can't measurably see

1:22

it, then we try to use our subtraction images to look

1:27

for enhancement, making sure that we realize and look

1:31

for any misregistration, uh, too much signal noise.

1:35

Um, and then if that doesn't help, we then

1:37

go to our diffusion to look to see if there's

1:40

any restricted lesion that we can also suggest

1:43

that it's a solid, uh, highly cellular lesion.

1:46

So we might have a little bit of

1:48

misregistration right here, and you would

1:49

look at the edge of the liver to, to see that.

1:52

And I think you alluded to this, um, Mr.

1:54

Signal intensity index, uh, SII we'll call it.

1:59

And that's gonna consist of the signal intensity post.

2:04

So post-SI minus pre-SI over pre-SI.

2:12

And I think you had mentioned that a rise of 15 percent

2:15

or greater would suggest the presence of a neoplasm.

2:19

As opposed to either some type of low-grade

2:21

or reactive or inflammatory enhancement.

2:23

That's correct.

2:24

And we use percentages and although physicists

2:27

don't like us to use that because there's really

2:29

no noise map that maps the pre and the post.

2:33

Uh, we've all accepted a 15 percent change

2:37

as being acceptable to document enhancement.

2:41

But again, beware.

2:42

That we can get misregistration on our subtraction

2:47

images so as not to over-call, uh, pseudo enhancement.

2:52

And secondly, be very careful when the area

2:56

you're trying to draw your region of interest.

2:58

Interest in the area that most maximally enhances

3:02

and we can get artifact if the, if the region of

3:05

interest that we're trying to measure is too small.

3:08

So in, in summary, we want to make sure that

3:11

the area of enhancement is not too small

3:14

and that we're not getting misregistration

3:16

in the subtraction-weighted images.

3:18

And you pointed this out to me earlier in papillary

3:20

tumors, which men get, and they are, you know,

3:24

strongly in the differential diagnosis here.

3:26

They're multiple about, uh, you know, 23

3:29

percent of the time, bilateral 4 percent

3:32

of the time, this is a single one.

3:34

You said, when you're, when you're looking

3:35

at subtractions, yes, you should subtract

3:38

early on, but when you have a lesion that does

3:40

basically this, it enhances kind of very slowly.

3:44

If you subtract too early down here,

3:46

you're not going to see anything.

3:47

So you want to subtract. If you're going to do

3:49

an early subtraction, you should certainly do a

3:51

late subtraction, which I haven't provided you

3:54

with here, to make sure there is no enhancement.

3:56

Thank you.

3:56

Now, one other thing, one other exercise you

3:58

and I did is we went over to this delayed

4:00

one here, and we did an ROI, which you drew.

4:03

We got just a little bit under 1,000 for

4:05

the signal intensity here, and we got close

4:08

to 1,000 here, and close to 1,000 here.

4:10

So, the signal intensity matched almost

4:13

exactly in an earlier arterial phase,

4:16

in the pre and in the delayed post.

4:17

So, we were both comfortable that it was not enhancing.

4:20

That it was not enhancing.

4:21

And that's fact number one.

4:22

And then number two, in the diffusion-restricted

4:26

images, we don't see any restricted diffusion.

4:29

So, that also helps us feel comfortable that we're

4:32

probably dealing with a benign proteinaceous cyst.

4:36

Uh, and on a second point, papillary neoplasms

4:39

are, uh, you know, not as aggressive as a cystic

4:44

renal cell, so we can feel comfortable to watch

4:47

these lesions and, you know, 3 centimeters is

4:50

the criteria that everybody feels comfortable, 2.

4:52

5, 3 centimeters, until we

4:54

want to do something about it.

4:56

So, I feel comfortable in every

4:58

aspect to watch this lesion.

4:59

Yeah, and if there was diffusion restriction, for

5:01

those of you that are new to MRI or not that familiar

5:03

with, you know, on the diffusion-weighted image.

5:06

You'd see something that was white

5:08

or brighter as the B value goes up.

5:10

And when you do the ADC map, it

5:11

would look nice and dark over here.

5:13

We don't, we don't have that in this case.

5:15

Now, it's said that papillary cancer

5:17

arises from a cell that's very similar

5:20

to the proximal convoluted tubule.

5:22

I don't know how that plays into

5:24

the signal intensity character.

5:26

But in this particular patient,

5:27

we, we, we got a 3-month follow-up.

5:29

It was exactly the same.

5:31

We're gonna do a 6-month follow-up

5:32

from there, then a 9, then a 12.

5:34

As opposed to doing anything more invasive,

5:36

we've chosen a very conservative approach.

5:38

And so far, all is good.

5:40

Alright, the two Ps are out.