0:00

60-year-old man with an elevated PSA to 5

0:03

without family history or obstructive symptoms.

0:07

For images, we have an axial T2-weighted image.

0:10

We have the axial ADC map, which is windowed

0:12

and leveled at 1400 and 1400, respectively.

0:16

We have an interpolated B equals

0:18

1600 diffusion-weighted image.

0:21

That's our high B value image.

0:23

And we have the arterial phase images

0:25

from a dynamic post-contrast series.

0:27

All right.

0:28

So, The first thing you notice is that

0:29

the transition zone is very large.

0:31

It's compressing the peripheral zone, but

0:33

we look at the peripheral zone anyway.

0:35

On the ADC map, it's very nice, high T2 signal

0:39

throughout, so there are no focal areas of well

0:41

defined diffusion restriction in the peripheral zone.

0:44

And the peripheral zone, Focal diffusion

0:46

restriction is the finding that we use to

0:48

direct us most often to a suspicious lesion

0:51

that's going to be Pirads 4 or Pirads 5.

0:54

The transition zone, uh, is evaluated

0:57

mostly on the T2 images, with diffusion

0:59

and post-contrast having secondary roles.

1:02

The Transition zone is very large.

1:06

It's got a very heterogeneous appearance.

1:07

This is sort of your typical appearance of nodular BPH.

1:11

You have areas of high signal, low signal.

1:13

You have nodules that are very well-defined, right?

1:16

And inside the nodules the

1:18

appearance can be very heterogeneous.

1:20

The finding in the transition zone that

1:22

jumps out at me is this region right here.

1:24

It's about 1.

1:25

5 centimeters in diameter.

1:27

It's well-defined, low T2 signal.

1:34

here and maybe causing some mass effect using the

1:38

Pirads lexicon. Want to know is it circumscribed

1:41

or non-circumscribed and what that means is are the

1:43

margins well-defined or non-well-defined, right?

1:46

Encapsulated is another term in the Pirads lexicon. An

1:49

encapsulated nodule will actually have a well-defined

1:53

low signal rim around it like here and here and here.

1:57

So we're looking at are the margins

1:59

distinct or not distinct. Okay, are we?

2:04

Circumscribed or non-circumscribed.

2:08

So if you look on the axial images, when

2:10

we read this initially, we thought that the

2:12

nodule was non-circumscribed, that its margins

2:15

were not very distinct, and if that's the

2:18

case, this gets called a Pirads 4 lesion.

2:21

Now if you look on the sagittal images, you

2:25

might convince yourself that the margins

2:27

are very distinct, in which case it's not.

2:30

This would be called a Pirads 2.

2:31

So this leads, so this, this leads to some issues.

2:34

And if you can't decide if it's a 2

2:36

or a 4, you can always call it a 3.

2:38

Sometimes you can look at your

2:40

diffusion images to help, um, characterize.

2:43

Because in the transition zone, right, if

2:46

you have a score of 2 based on the T2, but

2:49

you have a score of four for diffusion,

2:52

you can bump the score up to a three.

2:54

And likewise, if you score a three for the T

2:57

two appearance and you have a high diffusion

3:00

score, uh, then you can bump it up to a four.

3:03

Right?

3:04

If the DWI score is five, and since the

3:06

diameter of this is about 1.5 centimeters, if we

3:09

thought it really, truly restricted diffusion,

3:11

it would get a score of five for diffusion,

3:14

and this would become a Pirads 4 lesion.

3:16

Right.

3:16

I know it seems very complicated.

3:22

So in this case, uh, the area has well

3:25

defined diffusion restriction on the ADC

3:29

map, but it doesn't have well-defined focal

3:31

diffusion restriction on the high B-value image.

3:34

So this gets a diffusion score of 3,

3:37

which means we're not bumping up the

3:40

total Pirads score based on the diffusion.

3:42

So that's unfortunate.

3:44

Interpreted this, we had two thought processes.

3:46

One was, um, it may be doesn't have

3:49

distinct margins, and we're going to call it

3:51

a Pirads 4, and we're going to biopsy it.

3:54

The other thought process was, this is the only

3:57

thing in the transition zone that looks like this.

4:01

BPH appearance, but this nodule is solid,

4:04

it's clearly not within an existing nodule,

4:07

it's causing some mass effect on a nodule,

4:10

and it may have diffusion restriction.

4:13

Um, it did not contrast-enhance, all right, which

4:18

didn't factor into our decision very much at all,

4:19

to be honest with you, because um, a lot of things

4:22

enhance or don't enhance in the transition zone.

4:25

This was biopsied and came back as normal tissue.

4:28

Now, this is actually a good case to talk about

4:32

how difficult these studies can be because if

4:35

you look at this patient's PSA density, it's 0.05.

4:39

Alright, so in our practice, uh, we

4:42

only, um, biopsy PI-RADS 3 lesions in

4:45

patients whose PSA density is less than 0.15.

4:51

Uh, and we do that mostly to limit the number of

4:55

biopsies in those patients, so we'll get followed

4:56

up very closely, and the biopsy is pretty invasive.

5:00

Uh, so in this case, if we had decided to call this

5:03

a PI-RADS 3 or 2 instead of a 4, the patient might

5:07

not have gone to biopsy and biopsies aren't the

5:09

most pleasant experience and being a large gland

5:13

and an anterior lesion, this could have been very

5:16

difficult to biopsy and perhaps in retrospect it was.

5:19

So this is probably not the best case to to

5:22

show as the first case in the fellowship, but

5:26

it is a good case to to show how complicated

5:29

sometimes these transition lesions can be.

5:31

In many subsequent cases, we'll see some very

5:33

straightforward peripheral zone lesions, we'll see

5:36

some very straightforward transition zone lesions,

5:38

and we'll see a couple that are difficult like this.

5:40

And the thing to remember is, right, just

5:42

because there are a couple, Um, a small

5:45

number of very, very difficult cases really

5:48

doesn't invalidate the entire technique.

5:50

A lot of sites, including ours, have had

5:52

very great success at limiting the number

5:54

of men requiring an unnecessary biopsy by

5:57

using MRI and using the PI-RADS criteria.

6:00

And we found that when we do this consistently and

6:02

do this well, a very large percentage of the men that

6:05

we biopsy end up having, uh, significant cancer.

6:09

And that really lowers the risk of having a PSA

6:12

test, which is, you may go on to a biopsy you

6:15

don't need, or you may incompletely characterize

6:18

a lesion and end up overtreating low-risk

6:20

lesions and undertreating high-risk lesions.

6:23

So apologies for starting the fellowship

6:25

with a difficult case, uh, but hopefully

6:27

it will be a lot easier from here on out.