0:00

60-year-old with elevated PSA of 6

0:03

and a firm prostate on exam.

0:05

So we have the axial T2, the ADC map windowed at 1400.

0:11

1400, the interpolated B equals 1600 axial series, and

0:16

the arterial phase of the dynamic post-contrast series.

0:19

So I always start by looking in the peripheral zone.

0:22

In this case, the peripheral zone has

0:25

kind of a heterogeneous appearance.

0:27

It's got some areas of decreased T2

0:29

signal, but nothing well-defined.

0:31

And you kind of put that in your report because

0:33

you're saying, "Hey, we're maybe decreasing

0:35

the sensitivity a little bit because the

0:37

peripheral zone isn't beautiful, right?"

0:39

And if we look on the ADC map, we notice that the

0:41

peripheral zone is pretty uniformly bright throughout.

0:46

And there are some areas where it's a little bit dark.

0:49

But when I window the ADC map at 1400,

0:51

1400, I'm looking for black holes.

0:54

On the ADC map to alert me, uh, to an

0:57

area of diffusion restriction, and I

0:58

want to see it look very, very focal.

1:01

And I use a cutoff ADC of a thousand, raise my

1:04

red flags that this might be something that's

1:07

going to be a PI-RADS 4 or a PI-RADS 5 lesion.

1:10

The literature kind of supports using a

1:12

value of 900, but I go up to a thousand.

1:15

That way if it's a thousand and ten, I know

1:17

I'm still above my cutoff, and I don't have

1:19

to sort of move those goalposts all the time.

1:22

So no diffusion restriction

1:23

sitting in the peripheral zone.

1:25

No errors of low T2 signal

1:26

and nothing focally enhancing.

1:28

There's a lot of diffuse

1:29

enhancement, but nothing focal.

1:30

So no lesions or suspicious

1:32

errors in the peripheral zone.

1:34

Now I move to the transition zone, and again

1:36

it has this typical, organized chaos

1:40

appearance of BPH as you go superiorly protrudes

1:44

into the bladder base, and this is kind of normal.

1:47

There's no areas of T2 signal abnormality

1:49

that worry me in the transition zone.

1:53

Next, we look at the central zone.

1:56

The central zone is going to correspond like

1:58

this region here, into here and here, and we

2:01

go down to here, and if I open up the coronal

2:04

images, we see the transition zone is here.

2:09

So you notice here is that the

2:10

transition zone is asymmetric.

2:12

It's increased in size on the left, and

2:15

it's larger than it is on the right.

2:17

And if we look in the region of the

2:19

ADC map, there is some focal diffusion

2:22

restriction that's a little asymmetric.

2:24

The ADC value measures at around

2:28

850, if I remember correctly.

2:34

Rectangle will be fine, right?

2:37

So a mean of about 810, which is quite low, and

2:40

it's equivocally bright on the high B value images.

2:47

The high B value images can be difficult

2:49

because they're relative signal intensities,

2:52

and you can window things to be really

2:54

bright and window things to be really dark.

3:00

lesions based on diffusion in the peripheral zone,

3:04

which for these purposes includes the central zone.

3:07

Something has to be diffusion

3:10

restricting on the ADC map, i.e.

3:12

3:12

a black hole with these windows or ADC value less

3:16

than a thousand and bright on the high B value images.

3:21

And if it only meets one of those

3:22

criteria, it gets a PI-RADS 3.

3:26

And then if it enhances it can

3:27

be bumped up to a PI-RADS 4.

3:29

So in this case, because the finding was

3:32

asymmetric and the ADC value was 800, which is

3:36

well below my threshold of a thousand, I called

3:39

it a PI-RADS 4 lesion, even though you could

3:41

strongly argue it to be a PI-RADS 3 lesion.

3:45

Now this person's PSA density was above 0.

3:48

15, which means that a PI-RADS 4 or 3 would get

3:51

a biopsy the way we were practicing at the time.

3:55

So this was called a PI-RADS 4 lesion based

3:58

on the diffusion restriction, kind of ignoring

4:00

the rules, and no contrast enhancement.

4:04

And then when this was biopsied, we got

4:08

benign tissue and some inflammation and the

4:11

systematic, uh, biopsies did not show anything.

4:14

Uh, oops, we forgot, sorry, we jumped a little bit.

4:17

We've got the anterior stroma.

4:19

Here's a little bit of normal

4:20

anterior stromal thickening.

4:21

It's smooth.

4:22

It kind of goes into the cleft between the

4:24

two lobes of the transition zone, but it's

4:27

not really insinuating between nodules.

4:30

It's not showing any enhancement.

4:33

Not showing any enhancement,

4:34

it's pitch black, and that's normal tissue.

4:37

Um, so, kind of the moral of this case is that,

4:41

uh, when I see asymmetric, um, central zone,

4:46

that, that's really diffusion restricting, I'll

4:49

call that a lesion, with the caveat that it

4:51

could represent asymmetric, um, central zone.

4:55

Central zone normally can be low signal

4:57

on T2 and diffusion restricting, so

5:00

if it's symmetric, call it normal.