0:01

We're going to use a 3D set of images,

0:06

acquired, axial, reconstructed,

0:08

sagittal, and coronal to evaluate the

0:12

mapping of the prostate in a PI-RADS 1.

0:16

Now, the 3D Fast Spinecho has the

0:18

advantage of giving you thinner slices.

0:21

This is 1.

0:22

2 millimeters with 50 percent

0:23

overlap with reconstructions.

0:26

You would use that if you're trying to map the

0:29

prostate for ultrasound-guided biopsy or TRUS.

0:34

And you might get a volume by drawing

0:36

around an intraglandular abnormality.

0:40

Say there was a tumor here, you'd

0:42

trace it on every axial projection.

0:45

You'd get a volume and a location of the tumor

0:48

and three-dimensional space for the clinician.

0:51

But there is a price to be

0:53

paid for this technique.

0:55

And the price is contrast, resolution, and

0:58

discrimination between the central region

1:02

and the peripheral zone of the prostate.

1:05

Contrast, resolution, not as good.

1:07

To make matters worse in this case,

1:09

this patient has a slightly lower

1:11

signal intensity uniformly in the PZ.

1:16

Now, let's go back and remember the criteria

1:19

that we use for PI-RADS designation.

1:23

For the TZ, it's all about the T2.

1:28

The T2 is a trump card.

1:30

So, TZ, T2, T2, TZ.

1:32

Easy to remember.

1:33

What's the trump card for the PZ?

1:36

The trump card is the DWI.

1:39

So if there's no diffusion, zero diffusion

1:43

restriction in the PZ, and if there are zero

1:48

nodules or masses in the TZ, you've got a PI-RADS 1.

1:55

It pretty much doesn't matter what happens

1:58

with the other parameters in the TZ

2:00

or in the PZ, as long as these are negative.

2:04

And they are.

2:06

Doesn't matter whether you get enhancement.

2:08

These are negative.

2:09

You're a PI-RADS 1.

2:13

So, let's map out our PI-RADS 1.

2:16

I'm going to start out really high up,

2:17

where I see the vas deferens.

2:21

If you want to learn more about the

2:23

ejaculatory system, go to our anatomic

2:26

And then the seminal vesicles.

2:28

This one's a little grayer,

2:29

that one's a little brighter.

2:30

Okay, as you get older, glands dry

2:32

out, they desiccate, they're gray.

2:34

Do not confuse them with solid tumor infiltration,

2:38

which produces mass effect and crosses boundaries

2:41

and is associated with a prostate mass.

2:43

Patient doesn't have it.

2:45

So now let's go into the upper third of the

2:47

gland, so-called gland base, and we're going

2:53

to discriminate, or try to discriminate

2:56

the peripheral zone from the TZ, which makes up

3:00

most of the central region of the prostate.

3:02

So in order to do that, it's probably

3:06

helpful to go to the sagittal

3:08

and just put a cursor on the PZ.

3:11

So let's do that.

3:12

So this is PZ out here,

3:14

and this is central region.

3:17

Let's get to a level where we can

3:18

really discriminate it better.

3:20

Right there.

3:22

Okay, so I'm gonna take my drawing

3:24

tool, and I'm gonna use my favorite

3:26

color, aquamarine blue, or light blue.

3:30

I'm going to draw the central region

3:32

of the prostate gland and then I'm

3:34

going to color in the peripheral zone.

3:37

And we're going to have a PZA,

3:39

a PZP for posterior, and a PZM.

3:44

And then I'm going to color in the

3:48

transitional zone, which makes up most

3:51

of the central region of the prostate.

3:53

I'm going to color in from the outside in.

3:55

This is all the central area of the prostate.

3:58

And kind of in the middle is the

4:00

urethra and periurethral tissues.

4:02

I'll give that another shade of orange,

4:05

all part of the central region, and then

4:08

this little darker area here up front is

4:12

the anterior fibromuscular stromal area.

4:15

Then we've got some preprostatic fat or retro

4:18

pubic fat, the so-called space of Retzius.

4:23

Let's go caudal or south to the middle of

4:26

the gland, right smack dab in the middle.

4:29

Well, now we get a much better

4:31

discrimination between the PZ and the TZ,

4:36

the central region.

4:38

So here's our PZ.

4:39

Let's draw the anatomic capsule,

4:43

which defines the central gland.

4:46

And let's draw the, sorry,

4:48

that's the surgical capsule.

4:49

Let's draw the anatomic capsule,

4:52

which is the boundary of the prostate.

4:55

So surgical capsule, anatomic capsule, PZ.

5:00

Ooh, that's pretty.

5:02

PZA, PCP, PCM.

5:06

In the central area of the prostate, we've

5:09

got mostly transitional zone, although

5:11

in the front, a little bit darker,

5:13

right there, anterior fibromuscular stroma, or AS.

5:19

We have a right AS and a left AS.

5:22

And we've got a transitional zone.

5:24

Ooh, I like orange for that.

5:26

And we'll include the periurethral

5:27

tissues in our transitional zone.

5:30

We'll color it in.

5:31

And we've got a TZA, okay?

5:34

And a TZ, I think they had a Z, and a TZP.

5:39

Oh, we're doing great.

5:41

Let's keep going.

5:42

Let's go down towards the apex.

5:45

Now we're down pretty low.

5:47

And the central region assumes a

5:49

much smaller anatomic configuration.

5:51

It's a little tougher for you to discern.

5:56

So I'm going to draw around the central

5:59

region down so low it's very small.

6:01

It's this area right here.

6:06

And then everything around it is peripheral zone.

6:10

It's much harder to discriminate down low on a 3D

6:13

than on a 2D, especially in this patient because

6:16

their peripheral region is a little bit darker.

6:20

And then I'm going to color in the central TZ,

6:26

and that little lentiform area, I covered it up

6:28

just a little bit, is right here in the front,

6:31

the anterior fibromuscular stroma, and you

6:35

would have anterior and posterior components

6:38

of the TZ and the PZ as we discussed before.

6:43

So now let's go to the coronals.

6:46

We'll start our coronal at the level of

6:48

the vas deferens and the seminal vesicles.

6:51

We'll watch them come into the

6:52

back of the prostate gland.

6:54

And then we'll get into the posterior

6:57

third of the gland, where we can clearly

6:59

discriminate the darker central region

7:03

from the more peripheral lighter region.

7:07

Now in most individuals, this area

7:09

is whiter, in fact white, on the T2.

7:12

Not as white as water, but whiter.

7:14

So let's draw.

7:16

Just for your eye, give you

7:17

a little bit of eye candy.

7:20

Everything above this is

7:21

going to be central region.

7:23

And closer to the midline is going

7:25

to be the central zone of the

7:27

central region, right about here.

7:30

And the rest of it we'll draw in as orange as TZ.

7:37

We're in the back of the gland.

7:38

Remember where we are.

7:39

Here we are in the back.

7:41

We got a lot of peripheral zone here.

7:44

How much?

7:44

About this much.

7:48

Quite a bit of peripheral zone.

7:49

Look how far down it goes.

7:52

It looks like a creature, doesn't it?

7:53

Two eyes, a nose, and a mouth,

7:57

and a funny-looking chin.

7:59

Let's keep going, shall we?

8:01

Let's go to the middle of the gland,

8:03

right, smack dab in the middle.

8:05

It gets a little bit tougher

8:07

to see the peripheral zone.

8:08

You know, in the center of the gland in

8:11

the coronal projection, you're looking

8:13

at a lot of central region tissue.

8:16

In fact, almost all of this

8:17

is central region tissue.

8:19

Let's draw it.

8:21

Let's make it orange.

8:21

Let's make all of it orange.

8:24

As we come forward, we don't

8:26

see a central zone anymore.

8:28

We see all the tissues of the central

8:30

region, the periurethral tissues,

8:32

which are a little bit brighter, and the rest

8:34

of the TZ, which is a little bit darker.

8:37

And we hardly see any peripheral zone.

8:39

It's very slit-like at this locus here.

8:43

In the middle of the gland from front to back.

8:46

Let's keep going forward, shall we?

8:49

Let's go all the way to the front.

8:53

And we are seeing the TZ here.

8:57

Let's draw it again in orange.

9:01

And we're gonna run smack dab into

9:03

the fibromuscular stroma in a second.

9:05

And now if I take that away, you can

9:07

see the tissues to the side, at least

9:10

on the right, are a little bit brighter.

9:13

Like here you can see it.

9:14

I'm going to draw over the PZ now.

9:18

Now look very carefully.

9:19

These tissues are a little bit

9:22

brighter than this tissue right here.

9:26

Let's keep going into the fibromuscular stroma.

9:30

Now we're all the way to the front.

9:31

That is fibromuscular stromal tissue.

9:33

That is also fibromuscular stromal tissue.

9:38

Let's go to the sagittal projection.

9:41

Let's go to the midline where

9:42

we see the urethral opening.

9:45

And now let's go off the midline.

9:46

Just slightly to one side or the other.

9:48

Right there.

9:49

Left.

9:49

Right, let's stay on the right.

9:52

Slightly darker, more nodular area.

9:55

Green is my favorite color for the central zone.

9:58

In the central region of the prostate is there.

10:02

The rest of this tissue right here,

10:04

which I'm now gonna color in in

10:06

orange, is gonna be transitional zone.

10:11

And in fact, even the central

10:13

zone is part of the central gland.

10:16

So where's the peripheral gland?

10:19

Makes this funny looking J shape right here.

10:23

Goes all the way around.

10:25

This dark lentiform area right here.

10:28

Lenticular looking.

10:29

The AS, or anterior fibromuscular stroma.

10:33

Now remember, the 3D is more for mapping.

10:35

The 2D is more for contrast.

10:38

See if we can get a little bit better

10:39

discrimination of the PZ and the central gland.

10:43

We do.

10:44

We'll make it even bigger on the sagittal.

10:46

Now you can see seminal vesicle.

10:50

I'm gonna make the seminal vesicle purple.

10:53

I don't know why; it just looks pretty.

10:57

And then off to the side, we have

10:59

the central zone, which is up here.

11:03

And then we have the transitional

11:05

zone, which is right here.

11:09

Color that in.

11:12

And this is all the central region of the gland.

11:15

And now we have the peripheral zone.

11:17

Now we can see our J, right?

11:21

There is our J.

11:25

We're off to the side.

11:26

I probably included a little bit of

11:27

the fibromuscular stroma in there.

11:29

Let's see if I can erase it with my pen.

11:31

That's what kind of talent I have.

11:32

Limited talent, but I did it.

11:34

And there's your fibromuscular stroma.

11:39

And then you would have a

11:41

PZP in the back, at the base.

11:45

At the mid, and then lower down,

11:47

towards the apex, and then you have a PZA.

11:51

And you'd have it apical and mid.

11:54

And that is how you would label the gland.

11:57

Now, to validate, even though it's on the 2D

12:00

vignette, to validate that we have a PIRADS 1,

12:04

let's look at our diffusion sequences.

12:08

Let's take a B value of 0, a B value of, say, 800.

12:14

Well, let's take 800.

12:16

800, and let's take a B value

12:18

of 1600, and let's scroll them.

12:22

The diffusion image is there for

12:24

the taking for the peripheral zone.

12:26

Here is your peripheral zone.

12:29

There's your central gland.

12:32

And here is your B value of 1600.

12:36

And if you have diffusion restriction,

12:37

something should be getting brighter.

12:40

It's not.

12:41

Little urethral tissue there, but it, it's not.

12:45

There's no mass present.

12:48

If you had diffusion restriction in

12:50

the peripheral zone, one of these areas

12:52

would be bright in the peripheral zone.

12:54

These are dots.

12:56

This is just pixelation.

12:58

So there is no greater than 3 millimeter to

13:03

5 millimeter mass in the peripheral zone with an

13:06

anatomic correlate that is diffusion restricted.

13:10

You're gonna see what some serious

13:12

diffusion restriction looks like.

13:14

When we go to PIRADS 4 and 5.

13:18

Let's look at our ADC map.

13:21

Our ADC map is looking for dark areas,

13:25

especially in the peripheral zone.

13:28

Do we have any?

13:29

Well, no, we don't.

13:31

We have a few dots and spots and pixels here

13:34

and there, but our peripheral zone has no

13:38

mass like, 3 to 5 millimeter or greater

13:41

hypointensities that correspond to diffusion weighted

13:44

hyper intensity that correspond to any

13:48

mass-like abnormality on the T2 weighted image.

13:51

So our PZ is clean.

13:54

We already looked at our T2 for the TZ.

14:00

T2, TZ.

14:02

Nothing on the T2.

14:04

No mass.

14:05

No ill-defined nodules.

14:07

No nodules that are invasive,

14:09

aggressive, crossing boundaries.

14:11

TZ clean.

14:13

PZ clean.

14:15

What about the dynamic contrast-enhanced MRI?

14:19

Let's take a look at that.

14:23

I'm gonna go two up for a minute.

14:26

Just to give you a little

14:27

more, a little more size.

14:32

We've got a mask on the left

14:35

and subtractions on the right.

14:36

Let's, let's scroll our mask, each

14:38

one of these about 10 seconds.

14:41

We're waiting for the contrast to arrive.

14:43

It's just coming in right now.

14:45

We see it in the femoral artery.

14:50

Just coming in.

14:52

And it's arrived in the prostate gland.

14:54

And it, there's some symmetric contrast.

14:57

Enhancement in the central region of

14:59

the prostate gland, around the urethra,

15:00

with a little septum in the center.

15:04

It's symmetric, it's not very intense,

15:08

and it is in the transitional zone of the gland.

15:12

So, enhancement doesn't in any way affect

15:16

the PIRADS1 designation in this case.

15:20

Diffusion negative, T2,

15:23

mass-like lesions in the TZ negative.

15:24

Let's keep going.

15:25

It washes in.

15:27

It gets brighter, and brighter,

15:30

and brighter, and the gland catches up to it.

15:33

And it's symmetric, and it's around the urethra.

15:36

It's just fine.

15:37

Now what about the subtractions?

15:40

Now we're getting into the

15:41

subtractions on the right.

15:42

Here they come.

15:43

This is subtraction phase one.

15:45

Here it is.

15:47

Symmetric central enhancement.

15:49

It gets brighter.

15:51

And brighter, as does the rest of the

15:52

gland and brighter it's washing in

15:54

and that's all just absolutely fine.

15:58

We also have a delayed T1 doesn't

16:01

have a tremendous amount of value,

16:03

doesn't really change anything.

16:05

But what is valuable is the pre-contrast T1,

16:08

because that's the one you use to look

16:10

at the peri-prostatic fat, the pre-prostatic

16:14

or retropubic space of reus, the rectal

16:18

prostatic fat, and the Denonvilliers' fascia.

16:21

You look at the fat around each neurovascular

16:24

bundle at five and, at five o'clock and

16:26

seven o'clock to make sure that nothing

16:28

has crossed over and invaded these.

16:31

You look at the dark signal intensity of

16:33

the anatomic capsule of the prostate gland.

16:36

You might look for lymphadenopathy,

16:39

solid nodes that are not tubular in the pelvis.

16:42

And all of these in this patient are negative.

16:44

Don't forget to look at the bladder and its

16:46

thickness, cellulation, trabeculation, etc.

16:49

And finally, check the heart.

16:51

The signal intensity of the bone marrow

16:54

looking for sclerotic bone lesions.

16:56

Patients with PIRADS 1,

16:58

no bone lesions, negative study.