0:00

Let's take on the anatomy of the prostate

0:03

in the sagittal projection, comparing

0:05

it with the coronal projection and using

0:07

the coronal projection for landmarks.

0:10

Now you can see by my cross-reference line that

0:12

I'm right smack dab in the middle of the prostate,

0:15

and this little opening is the opening between the

0:18

bladder and the prostate gland via the urethra.

0:23

So if you can fantasize with me a little bit,

0:25

since we don't have any fluid in the urethra,

0:28

you can see the urethral opening right here.

0:30

And it kind of comes down

0:31

and then angulates forward.

0:33

We're going to see that better

0:34

on some other, uh, MR examples.

0:38

Now since we're in the, the center of the

0:40

gland, we're not far enough posterior,

0:43

we only see the central gland portion.

0:47

And yes, there is some hyperintensity

0:50

on the coronal image, which just

0:52

consists of secretory material.

0:55

Uh, that's a good sign.

0:56

That, that is a sign that most likely you do not

0:59

have a prostate carcinoma in that, that locus.

1:03

Now there is a mucinous adenocarcinoma of the

1:06

prostate, but fortunately it's very unusual.

1:09

In fact, it's very rare, and it will

1:11

demonstrate bright signal intensity,

1:12

but a much more aggressive character.

1:14

And they're usually large

1:16

at presentation.

1:18

Let's take away our line for a moment.

1:20

And I'd like to move towards the front.

1:22

And the front of the gland is darker.

1:26

And that's because the front of the gland

1:28

consists of the anterior fibromuscular stroma.

1:32

Remember the word fibro, which stands for fibrous.

1:36

You should know that fibrous tissue on MR is dark.

1:39

So this area is pretty dark.

1:41

We can see an average volume with the base

1:43

of the bladder. Here it is right here.

1:44

It's pretty thin in this patient, and

1:47

then posterior to that is going to be the

1:51

central gland portion of the prostate.

1:54

So what's in the central gland?

1:57

The transitional zone and the central zone.

2:01

Where do you find the central zone?

2:05

Posterosuperiorly.

2:07

So if I had to draw for you the position

2:09

of the central zone, and if the central

2:11

zone was big, where is it going to be big?

2:13

Right here, in the posterosuperior quadrant.

2:17

And when it gets really big, it can sometimes get

2:19

kind of fluffy and look like a piece of broccoli.

2:22

And it can stick up into the base of the bladder.

2:26

Now staying right here for a moment, let's

2:28

draw in the fibromuscular zone with a

2:32

different color so we don't get confused.

2:35

And then posterior to the fibromuscular

2:37

zone, we've got the transitional zone

2:41

which is part of the central gland.

2:43

Let's make the transitional zone,

2:45

oh, let's, let's make it green.

2:49

So we've made it green and I'm coloring

2:50

in the transitional zone for you.

2:53

It's pretty big in this

2:54

patient. He's 62 years old.

2:56

But you've seen that I have left out

2:58

an area that I haven't colored in.

3:02

And what is that?

3:03

That's the periurethral zone.

3:07

And you can actually fantasize that it's there.

3:10

This little white slit right here.

3:12

That then curves forward, that's the urethra.

3:15

So that gray tissue right around it that comes

3:18

from this locus to that locus on a straight

3:20

line and then bends, that's your urethra.

3:24

Surrounding it is the periurethral tissue.

3:27

So we'll give that another color.

3:29

Oh, let's go with something, uh,

3:32

let's go with something blue.

3:34

So I'm gonna cover up the urethra now.

3:37

I'm behind it.

3:38

I'm in front of it.

3:40

And now I'm covering it up, and

3:42

then it makes an angle down.

3:43

So that's your periurethral zone, which

3:45

is located within the central gland, which

3:48

is located within the transitional zone.

3:52

So within the central gland, we've

3:53

got the periurethral zone, the

3:55

transitional zone, and the central zone.

3:59

In front, the fibromuscular stroma.

4:02

So you might ask, well, where,

4:03

where's the peripheral zone?

4:06

Well, we're right in the midline, so the

4:08

peripheral zone is an envelope, right?

4:10

It's around the outside, that's

4:11

why it's called peripheral zone.

4:14

So we've got to get more peripheral.

4:16

If we go out to the side, to the extreme

4:18

side, we run into the left peripheral zone.

4:21

The left PZ.

4:22

If we go the other way, we run into the right PZ.

4:25

And look at how it makes a J shape,

4:27

or a hook, as it faces anteriorly.

4:30

It does that on both sides, but it's a

4:31

little easier to see on the right side.

4:33

And look at how it goes down towards the apex.

4:37

And then curls inward.

4:39

So these are areas that have

4:40

to undergo careful inspection.

4:42

Because now you're near, now you're

4:44

near the anterior fibromuscular zone.

4:48

And what's the signal of the fibromuscular zone?

4:51

What's the signal of a cancer?

4:52

Charcoal.

4:53

Dark.

4:54

So you could confuse the fibromuscular

4:57

zone, anteriorly, and down low

4:59

fibromuscular with a cancer and vice versa.

5:03

So how are you going to tell?

5:05

Diffusion imaging and the ADC

5:07

map, which are going to help you.

5:10

So let's keep going and still

5:12

focus on the peripheral zone.

5:14

We said the peripheral zone is an envelope.

5:17

We see the separation of the peripheral

5:19

zone on the sagittal from the central

5:21

gland or peripheral gland from the

5:23

central gland by the surgical capsule.

5:26

We also see the anatomic capsule.

5:28

We also see the right SV, right

5:30

seminal vesicle, and ductus deferens.

5:33

There it is.

5:34

Ooh, that's pretty.

5:35

And then on the other side,

5:36

the left seminal vesicle.

5:38

Ductus deferens a little harder to

5:40

see on this side, but right there.

5:42

That little white slit.

5:45

Some other key structures.

5:48

This black structure right here represents

5:51

a combination of the volume averaged

5:54

denom Ville a recto prostatic fascia

5:57

and the peripheral anatomic capsule.

6:01

In the front, we have the pre prostatic

6:04

space of Reteus, or the puboprostatic space.

6:09

Bladder up high, looking at thickness,

6:12

cellulation, trabeculation,

6:14

diverticulation, and degree of dilatation.

6:19

We've already outlined for you the urethra.

6:22

And just for giggles, let's go

6:25

back to the coronal projection.

6:27

And let's, let's go a little bit more posteriorly.

6:30

So we can see the peripheral zone off to the side.

6:33

And let's go to the area of the seminal vesicles.

6:36

So that would be peripheral zone.

6:37

Now let's work our way forward.

6:40

And we're posterior, right?

6:41

We're in the back, seminal vesicles.

6:43

We're posterior.

6:44

So what are we looking at posteriorly?

6:47

We're looking at central gland.

6:49

But posterosuperior, in the upper

6:53

posterior quadrant, is the CZ.

6:57

The central zone of the central gland.

6:59

So where is that?

7:01

Right here, and right here.

7:04

Where is it sagittally?

7:05

Right back here.

7:07

And as you come forward, let's

7:09

come forward a little bit.

7:12

Still a little bit of CZ on each side.

7:14

Let's draw it again.

7:15

So you're gonna have CZ here, and here.

7:20

Right in that spot, posterior superior quadrant.

7:22

And the rest of it is gonna be transitional zone.

7:26

As we drew in the sagittal projection.

7:28

So let's color in the, the TZ.

7:31

Here's some TZ.

7:34

In the midline's gonna be your urethra.

7:36

And so we have your urethra

7:38

with your periurethral plexus.

7:40

This time we'll make it, uh, purple.

7:44

And there you have it.

7:45

Now I could have colored in a little

7:46

Prostate Anatomy on MRI in the Sagittal Projection

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