0:00

Alright, let's talk about some prostate anatomy

0:04

with these, uh, elegant series of diagrams.

0:07

And we're going to layer on different portions

0:09

of the, of the gland as we move forward.

0:11

So we started out here in yellow with the urethra.

0:15

And we'll break the urethra down later on into

0:17

its individual sub-segments and show you the

0:20

urogenital diaphragm, which would be here.

0:23

So, in your mind's eye, this would be inferior

0:26

or caudal, and this would be superior or cranial.

0:31

So the urethra is yellow, we've got the

0:33

expanded verumontanum and then the

0:36

urethra continues on up into the bladder.

0:40

We've also got these two purple structures,

0:42

the ductus deferens, which leads to the seminal

0:46

vesicles, and the seminal vesicles will be

0:49

located posterior superior to the prostate gland.

0:53

Uh, they're secreting organs so

0:55

they contain secretory material.

0:58

Although, after ejaculation, they will empty.

1:00

So, some people suggest that you not do

1:03

prostate MRI within one week after ejaculation.

1:06

That's a lot to ask.

1:07

Uh, however, as you get older, uh, these

1:10

may desiccate or dry out and have

1:13

less secretory material inside them.

1:15

So there's a lot of variability regarding the

1:17

signal in these glands, as we'll see later.

1:20

And that could be a potential

1:21

pitfall and source of confusion.

1:25

Now let's move on to another section, the

1:29

transitional zone, and the transitional

1:32

zone is part of the central gland.

1:36

So this is a little bit confusing.

1:37

Let's really kind of drill down into

1:39

this with a little more granularity.

1:41

The central gland consists of the central

1:45

zone and the transitional zone together.

1:50

So, often, we don't make a

1:52

distinction between the two.

1:54

We'll often just call disease in these locations.

1:58

Within the central gland, the central zone.

2:02

Even though the central gland

2:04

is composed of two components.

2:07

The transitional zone, and one that's located

2:10

more posterior and superior, the central zone.

2:15

Now the central zone can be, can be pretty big.

2:18

Varies in size, and both of these will

2:22

increase in size with advancing age.

2:26

And, in fact, they can get so big that

2:27

they can push out on the remainder of the

2:30

anatomy of the gland and, uh, in some ways

2:33

obscure the peripheral aspect of the gland.

2:36

Now, the peripheral aspect of the gland

2:38

is extremely important because that's

2:40

where 70 percent of all the cancers occur.

2:43

They're easier to identify in this

2:45

region, as we'll see later on.

2:47

And the criteria for identifying disease in the

2:50

central gland, which consists of the central

2:53

zone and transitional zone, a bit tougher.

2:57

Let's keep going, shall we?

2:59

The next layer that we're going

3:01

to put in is the peripheral zone,

3:03

and it's kind of like an envelope.

3:06

Now, notice that the peripheral zone

3:08

has a very distal, apical component.

3:12

So tumors that exist around here can have

3:15

not only a big impact on the urethra, but

3:18

they can also be hard to reach, hard to

3:21

see, a little more challenging to biopsy.

3:26

This envelope goes all the way around the right

3:28

side and the left side of the central gland.

3:32

It'll scoop around back of the central

3:35

gland and you're going to get a much

3:37

better appreciation for this when we

3:39

look at it with cross-sectional anatomy.

3:42

But I think this three-dimensional

3:44

anatomic diagram does it justice.

3:47

The next section is the

3:48

anterior fibromuscular stroma.

3:51

Which is fairly symmetric, it's

3:53

thin, it's on the right and left

3:55

side of the gland, and it's anterior.

3:59

It has a fairly long apical extension, inferiorly.

4:05

And because prostate carcinoma is dark,

4:08

and the fibromuscular stroma is dark,

4:11

this is where the diffusion-weighted image

4:13

is really important and really shines.

4:15

Because the cancer will diffusion restrict.

4:18

And the anterior fibromuscular

4:19

stroma will not restrict.

4:22

Not only is it anterior, it's composed of fibrous

4:25

tissue, and fibrous tissue is dark, cancer

4:29

is dark, so this could be a little bit of a

4:31

conundrum and a potential pitfall if you don't

4:34

pay attention to the diffusion-weighted image.

4:39

The fibromuscular stroma in the anterior

4:41

portion of the gland, somewhat pancake-shaped

4:44

and relatively symmetric from side to side.