0:02

weighted imaging, DWI, and both the PZ,

0:07

peripheral zone, and transitional zone.

0:10

So in DWI, you, the operator, can control

0:13

the horizontal and the vertical and the

0:15

intensity of diffusion restriction detection.

0:19

So a low B-value would mean your gradients for

0:22

diffusion restriction detection are not turned on.

0:25

It's basically a very rapid, echo-planar T2 image.

0:30

It's kind of your baseline.

0:32

As you turn the B-value up, let's take an

0:34

intermediate B-value of 800, your ability

0:38

to detect diffusion restriction goes up.

0:42

And the higher you make it, say 1600, The

0:45

more that detection sensitivity intensifies

0:49

and another thing happened, if there is

0:51

diffusion restriction in a bright lesion

0:53

here, then the intensity of that object gets

0:58

higher at B 800 and even higher at B 1600.

1:03

In that we'll make two arrows and three arrows.

1:07

What if this was simply just

1:09

an object that's bright?

1:10

But it's not diffusion restricted.

1:12

In other words, it's bright on T2,

1:14

but there's no diffusion restriction.

1:16

And you're probably asking, well,

1:18

what causes diffusion restriction?

1:20

I'll answer that in one minute.

1:22

But if it's just T2 prolongation, but not

1:26

diffusion restriction, the signal will

1:28

go down as you go to the higher B-values.

1:33

diffusion restriction?

1:35

On the brain, necrotization, say, heroin,

1:40

uh, heroin toxicity of the brain, that

1:43

doesn't occur in the prostate gland.

1:45

So necrotization is not a common cause.

1:47

It can occur, but it's not a common cause

1:50

of diffusion restriction in the prostate.

1:52

Cellularity with paucity of cytoplasm

1:55

and or firmness of an object,

1:58

desmoplasia, that is a cause of diffusion

2:01

restriction in the prostate gland.

2:04

Cell membrane injury or death.

2:07

That is not a common cause of

2:09

diffusion restriction in the prostate.

2:11

But it is in the brain where you have a cell.

2:14

The cell membrane is injured.

2:16

Fluid rushes in through that injury

2:18

and gets stuck inside the cell.

2:20

That's what happens in a stroke.

2:24

And finally, the last cause of diffusion

2:26

restriction is high viscosity or V.

2:30

Where do you have high viscosity?

2:32

An abscess.

2:34

So if you have a prostate abscess, it could.

2:37

Diffusion restrict, but it's not a tumor.

2:40

Therefore, diffusion restriction all by itself is

2:44

not pathognomonic of a tumor, but I will say this.

2:47

The more intense the diffusion restriction becomes

2:50

as you go up, the more likely it is to be a tumor.

2:55

So not only are we going to assess for

2:57

diffusion restriction, we're going to assess

3:00

the intensity of the signal change from

3:03

moment to moment, from B-value to B-value.

3:05

Some people may acquire 5, 6, or even 7 B-values.

3:09

And there's another part of

3:11

the diffusion-weighted image.

3:13

And that is the calculated portion of the image.

3:16

The so-called ADC map.

3:20

This parametric map of the prostate gland

3:24

is composed pixel by pixel of the velocity

3:28

of movement inside the prostate gland.

3:31

So if we take one pixel, and we say

3:34

that the velocity is 10, not going to

3:36

give any units to it, that will be 10.

3:39

Restricted, low velocity, therefore

3:42

the signal will be darker.

3:44

We'll make it blue.

3:47

Whereas if the velocity of a group of

3:49

pixels, we'll take a bigger group now, is

3:52

higher, let's say a few pixels together,

3:56

if their velocity is higher, let's say 50,

3:59

then those pixels are going to be brighter.

4:02

So high velocity means no diffusion restriction.

4:06

Low velocity means diffusion restriction.

4:10

What you need to grasp is

4:11

this is the inversion of that.

4:14

So what's bright over here Because

4:16

of diffusion restriction, on the

4:18

calculated map will be dark over here.

4:22

So on B1600, getting brighter, the

4:25

more well-defined and darker it is,

4:27

the more ominous it is on the ADC map.

4:30

Or said another way, darker equals

4:33

brighter, brighter equals darker.

4:37

Now, let's look at the scoring system.

4:41

So we've got one, no abnormality on ADC, and the

4:45

high B-value DWI, or the 1400 or 1600 B-value MRI.

4:50

Number two.

4:51

Indistinct, hypo-intensity, only seen

4:54

on the ADC map, for the parametric map

4:58

is actually more sensitive than the

5:00

acquired diffusion-weighted images.

5:03

Number three, focal, mildly or moderately

5:07

hypo-intense on the ADC map, and ISO in the to

5:11

mildly hyper-intense on the high B-value DWI.

5:16

What this is telling you is, your

5:17

ADC shows more than your DWI.

5:21

It's more sensitive.

5:23

So dark on ADC, kind of ill-defined,

5:27

tweener in the middle on DWI.

5:30

Number four.

5:31

Focal.

5:32

Marked.

5:33

Hypo-intensity on ADC, and markedly

5:36

hyper-intense as the B-value goes up.

5:39

When you're at 1400 or 1600, very bright.

5:42

But the object, less than 1.

5:44

5 centimeters in size.

5:46

And 5, the same as 4, but greater than 1.

5:49

5 centimeters in size, approaching 2 centimeters.

5:54

So, a 3 is a tweener.

5:57

A 3 has hypo-intensity on the ADC, but not

6:00

much impressive on the high B-value DWI.

6:06

The rest is very self-explanatory.

6:09

Let's move on, shall we?