0:00

Now let's look at our five-point scoring system,

0:03

that we use for reading, but in truth,

0:06

it's really a four-point system because nobody uses

0:10

spectroscopy for reading, imaging, scoring.

0:14

And in fact, many people, including our colleagues

0:16

in Germany, don't even use dynamic contrast

0:20

enhanced MRI for screening of the prostate.

0:25

And have found no difference between

0:27

the diagnostic study with DCE MRI,

0:30

dynamic contrast-enhanced MRI,

0:32

and the screening study that excludes it.

0:35

So, if you are doing a screen, who might be a

0:37

candidate for a screen that hasn't had a biopsy?

0:41

Because that's a question that's often asked.

0:42

The virgin prostate.

0:44

Somebody with BPH.

0:46

Maybe the prostate is gradually,

0:47

slowly getting bigger.

0:49

And the PSA is low, 4.5, certainly

0:52

under 10, and it's rising very slowly.

0:56

The patient isn't that symptomatic, otherwise.

0:59

And the patient has no strong family history

1:02

of carcinoma in the prostate, or in other

1:04

organs like the colon and the pancreas.

1:07

That would be a candidate.

1:09

For somebody that has not had a biopsy,

1:12

to have a screening MRI, looking for

1:14

areas of diffusion restriction, especially

1:16

in the peripheral zone, and morphologic

1:19

abnormalities on the T2-weighted image.

1:21

So, here is our T2-weighted image.

1:24

Performed with the cardiac external coil.

1:27

It is not endorectal, so there's been

1:29

nothing placed in this patient's butt.

1:32

The buttocks is collapsed because

1:34

they've had the proper prep tuned into

1:36

the vignette on prep if you need to.

1:39

It's fast.

1:40

It's inexpensive.

1:42

The patients like it a lot better when you

1:44

don't have to put anything in their rear end.

1:47

So this is the way to do both

1:49

screening and diagnostic MRI.

1:52

Now I've got some of the

1:53

parameters listed on the left.

1:54

I'm not going to read them off to you.

1:56

You can see the scan time.

1:58

You can read them for yourselves.

2:00

And this is an axial series of images.

2:04

Look at the overall slice thickness.

2:07

This is a

2:08

3.5 millimeter slice thickness.

2:09

So this is damage.

2:11

2D technique, but exquisite detail showing

2:15

you the peripheral prostate capsule.

2:18

We'll talk about the anatomy separately.

2:20

But I'm just showing it now

2:21

for protocol assessment.

2:22

And you would go up and down looking for what?

2:26

Looking for areas of mass like, confluent,

2:30

or round hypo intensity in the peripheral zone.

2:35

What would you be looking for in

2:36

the central zone on the prostate?

2:39

The T2-weighted MR, something akin to wax on,

2:43

wax off, something lentiform, something that

2:47

looks like you took a piece of charcoal and

2:49

started erasing the central and transitional

2:52

zones whose anatomy will be defined shortly.

2:55

So don't worry, we're on

2:57

to anatomy in a little bit.

2:59

Let's keep going on to the next

3:01

portion of the examination.

3:04

This is a T1-weighted image.

3:06

This actually doesn't come

3:08

into the scoring system.

3:10

However, you'll have a

3:12

T1-weighted image for a few reasons.

3:14

One, it's awfully nice to look at the

3:17

periprosthetic fat and see that it is clean.

3:21

It's also an excellent way

3:23

to depict bony metastases.

3:26

It's also an excellent way to look

3:28

for lymphadenopathy, the clean fat

3:32

around the posterolateral corners.

3:35

At 7 o'clock and 5 o'clock, with these small

3:38

tiny little dots at 7 o'clock and 5 o'clock

3:43

helps you clear the neurovascular bundle.

3:46

So if you lose that circumferential fatty ring,

3:50

then you have to worry, if you have a mass in the

3:52

prostate, about neurovascular bundle invasion.

3:58

So here is a coronal.

4:01

Now, not every, not every scan

4:03

needs to have a coronal projection.

4:06

Uh, in fact, if you're doing the

4:08

study three dimensionally, you can

4:11

reconstruct the coronal projection.

4:13

So this is an optional one to add to

4:15

your screen, to your diagnostic study.

4:18

You're probably gonna have a

4:19

coronal for lesion localization.

4:22

But not necessarily for the screen itself.

4:26

And in the coronal projection parameters shown

4:28

on the left, our abnormality on the T2,

4:32

which looked a little rectangular, I'll go back to

4:34

it for a minute, looks a little rectangular.

4:38

It looks a lot more round in the coronal

4:40

projection, and we're going to divide up the

4:43

prostate into a base, a mid, and an apex,

4:47

and that'll be a story for an anatomic day.

4:49

But at the base, on the viewer's left,

4:52

the patient's right, there is a round

4:55

mass in the PZ, or peripheral zone of the

4:58

prostate, where most of the cancers occur.

5:02

Here's your hyperintense PZ, with a

5:04

tumor growing straight out the top.

5:07

So in this case, the coronal projection.

5:10

Helps you localize the position of the tumor.

5:13

Although, if you're pretty advanced,

5:16

you wouldn't need to do that in the axial projection.

5:18

You'd be, you'd figure it out by looking

5:19

at the axials from top to bottom.

5:21

And you would know where you are anatomically.

5:25

If you want, you could also include a sagittal

5:28

T2-weighted image for further localization.

5:30

Although, for screening,

5:32

that wouldn't be necessary.

5:34

And again, if you have three-dimensional

5:35

imaging, you can reconstruct your sagittal,

5:38

you don't have to acquire it, and that gives

5:41

you extreme efficiency in performing the exam.

5:45

Then we've got diffusion-weighted imaging.

5:49

This is the second most important, if not

5:51

equally important, as part of the examination.

5:55

So what we'll do is we'll get a

5:56

baseline study, B0, in which the

6:00

diffusion gradients are turned off.

6:02

So it's basically a very, very fast,

6:04

uh, Echo planar type, T2-weighted image.

6:08

And then we start turning up the dial.

6:11

We turn up the heat.

6:13

That's what elevating the B value does.

6:15

It makes the gradients tighter, higher.

6:19

It shows with greater sensitivity

6:21

diffusion restriction.

6:23

And as we go from, say, 0 to 400 to 800 to

6:27

1200 to 1600, an area that diffusion restricts

6:30

gets brighter and brighter and brighter.

6:34

As opposed to, say, an area that has high T2, like

6:37

this one, gets darker as you dial up the B value.

6:43

Now this is only a B700, but we like to go to

6:46

a B value of at least 1400 and preferably 1600.

6:52

What's the least B value that I will work with?

6:55

154 00:06:56,590 --> 00:06:58,409 1200 works on most scanners.

6:59

1400, very acceptable.

7:01

1600, ideal.

7:04

So this area right here, which didn't look like

7:06

much of anything, oh, it's diffusion restricting.

7:09

It has a lentiform or oval shape.

7:14

These two stalwarts of the prostate MRI, the T2

7:21

Spin Echo, Fast Spin Echo, 2D or 3D, and the diffusion

7:24

weighted image are the guts of the prostate exam.

7:28

You'll then take this information and you will

7:32

convert it. As we'll see in a few moments, into

7:35

a parametric map, a so-called a DC map, and the

7:39

bright area that you saw in the left gland.

7:43

Your right will now appear dark and we'll

7:46

explain to you why that is in a moment.

7:50

Another component of the MRI, less important than

7:54

the ones you've already seen, less important than

7:56

the T2, the diffusion, and the yet-to-be-shown.

7:59

A DC map is the DCE-MRI.

8:05

The Dynamic Contrast-Enhanced MRI.

8:08

Its main value is in helping you further

8:11

determine how aggressive a lesion is.

8:14

If you see an area that immediately enhances

8:18

in the first seven seconds after contrast

8:21

administration, on the very first arrival of the

8:23

contrast into the adjacent vessels nearby, odds

8:27

are you've got at least eight, nine, or ten.

8:31

And especially if this intensity starts to smear.

8:36

Like cream cheese on a bagel, that means

8:39

that it's washing out, and that's another

8:42

negative, ominous sign that you're

8:45

dealing with a Gleason 8, 9, or 10.

8:49

Other signs that you're dealing with a high

8:51

grade Gleason lesion are size, bulkiness, extreme

8:56

diffusion restriction, very low signal on the

9:00

ADC map, broad areas of abutment of the capsule.

9:05

All signs of something that is more aggressive.

9:09

So here we've got a combination of the dynamic

9:13

contrast-enhanced MRI in a different patient

9:16

and a T2-weighted image in a different patient.

9:20

This is cancer, this is an aggressive cancer.

9:23

So we're showing you two aspects of the exam.

9:26

Now here is something else that you

9:29

can do as an option and that is the

9:33

three-dimensional T1-weighted image.

9:35

I don't routinely perform this,

9:37

but if you're looking for very small nodes, or you

9:40

really want to drill into the neurovascular

9:43

bundle and you're not sure if you see the bundle

9:46

around the edges at 5 and 7 o'clock around the

9:48

prostate, you may opt for one-millimeter axial

9:51

slices using some form of T1 appearing GRE.

9:54

I don't do this routinely.

9:56

You can also reformat or reconstruct it.

9:59

Now let me show you the ADC map, which is the

10:03

second most important part of the examination,

10:06

or perhaps even the most important part, and it's

10:10

derived from the diffusion-weighted sequences.

10:13

So diffusion and ADC map,

10:15

for you beginners, go hand in hand.

10:17

Diffusion makes the map.

10:19

So what is the map?

10:20

The map is a pixel-by-pixel blow, in other words,

10:25

a blow-by-blow, a blow-by-blow description,

10:28

that's hard to say, of the velocity of flow blow.

10:32

In each single pixel on the image.

10:36

So if you have diffusion

10:37

restriction, what's the velocity?

10:41

Lower, right?

10:41

Because it's not moving.

10:42

It's restricted.

10:43

So the lower the velocity,

10:46

the lower the intensity on the ADC map.

10:50

So what's bright on diffusion?

10:52

Dark on the map.

10:55

So that's how you do it.

10:57

So you've got a mass on the

11:00

T2 weighted image in the peripheral zone.

11:03

You've got diffusion restriction

11:04

that's bright on the diffusion image.

11:07

You've got low signal intensity

11:11

on the parametric ADC map.

11:13

And if you choose to do dynamic

11:16

contrast-enhanced MRI, and the lesion

11:19

is aggressive, it will enhance early.

11:22

And therefore be bright on this color

11:26

flow map of dynamic contrast-enhanced MRI.

11:31

So that's the exam.

11:32

Notice I did not show you a spectroscopy.

11:35

I also said that the DCE MRI does not have

11:39

to be performed in every single individual.

11:41

It's going to be elective and selected

11:44

by you based on judgment and the

11:46

scenario, but you must have the T2, the

11:49

diffusion, and the ADC parametric map.