0:01

Now we're going to illustrate the value,

0:04

the power, the integrity of the 3D gradient echo,

0:08

but not just any gradient echo, not field

0:11

echo, not simple gradient echo, not GRASS, not

0:14

FLASH, not FISP, but additive gradient echo

0:18

imaging known as ADDIGE, MERGE, MEDIC, MFFE.

0:24

Very powerful signal-to-noise sequences

0:27

that allow for very thin slices.

0:29

In this case, we've done

0:31

1.7-millimeter cuts, contiguous,

0:34

no separation, to allow for reconstruction.

0:37

Although, typically, I like to

0:38

have about 50% overlap.

0:40

How thin can you go with these pulsing sequences?

0:43

You can go down to about 0.5 millimeters.

0:48

So, these are

0:48

1.7s contiguous, acquired in the sagittal

0:51

projection using gradient echo, which,

0:54

which you know is powerful for cartilage,

0:59

for the detection of bodies, and for tendons.

1:02

It's also a very good supplementary sequence

1:06

because of its high spatial detail for ligaments.

1:09

So we're scrolling along and we see,

1:11

look at that short plantar ligament.

1:12

Oh, that is beautiful.

1:15

We see the plantar fascia.

1:16

Oh, that's beautiful.

1:18

We're also besot with magic angle

1:20

effect on gradient echo imaging.

1:24

But there's a method to my madness here.

1:26

So if I click this upper button,

1:27

which I've already done, I can

1:29

take this and reproduce a coronal.

1:32

It's a straight coronal, but I

1:35

don't want a straight coronal.

1:37

I would like a paracoronal.

1:39

I want a coronal that shows me

1:42

the critical ligament in the foot.

1:47

Now granted, there are critical ligaments in

1:48

the ankle, and we're going to talk about those

1:50

later on, especially when we get to the ankle.

1:52

But in the foot, the critical

1:54

ligament is the Lisfranc ligament.

1:56

So I'm going to angle absolutely parallel to

1:59

the long axis of the foot and plantar flexion.

2:02

Now, let's scroll.

2:05

There's our navicular for orientation.

2:07

Let's find our medial cuneiform.

2:09

That's easy, right there.

2:11

We find our medial cuneiform.

2:13

We find the connection of

2:15

C1, medial cuneiform, to M2.

2:17

And we are looking at the Lisfranc ligament

2:20

complex, of which there are plantar components.

2:24

There they are.

2:25

Out of which there are middle components.

2:28

There they are.

2:30

And they will be discussed in detail

2:32

when we have Lisfranc ligament injuries.

2:35

So you can do that with just about any ligament.

2:38

For instance, here are some

2:39

intercuneiform ligaments.

2:42

Wow.

2:43

Now let's go over to the axial projection.

2:48

This is straight axial.

2:49

But you know what?

2:51

I don't really want a straight axial.

2:53

I want a curved axial.

2:55

Because my peroneus brevis,

2:57

and longus are curving.

3:00

So let's curve, shall we?

3:04

Let's make them perpendicular

3:05

to the peroneus longus.

3:08

There's the peroneus longus.

3:09

Let's scroll it.

3:10

We're perpendicular to it.

3:12

It's beautiful, and then it turns gray.

3:16

Is that gray magic angle effect, or is it real?

3:18

It's real.

3:20

But that will be another subject.

3:23

Which, by the way, we've already

3:24

covered in the magic angle effect,

3:25

so go back and look at that vignette.

3:28

Now let's go back up to the peroneus

3:31

brevis, and let's angle absolutely

3:34

perpendicular to the brevis.

3:36

And we've got it.

3:38

Now, when the foot is plantar flexed,

3:40

one caveat, the tendons, especially the peroneus

3:43

brevis, is going to be pushed or slammed up

3:46

against the back of the malleolus and flattened.

3:50

And this sometimes will obscure tears.

3:52

But if you have a tear, you will see a very

3:55

well-defined, bright split that separates the tendon

4:00

in two, and it will look something like this.

4:03

You'll see one limb of the tendon, the other limb

4:05

of the tendon, and right in the very center of

4:08

it will be some high signal intensity that is

4:11

well-defined, separating those two components.

4:14

We don't have that here.

4:16

We have an intact, compressed tendon.

4:19

This illustrates the strength of gradient echo

4:24

imaging with proper reconstruction and proper

4:28

creativity on the part of the imager to come

4:31

up with correct and proper diagnoses on some

4:35

very small structures, such as ligaments.

4:37

The axial projection would also be a projection

4:40

to look at the anterior tib-fib ligament.

4:43

It'll be the projection to look at

4:44

the anterior talofibular ligament.

4:46

But usually we like it to be

4:48

a little more perpendicular.

4:49

So let's see if we can get it a

4:50

little more perpendicular this way.

4:53

And let's see if we can find and define

4:55

the anterior talofibular ligament.

4:58

Not so much.

4:59

And the reason is too much swelling.

5:02

So we would go back to our T2.

5:05

Define a ligament, and believe me, it's there.

5:08

It's on a prior vignette.

5:10

It's perfect.

5:11

It's thin.

5:11

It's smooth.

5:12

So a little too much hyperintensity

5:14

present here to actually see the ligament

5:18

with this particular pulsing sequence,

5:20

even though it is a thin section.

5:22

So, also illustrating that you have to

5:24

go back and forth between the proper

5:26

sequences to get the right answer.