0:00

This is our fourth vignette discussing sequences

0:04

and we're going to throw all the sequences

0:05

at you so that you have a very deep bench,

0:08

deep knowledge of what sequences do what.

0:12

And on the far left is a T1

0:14

spin echo with fat suppression.

0:18

A lot of practitioners use this

0:21

after the arthrogram to highlight

0:23

the difference between the contrast

0:26

and the surrounding bone and labrum.

0:29

I personally.

0:30

Do not prefer this sequence.

0:33

When you're looking for intra-substance

0:35

labral pathology, it doesn't do a tremendous

0:39

job unless you have cystic change.

0:43

I prefer the proton density fat

0:47

suppression sequence, or the

0:49

standard T1 without fat suppression.

0:54

This axial projection, which by the way has

0:57

a tear that is through and through, does

1:00

not demonstrate the tear very adequately.

1:03

Let's scroll it from top and keep going

1:06

down where there is a tear right here.

1:08

We are right now through the

1:09

very tear, yet we don't see it.

1:13

Now perhaps, the sequence, which is greater

1:17

than three millimeters, is a little too thick.

1:20

But the tear is also very tiny.

1:23

So if you're going to perform axial imaging,

1:26

For labral pathology, I would strongly urge you

1:29

to consider three-dimensional isotropic imaging

1:33

whether you put contrast in the joint or not.

1:36

I'm showing this T1 fat suppression because it

1:39

happens to be a fan favorite, but it is limited.

1:43

Now, does it show the tear?

1:44

Yes, indirectly it does.

1:47

And here it is, right there.

1:49

That paralabral cyst tells

1:51

you that there's a tear.

1:52

Now, here's a problem.

1:54

How do you know that isn't the little

1:55

bit of contrast that extravasated?

1:58

You don't know because you've already

1:59

put the contrast in the joint.

2:02

So that's another potential limitation of

2:04

only performing contrast arthrographic MRI.

2:09

You don't know whether signals are

2:11

primary or secondary to the injection.

2:13

And identifying these primary abnormalities

2:17

like paralabral cysts and swelling and

2:20

inflammation is so important to characterizing

2:24

the importance of the abnormality.

2:26

Let's move over to these two.

2:28

These are two orthogonal coronal sequences.

2:34

In other words, they're straight anterior

2:36

to posterior, which is just fine.

2:39

But as we get more advanced, coming up to the

2:43

next vignette, coming to a theater near you,

2:45

you're going to see oblique coronals, and

2:48

oblique axials, and radials, and how they can

2:52

augment the diagnosis of labral pathology.

2:55

But even with orthogonals, the T1 image,

2:59

with contrast in the joint, shows a through

3:02

and through fissure-like vertical tear right

3:06

at the acetabulolabral and hyaline labral

3:10

junction, one of the more common types of tears.

3:14

And we didn't see it very well in

3:16

the axial orthogonal projection.

3:18

We see that the capsule is tightly

3:20

adherent to the lateral aspect of

3:23

the acetabulum on both sequences.

3:26

But I would have to admit that the tear is

3:28

a little more easily visualized on the T1

3:31

weighted image than it is on the PD spur.

3:35

Now, what would I recommend you choose?

3:38

I think for the post-arthrographic

3:41

image, it is really your choice.

3:45

The proton density fat suppression does

3:48

a better job at showing inflammation

3:50

and edema in the bone marrow as a sign,

3:53

as an indirect sign that that

3:56

labral pathology is causing symptoms.

3:59

For many adults have labral

4:00

pathology that's asymptomatic.

4:02

On the other hand, in my opinion, the

4:05

actual visualization of the tear in

4:07

the cartilage itself is a little easier

4:10

to see on the T1 spin echo image after

4:14

contrast is injected into the joint.

4:17

Some of you who are newer to MRI may

4:20

choose to do both for the two reasons

4:23

that we have already articulated.

4:26

So, when we move on to the next sequences,

4:29

we're going to look at some of these

4:31

sequences, but with different angulations

4:33

and projections, and also some three

4:35

dimensional thin-section imaging.

4:38

Thanks.