0:00

Wanted to show you an example here.

0:02

Studied with conventional radiography

0:05

and CT scanning

0:06

of bilateral symmetrical changes involving

0:09

the sacroiliac joint.

0:11

Note that the CT shows better than the

0:14

conventional radiography.

0:15

The surface irregularity of ankylosing spondylitis

0:20

with sacroiliac joint involvement.

0:22

This is bilateral, it's not quite symmetrical, okay,

0:27

but it's bilateral.

0:28

And note the dominant involvement of the ileum.

0:34

To show you some examples of MR imaging used

0:37

to diagnose sacroiliitis

0:39

with T one weighted images on your left,

0:42

stir images on your right.

0:43

Here's one example, and again,

0:46

although you can pick up the erosive abnormality,

0:49

it's the inflammatory findings with a high signal

0:52

on the fluid sensitive sequences that are most helpful.

0:56

And another example here

0:59

showing you again on the fluid sensitive sequence on the

1:02

right, a stir sequence,

1:04

how the inflammatory changes can be easily picked up.

1:10

One further example, this one not as dramatic shown

1:13

with MR on the left

1:15

and CT dominant involvement of the anterior aspect

1:19

of the sacroiliac joint.

1:21

Now this is the pattern I'm most used to seeing,

1:24

where the anterior aspect

1:25

of the joint is more involved than the posterior aspect,

1:28

but there are exceptions to the rule

1:31

where in fact it'll be the posterior involvement

1:33

that will dominate.

1:37

Now one of the findings pointed out in the later stages

1:40

of ankylosing spondylitis, the quiescent stages is

1:44

what is called backfill of ero erosions with

1:50

the, uh, metaplasia into fat.

1:52

And so if you look at this particular example,

1:55

this is the initial uh, image

1:59

T one weighted here five years later,

2:02

initially we can see low signal.

2:04

Then you can see here five years later, all the fat

2:09

that has now replaced the abnormal bone on both sides

2:12

of the joint leading in fact, even to fat crossing

2:17

the S sacroiliac joint.

2:19

Here's another beautiful example showing you

2:21

that in a late stage of ankylosing spondylitis,

2:25

this is fatty metaplasia bright signal on the T one

2:29

low signal on the stir.

2:31

And you can see in this particular patient enthesitis

2:36

with involvement of the issue tuberosity.

2:41

Now, intraarticular fluid

2:44

may occur in normal persons shown at the top right here,

2:48

but it tends to be a small amount.

2:51

Large amounts of fluid can be a sign of sacroiliitis

2:56

as shown in the bottom image, particularly on

2:58

The fluid sensitive sequence.

3:01

And here's another example showing you a lot of joint fluid.

3:05

Generally when you see fluid to this degree

3:08

or amount, you should think of an underlying disease such

3:12

as s sacroiliitis.

3:14

I think R is particularly useful in following patients

3:18

with sacroiliitis during various types of therapy.

3:22

And indeed you can see here, again,

3:24

taken from the literature, the result of therapy

3:28

over 24 weeks with remarkable improvement in the image.

3:34

Now, just to complete our story of ankylosing spondylitis,

3:39

I wanted to just show you a little bit about

3:42

what we see in the spine, realizing

3:44

that this is a lecture on the sacroiliac joints,

3:47

but if we're talking about ankylosing spondylitis

3:50

or the spondyloarthropathies, we have to remember

3:53

that the spine is a typical target site

3:57

and especially the disco over vertebral uh, junction.

4:01

One of the earliest findings we see

4:04

represents inflammatory changes occurring at the corners

4:08

of the vertebral body.

4:09

We call this the shiny corner sign.

4:12

This is what it looks like in a, uh, specimen.

4:15

Here you can see it radiographically.

4:17

This is the Roman lesion.

4:20

Easy to remember are for rim, vertebral rim being involved.

4:25

Over a period of time owing to both erosion

4:28

and bone production, you will see squaring

4:31

of the anterior surfaces of the vertebral bodies.

4:35

You can study the OMO lesion with MR imaging

4:39

and early on, as shown in this particular stir image,

4:43

you're gonna see abnormal high signal

4:46

representing inflammatory change.

4:48

Later on, those corn, those corners

4:51

of the vertebral body may show fat infiltration,

4:55

fatty metaplasia

4:56

with typical signal intensity of fat.

5:01

The second lesion that occurs at the disco vertebral

5:04

junction is the Anderson lesion.

5:07

Easy to remember, A for all.

5:09

The entire disc over vertebral junction is involved

5:13

and what you can see is erosive abnormality with widening

5:17

of the intervertebral disc and associated bone sclerosis.

5:21

Now indeed, when you see something like this,

5:23

immediately you might think of infection,

5:25

and I've made that mistake on numerous occasion.

5:29

But you need to look elsewhere

5:30

and see the more classic features of ankylosing spondylitis.

5:36

The cause of this sort of destruction

5:39

in ankylosing spondylitis

5:41

and the other spondyloarthropathies is not

5:44

entirely agreed upon.

5:46

Some people think this relates to facet joint in, uh,

5:50

involvement with abnormal motion

5:52

at the disco vertebral junction

5:54

and multiple cartilaginous or

5:57

Nodes microtrauma may in fact be important.

6:01

Others believe that some sort of panas like material

6:05

synovial inflammatory like material

6:08

grows across the disco vertebral junction.

6:11

But in any case, this is the classic Anderson lesion.

6:14

And once again, you can study this with MR Imaging.

6:18

Here you can see bright corners of the Romans lesion.

6:22

Here's an Anderson lesion here.

6:24

It looks like an Anderson lesion

6:26

and facet joint involvement here with stir sequence.

6:31

Now the other feature of course

6:33

that occurs at the disco vertebral junction,

6:36

CDEs fight formation.

6:38

In my view, the definition

6:40

of a CDEs fight is ossification in the annulus fibrosis

6:44

of the intervertebral disc.

6:47

Classically, we're taught

6:48

that the ossification in a CDEs fight grows from the corner

6:53

of one vertebral body to the neighboring vertebral body, and

6:57

therefore, in a young person, it is a vertical thin outgrow.

7:02

But if the disease process begins in an older person

7:05

where the discs are bulge, these in deified shown here,

7:11

and here in a cadaver can look a lot like osteophytes

7:15

because their curve

7:16

or klinean appearance,

7:19

that can create some diagnostic difficulty.

7:23

Also, in the spondyloarthropathies, we get involvement

7:26

of root joints.

7:28

Now, what is a root joint?

7:29

Well, that's a name we use for a joint at the root

7:33

of the lower extremity for the hips

7:35

or the upper extremity, the glen numeral joint.

7:39

I show you this example

7:40

of sacroiliitis occurring in ankylosing spondylitis

7:44

to show you the classic features of hip involvement.

7:47

Typically bilateral symmetrical involvement

7:50

with diffuse loss of joint space.

7:53

That's very characteristic.

7:55

You may have erosive abnormalities.

7:57

You can study that particular involvement with MR imaging.

8:02

You'll see cartilage loss narrowing

8:04

of the interosseous space, joint effusions

8:08

and inflammatory reactions

8:10

and changes in the adjacent bones, both the femoral head

8:14

and acetabular.

8:16

A beautiful example of that.

8:18

And one of the features that you may see

8:20

with radiographs in particular is a collar of osteophytes.

8:25

It's not shown here,

8:26

but a collar of osteophytes

8:28

that grows across the head neck junction.

8:31

That's an important feature

8:33

because rheumatoid arthritis could also look like this.

8:36

But if you see the collar like osteophytes,

8:39

a spondyloarthropathy

8:41

and specifically ankylos spondylitis should come to mind.