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<v ->Okay, we're now going to move on

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to the second major category

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and that is synovial chondromatosis

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or synovial osteochondromatosis.

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Let's think of this not as a secondary problem

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as we've already talked about,

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with joint disintegration leading to intraarticular bodies,

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This is an operative picture

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that I got many many years ago.

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I cannot remember the source of this picture.

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But we're looking at an operation for this condition

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with involvement of the elbow

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and all those white areas are cartilage nodules.

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So I would remind you that in this condition

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of idiopathic synovial osteochondromatosis

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or chondromatosis,

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we're dealing first, as with a primary metaplastic process

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and second, that it may be purely cartilaginous

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or a combination of both bone and cartilage.

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So the MR imaging features will vary.

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The nodules tend to be multiple

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and distributed throughout the joint.

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And as you can see in this particular example in the elbow.

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Now, I think the MR imaging findings

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when the nodules are purely cartilaginous can be tricky.

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'Cause if you look at these cases quickly,

1:53

it looks a bit like joint fluid.

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But the joint fluid looks dirty.

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If you look at it, it's not homogeneous high signal

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but within it are areas still a little bit high

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but not so high as the fluid.

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On the T1 weighted images,

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you won't see that effect

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although there's a little bit

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of inhomogeneous signal intensity,

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but as you go to the T2

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you see areas that look more like fluid

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but areas that are gray.

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These are cartilage nodules.

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When we fat suppress the image it becomes more evident,

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maybe some areas of fluid

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but look at these cartilage nodules.

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So yes, you will make a mistake initially,

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perhaps saying you're just dealing with a joint effusion,

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but over time

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I think you'll get better and better at identifying this.

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This condition seen in young and middle aged persons.

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Once again, most common in the knee,

2:52

second place would be the hip

2:54

but this can occur in other locations as well.

2:57

And as with pigmented villonodular synovitis

3:01

in synovial chondromatosis,

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this may involve not only joints

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but bursae and tendon sheaths.

3:09

The conventional radiographic findings

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will depend upon the composition of the nodules.

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If they're purely cartilaginous

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you're probably just gonna see soft issue prominence,

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but if there's ossification

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you're gonna see areas of ossification.

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Let's look at another example here.

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Again, these are cartilaginous nodules.

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You look at them first as we look over here

3:34

on T one and fluid sensitive sequences,

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they're looking a bit, again,

3:39

like joint fluid on the fluid sensitive sequences

3:43

but there's something in it, this is dirty fluid,

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and these are the cartilage nodules.

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And you can see that nicely here

3:51

in the transverse plane as well.

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Now go ahead and give the linear.

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And what does this look like?

3:57

These look like the rice bodies

3:59

that I talked about earlier in this course.

4:02

They don't tend to enhance themselves.

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So the cartilage nodules

4:07

may in fact be of low signal non enhancing

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whereas the enhancement is mainly in the fluid

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or at the periphery of some of those cartilage nodules.

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So don't expect a lot of enhancement.

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Now, when there is osteochondromatosis,

4:26

and in fact, there is areas of cartilage and bone

4:30

that even conventional radiography

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becomes diagnostic in these patients.

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Typically, young patients have diffused ossification

4:40

about the joint on conventional radiographs

4:43

in homogeneous signal intensity

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when you study this phase of the disease by MRI.

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And I can tell you the cases of synovial osteochondromatosis

4:54

make for some of the prettiest images you will ever see.

4:58

For example, involvement of the glenohumeral joint

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mainly with ossified bodies

5:03

scattered throughout most of the joint.

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Remember when we talked about

5:08

bodies derived from the joint surface

5:10

that is secondary synovial osteochondromatosis,

5:14

I made the point of some of the differential features.

5:18

With a secondary variety, fewer bodies,

5:22

bodies of not equal size, all right?

5:24

They vary in size, not distributed throughout the joint.

5:29

With the idiopathic variety,

5:31

many more bodies, more equal in size

5:35

and generally distributed over large segments of the joint.

5:39

Here at the glenohumeral joint, here are beautiful case

5:43

involving mainly the anterior aspect of the ankle joint,

5:47

pretty images as you would expect.

5:50

And here with CT,

5:52

these are some of my most beautiful images.

5:55

And so many bodies here

5:57

distributed throughout the elbow joint.