0:00

This is a nine-month-old boy with

0:03

refusal to bear weight and fevers.

0:06

So this is a plain radiograph, and we

0:08

noticed immediately that as we follow

0:12

the cortical line from here to here,

0:15

you sort of lose it here, don't you?

0:17

It sort of is blurred out.

0:19

Look at the cortical line here on your fibula.

0:23

Even over here, you can still see a nice

0:25

line, a nice line on the contralateral side over

0:28

here, but here it's sort of just blurred out.

0:31

And I can't really see very much there.

0:32

I can't tell where the bone

0:35

ends and the soft tissue begins.

0:37

Let's see if that looks any

0:38

differently on the oblique view.

0:40

Yes.

0:41

Let me zoom up a little on that.

0:44

It does.

0:44

I can't see it, but again, it looks just a

0:46

little bit mottled in this area over here

0:48

and maybe a little bit in the area over here.

0:50

And on the lateral view,

0:51

can we see anything funny?

0:53

So the lateral view actually doesn't look

0:54

that bad, but what we do see is a lot

0:57

of soft tissue swelling here anteriorly.

1:00

So it really bothers me that we see something

1:02

like this on the frontal projection.

1:04

And this makes me think, especially with the

1:06

history of refusal to bear weight with fevers,

1:09

that we may be looking at a case of infection.

1:12

This is when we decided to get an MRI.

1:15

And so let me show you some MR images.

1:17

This is a sagittal, fat-suppressed,

1:19

fluid-sensitive sequence.

1:20

A lot of marrow abnormality in the

1:22

diaphysis, extending to the metaphysis.

1:25

Involving the physis, you see, you’ve lost that

1:28

trilaminar appearance, right

1:31

of your physis, and then extension

1:35

of that high signal into the epiphysis.

1:38

This is the ossified portion of the epiphysis.

1:41

But look, again, the trilaminar

1:43

appearance here has been violated and

1:45

there is extension across the epiphysis,

1:48

across the physis, into the epiphysis.

1:51

What does that look like

1:53

on post-contrast images?

1:55

So let’s bring up two at a time.

1:58

Here we’re going to have a pre-contrast,

2:01

and here we’re going to bring up a

2:03

post-contrast, just for comparison.

2:06

Again, remember, any time you get post-

2:08

contrast images, you have to compare

2:10

it with a like pre-contrast image.

2:12

Looking at the area of abnormality, we see that

2:14

there is heterogeneous enhancement, not only

2:17

in the marrow, but also some in the periosteum.

2:21

You also have abnormal signal extending across

2:23

the physis, extending into the epiphysis.

2:26

Again, disruption of that

2:29

metaphyseal enhancement.

2:30

You can see the disruption here

2:32

in the pre-contrast images also.

2:34

So there’s something wrong.

2:35

And this brings up a good point.

2:38

Anytime you think that there may be an infection

2:41

involved, or a very hypercellular process, then

2:44

it helps to get diffusion-weighted imaging.

2:47

It doesn’t look very nice, but

2:49

you’re not looking for anatomy.

2:50

You’re looking for areas

2:52

of discrete signal dropout.

2:54

And this is where I want to show

2:56

you diffusion-weighted imaging.

2:58

So here’s a diffusion-weighted image.

3:01

And we’re looking for areas of

3:02

blackness in the areas of abnormality

3:05

we detected on the other sequences.

3:07

So in this location over here.

3:09

Over here, let me bring up the sagittal

3:11

image to get a like-to-like comparison.

3:14

I’m bringing up the sagittal here, zooming in.

3:19

Notice, there’s an area of decreased

3:21

enhancement crossing the physis involving

3:24

both the metaphysis and the epiphysis.

3:26

And that area corresponds

3:28

to this blackness over here.

3:30

So that tells me there may be a

3:32

developing abscess happening in this location.

3:35

That’s where the diffusion imaging

3:37

adds value, where simple post-contrast imaging

3:39

or STIR imaging may not.

3:42

So, in the next vignette, I’m

3:44

going to show you why this happens.

3:46

Why an infection in the metaphysis

3:49

has a propensity in this age

3:50

group to go into the epiphysis.