0:00

Okay, now we've talked briefly about

0:03

the components of the epiphysis.

0:04

We talked about the articular cartilage, the

0:07

physeal cartilage, and the epiphyseal cartilage.

0:09

Now let's focus a little bit

0:10

on the physeal cartilage.

0:13

So again, we had our epiphysis, we had our

0:19

metaphysis, and we're going to concentrate

0:23

on this area right here, which is our physis.

0:27

So I'm going to get rid of this.

0:29

We're talking about just the physis now.

0:34

This is on the epiphyseal

0:36

side, and this is on the metaphyseal side.

0:42

I'm going to choose a little different color.

0:45

I'm going to make it red,

0:48

and I'm going to draw

0:52

this.

0:54

And I'm going to take yellow, and

0:56

just sort of fill in this part here,

1:02

and this part over here.

1:05

It's kind of pretty.

1:06

So, we said that this is the

1:08

metaphyseal side over here, and this

1:12

is the epiphyseal side over here.

1:14

What's drawn in yellow is going to

1:16

look like very, very bright signal

1:19

on T2 FATSAT or STIR imaging.

1:23

Uh, what's the red?

1:25

It's going to look

1:28

very dark on T2 or STIR.

1:34

Let me put that in yellow just so

1:35

you have for the sake of completion.

1:38

T2 STIR.

1:41

T2 STIR.

1:44

Right.

1:44

Bright, bright, dark.

1:46

T2 STIR.

1:46

So what are the dark areas

1:47

and what are the bright areas?

1:49

So the dark area is actually what's called

1:52

a zone of provisional calcification.

1:54

That's where cartilage, uh, is undergoing

1:57

calcification and turning into bone.

2:00

This bright area on the metaphyseal side

2:03

is what's called the spongiosa layer.

2:04

It's a very vascular area.

2:06

That's where you have a lot of capillaries that

2:09

release hematopoietic factors, humoral factors.

2:12

And because it's very vascular,

2:14

it's gonna appear bright

2:15

on STIR and T2 weighted images.

2:18

The second yellow, which is over here,

2:20

this is on the epiphyseal side, and this

2:24

is where you have these big, big cartilage

2:28

cells that are going to be undergoing

2:30

transformation and becoming bone.

2:33

Because the cartilage cells here are

2:35

so much bigger than the cartilage cells

2:37

up here, it has a lot of water in it.

2:39

And remember, we said water, that's

2:41

unbound, it's going to be bright on T2, and

2:43

that's what it's going to look like on T2.

2:46

images.

2:47

Now let's go to see what this looks like on MRI.