0:00

Here we get into some more severe cases of

0:03

where these patients tend

0:05

to lose their vascularity over time.

0:07

And this is a beautiful case of gangrene

0:10

and sometimes this is when I'll actually open up the patient

0:14

chart or the, the electronic medical record to look for

0:19

like physical pictures of the foot to match up

0:23

with our radiographic abnormalities.

0:26

Radiographically, you can appreciate the soft tissue

0:28

wasting, particularly involving the second toe.

0:32

And on MRI, we can see the T one hypo

0:37

hyperintensity here in the middle phalanx,

0:40

but hypo intensity in the distal phalanx of node.

0:44

In the setting of this gangrene where there's a lot

0:47

of soft tissue loss, you'll oftentimes lose

0:50

that signal intensity entirely on the stir sequences.

0:54

And here on the sagal images

0:55

where you just have see this abrupt cutoff of the toe,

0:59

which seems to come back with our T one weighted sequences.

1:01

But as we turn our attention to the um, uh,

1:05

axial images here, we can see

1:07

that there is low signal intensity throughout the entirety

1:10

of that second toe on both the stir

1:12

and also T one weighted sequences.

1:14

And this is actually representing soft tissue air within

1:18

that gangrenous toe.

1:21

And you may, um, uh, just presume

1:23

that there is underlying osteomyelitis in, in this toe.

1:27

Even if we gave intravenous contrast,

1:29

then there was no enhancement.

1:31

That toe is likely, uh, infected.

1:34

Here's another case

1:35

of gangrene this time involving septic arthritis

1:38

of the interphalangeal joint.

1:40

We see all the heart marks with soft tissue ulceration,

1:43

peripheral rim enhancement of this, um, this joint effusion

1:47

that's at the interphalangeal joint.

1:49

This is an interesting, uh, phenomenon called the ghost sign

1:52

where we have obliteration

1:55

of the bony structures on the T one

1:58

and uh, the T two weighted sequences.

2:01

But on post contrast sequences, the um, bone detail tends

2:05

to come back a little bit

2:08

and this is, uh, called the go sign.

2:10

And this is when there is associated osteomyelitis in the

2:15

background of all this osseous destruction.

2:18

But the vascular supply is still relatively maintained.

2:21

Thus, the detail coming back on the post contrast sequences.

2:28

Here's another case of, uh, severe gangrene This time

2:33

I think it's pretty obvious radiographically there is a lot

2:36

of air within that great toe,

2:38

but this is the importance of giving that contrast

2:41

and to see these areas of non enhancement such that we know

2:45

that these areas would not be treated if we put the patient

2:50

on some IV antibiotics.

2:52

Not only do we see these areas of sharply demarcated, um,

2:56

non enhancement, but we see the interros abscesses

3:00

that are located within the base of the fifth metatarsal,

3:03

sorry, the first metatarsal as well.

3:07

And I know none of you're going to believe this

3:09

or me that this is actually a 68-year-old man

3:14

with a case of frostbite in San Diego.

3:17

But I tell you, no lies here.

3:20

This is how it was presented to me.

3:22

So this is an example of a case who had a frostbite,

3:27

but he came to us because he had just black toes

3:31

and they were worried about osteomyelitis.

3:33

We went ahead and did his MRI

3:36

and see this tremendous amount of edema along the dorsum

3:41

of the foot and throughout the musculature of his forefoot.

3:45

But after we gave him the intravenous contrast,

3:47

we see these patchy areas of non enhancement.

3:50

And even when we look back to it,

3:51

we can see there is actually foci

3:53

of low signal intensity along the plantar surface

3:56

of the foot, which represented areas of air, uh,

4:00

within the soft tissues, the dead soft tissues as well.

4:04

So again, this is important to know what is the,

4:07

where the revitalized tissue is

4:09

and where the vital tissue is such that the, um,

4:12

surgeon can know where to actually make their cut.

4:19

And lastly, of the necrotizing infections,

4:22

this is a beautiful case with trim, a lot

4:25

of air within the plantar soft tissues, um,

4:28

and extending in

4:30

and through the first metatarsal phalangeal joint into this

4:34

little soft tissue air pocket.

4:36

And this, uh, this another sinus tract that's entering

4:40

through the dorsal surface of the uh, foot.

4:43

Many times these necrotizing infections are gonna be multi

4:47

microbial, so it's when you actually tie

4:50

to take a sample out of it

4:52

and you'll have multiple things in this case,

4:55

all these things I cannot pronounce.

4:58

So just remember, uh, that, uh, that's going to be the case.

5:03

So moving to some of these patients who have then tried

5:07

to have some sort of intervention, we have a very active,

5:11

um, active angioplasty surface

5:15

and some of these patients, uh, are able to be recanalize

5:18

and angioplasty such that their

5:22

vascularity is actually preserved.

5:24

However, one of the things

5:26

that we can see subsequently post angioplasty is the bone

5:30

infarction due to relative hypovascular, um,

5:34

dur prior to the revascularizations um, process.

5:39

And the T one weighted sequences show that classic

5:43

double line sign, um, on the T two weighted sequence

5:47

and altered marrow signal intensity on

5:49

the T two weighted sequence.

5:50

Here we can see kind of relative revitalization of the, uh,

5:54

soft tissue portions of this

5:56

Toe as well.

5:58

And in the more proximal areas,

6:01

you may appreciate these serpentine areas

6:04

of signal alteration throughout nearly every

6:08

bone in the foot.

6:09

And this is all avascular necrosis in the setting

6:13

of a prior, uh, revascularization surgery.