0:01

Let's summarize the findings of the two cases of diskitis and osteomyelitis

0:06

that we just saw. In diskitis and osteomyelitis, we see disk and endplates

0:11

brighter on T2 weighted scan, dark on T1 weighted scan, and they may

0:15

show contrast enhancement. Erosion of the endplates will help you in distinguishing

0:20

degenerative Modic Type 1 changes from infectious inflammatory changes.

0:28

If you have a paravertebral mass, that's not going to occur in the

0:32

degenerative changes. And if it's in the soleus musculature, you may suggest

0:37

that it represents a TB abscess in the soleus. Beware dialysis arthropathy.

0:44

This also can be dark on T1, bright on T2 with endplate erosion,

0:49

sort of like the amyloid deposition disease in the endplates that can simulate

0:55

diskitis and osteomyelitis. Here's an example in the thoracic spine. We

1:01

saw a couple lumbar spine cases, here you have bright signal intensity extending

1:06

from the vertebral body into the disk. There's an epidural component that's

1:10

compressing the spinal cord with abnormal signal in the spinal cord on the

1:14

T1 weighted scan, darkened signal intensity on the post gad scan.

1:20

We see the enhancement in the disk, which should not be there,

1:22

as well as the enhancing inflammatory disease in the epidural space.

1:28

Remember that the adjacent spaces of the retropharyngeal space and prevertebral

1:34

space may show bright signal intensity on T2 weighted scan. If we're in

1:38

front of the longus musculature, we're in the retropharyngeal space. If

1:43

we're behind the longus musculature, we're in the prevertebral space.

1:50

Here we have a post gadolinium and a T2 weighted scan. We notice that

1:55

there is extensive inflammation that is present in the anterior epidural

2:00

space behind the vertebral bodies, but we're also seeing bright signal intensity,

2:05

which is posterior to the longus musculature, in this case, in the prevertebral

2:10

space. That's not as important, clearly, as what's happening more posteriorly,

2:16

and with the compression of the spinal cord by this inflammatory mass.

2:22

Here's another example. This patient had a posterior epidural space abscess.

2:29

This is the non enhancing component of the purulent material, suppurative

2:34

material abscess in the posterior epidural space. Notice that the disks

2:40

and the vertebral body are not showing enhancement and they're not bright

2:43

in signal intensity on the STIR image. In this case, the posterior epidural

2:49

abscess was from a genitourinary tract primary infection, with haematogenous

2:56

spread to the posterior epidural space. Having an epidural abscess in association

3:03

with a genitourinary tract infection, be it of the kidneys or in the

3:08

bladder, is not that unusual and should be sought after if you don't

3:13

see infection primarily from the vertebral column. Let me just go back and

3:19

note that these areas here which are bright on T1 post contrast and

3:24

bright on the T2 weighted scan, represent Hemangioma of bone and are not

3:29

related to the infection. How do we distinguish between a phlegmon versus

3:34

an abscess? This is the question that we've been asking when we talked

3:37

about tonsillitis and peritonsillar abscess. When we talked about retropharyngeal

3:43

space with phlegmon versus abscess, you wanna try to see a rim of

3:47

gadolinium enhancement and fluid signal intensity and an abscess, as opposed

3:52

to, sort of, a more diffused gadolinium enhancement

3:57

with a phlegmon without a central absence of enhancement.

4:02

Both of these will be seen in association with the diskitis osteomyelitis

4:06

with bright signal in the endplates on T2 weighted scan, and enhancement

4:10

of the endplates that occurs in about 97% of patients with diskitis and

4:14

osteomyelitis. One thing that is unique about tuberculosis is, sometimes

4:18

you will see that the inflammatory tissue is actually not all that bright

4:22

on T2 weighted scan. It can be intermediate in signal intensity and that's

4:27

thought to be part of that granulomatous collection that occurs in this

4:32

type of infection. Here is another example of a patient who has a

4:39

rim enhancing collection in the posterior epidural space, and this is located

4:45

at the C7 T1 T2 level. Here you have it on the T2 weighted scan

4:50

with an associated normal signal intensity to the spinal cord.

4:55

The spinal cord may be bright in signal intensity on these type of

4:58

examinations, not just because of compression by the collection, but it

5:03

may be bright in signal intensity because of associated thrombophlebitis

5:08

and venous ischemia that can injure the spinal cord. Here on the

5:13

gradient echo scan and the post gadolinium enhanced scan, we find an interesting

5:18

observation. This collection is in the subdural space.

5:24

Notice that the edge of the dura here

5:28

is actually continuous posteriorly rather than anteriorly. This is because

5:35

this is a collection in the subdural space rather than in the epidural

5:39

space, where that low signal intensity would be displaced anteriorly. So

5:45

this is an a subdural empyema in a patient who had

5:51

fever and neck pain.