0:01

This is a patient who is being evaluated for post-op

0:04

lumbar spine surgery for degenerative disease.

0:08

The patient was known to have compression deformities of the

0:11

vertebral bodies and so this was also performed as

0:13

a follow up for those compression deformities.

0:16

If we look on the T1-weighted scan,

0:18

we see multiple vertebral bodies that are wedge-shaped.

0:22

However, the signal intensity of the vertebral body on T1

0:25

weighted scan, even in the compressed vertebra,

0:28

shows normal bone marrow signal.

0:30

This is typical of osteoporotic compression fractures where

0:35

after the course of time after the acute compression,

0:38

the signal intensity of the vertebral body returns

0:41

to normal bright on T1-weighted scan.

0:44

However, you also note that there is a cystic lesion which is seen in

0:48

the epidural fat at the thoracic region, at the site of

0:53

where there has been this compression fracture.

0:56

This cystic lesion shows very bright signal intensity

1:00

on the T2-weighted scan. This border of darker signal

1:05

intensity is likely a chemical shift artifact.

1:09

However, it could represent the dura itself.

1:12

So as you follow the dura lining posteriorly, you see that it may

1:17

actually be displaced anteriorly by the cyst at that junction.

1:22

On post-gadolinium enhanced scans,

1:25

there was absolutely no enhancement associated with the

1:28

cyst. When we look further inferiorly at the operative bed,

1:32

you can see that there has been extensive instrumentation.

1:36

There also has been vertebroplasty of compressed

1:40

vertebrae, which is seen here as the darker signal intensity

1:45

amidst the bone marrow, and an absence of other enhancing

1:49

lesions. So when we have this cyst that is

1:53

in the epidural space, showing signal intensity

1:57

characteristics of CSF, without enhancement,

2:00

in a patient who has been instrumented both

2:03

for surgery, as well as for vertebroplasty,

2:06

we would suggest that this is most likely

2:08

an epidermoid cyst which is acquired.

2:12

We would confirm this diagnosis with a diffusion-weighted scan.

2:17

On the diffusion-weighted scan,

2:19

we would expect this to be bright rather

2:22

than dark in signal intensity.

2:24

The diffusion-weighted scan for a benign CSF-containing cyst

2:28

is dark on DWI, whereas an epidermoid is bright on DWI.

2:34

When we do the ADC maps,

2:35

we would expect it to be dark in signal intensity suggesting

2:40

restricted diffusion in an epidermoid cyst.

2:43

Unfortunately, that was not performed in this patient.

2:47

However, it was confirmed at surgery.