0:00

In the discussion of the pulse sequences that we use

0:04

for evaluation for degenerative disc disease,

0:08

I mentioned that the employment of post-gadolinium

0:11

enhanced scans is generally reserved for the distinction

0:14

between postoperative scar or granulation tissue

0:18

versus recurrent or residual disc material.

0:21

Here is a patient who has demonstrated

0:26

a large disc herniation,

0:28

which as you can see posteriorly, the patient

0:32

has already undergone laminectomy.

0:38

So here is the laminectomy defect.

0:42

Here are the normal lamina

0:46

and spinous processes.

0:48

And so, in the laminectomy bed, we see that the patient has

0:55

a non-enhancing soft tissue, which is extending from

1:00

L4-L5 downward to the L5-S1 level.

1:03

On the axial scans, we again see the laminectomy defect.

1:09

We have the thecal sac outlined and the predominant soft

1:14

tissue, which is seen anterior to the thecal sac

1:17

and compressing it, is non enhancing tissue.

1:20

This is disc material.

1:22

Now, it is not uncommon for us to see a peripheral

1:28

rim of enhancement around

1:32

the disc herniation, even in the operative bed.

1:36

And this is what some people refer to as a wrapped disc.

1:39

That is that the disc herniation has some small amount of

1:44

granulation tissue. And therefore, I use the term

1:47

predominant in the impression that the abnormality is

1:52

predominantly a non-enhancing residual recurrent

1:56

disc herniation, as opposed to granulation tissue.

2:02

Here's another patient who has been previously operated.

2:08

We see on the pre-gad T1-weighted scan to the left,

2:10

and the post-gad T1-weighted scan to the right.

2:13

And again, we have soft tissue in the lateral recess.

2:17

Lateral recess, again,

2:19

usually at the level in which we see the pedicles and we

2:21

have that nice little round curvature of the

2:23

lateral recess in the bone.

2:25

And instead, here we have this big

2:28

soft tissue lesion that is compressing the thecal sac.

2:33

In this case, as in the previous case, you'll see that there

2:36

is some element of enhancing tissue

2:41

around the non-enhancing disc fragment.

2:44

So this is, again, not unusual to have both granulation tissue and

2:49

residual recurrent disc herniation

2:51

the so-called wrapped disc.

2:54

One thing to emphasize is the importance of scanning the

2:59

patient rapidly after the administration of gadolinium.

3:03

When we initially had sort of the ionic, if you will,

3:07

gadolinium agents,

3:08

we had more time to scan the patient before the

3:13

disc itself imbibed contrast. However,

3:17

with the non-ionic and multicyclic agents,

3:24

the disc is more likely to have some of the gadolinium

3:30

agent infused into it. So scan quickly.

3:37

Another example.

3:38

So here we have a patient who

3:39

has an L4-L5 disc herniation,

3:42

and we see that the patient has been operated and

3:47

we have a laminectomy defect posteriorly.

3:52

In this case, we're concerned about this soft tissue,

3:55

which is present to the right of midline

3:57

at the level of the surgery at L4-L5.

4:03

This is the pre-gadolinium-enhanced T1-weighted scan.

4:08

We have the T2-weighted scan and then we administer

4:11

gadolinium and we see that there is predominantly

4:14

enhancing tissue here.

4:17

One thing that sometimes is a potential pitfall is the

4:24

outlining of the dorsal root ganglion or the

4:27

nerve root by the gadolinium enhancing tissue.

4:31

And the mistake for thinking that the nerve

4:37

root itself is a piece of disc.

4:41

So in this situation,

4:44

on the left side, we see the nerve root.

4:48

On the right side, we see non enhancing tissue

4:53

encased in enhancing tissue.

4:56

Is this the nerve root itself or could that be a little

5:00

piece of disc grabbing? For this,

5:01

you have to follow the sequences over the course of

5:05

multiple sections to ensure that it's moving along

5:08

the expected location of the nerve root,

5:12

as opposed to something that is there and gone,

5:16

which would be more akin to a small

5:20

piece of residual disc.

5:22

So this was granulation tissue out lining the nerve

5:26

root. So disc usually does not enhance.

5:31

If you scan rapidly immediately after the gadolium,

5:33

granulation tissue does enhance.

5:37

Here's another example which is a little bit cleaner.

5:41

T1-weighted scan to your left,

5:43

post-gad T1-weighted scan to the right.

5:47

You can see that the patient has had

5:49

a laminectomy on the left side.

5:54

And when we compare the two,

5:57

I think that it's a little less

6:00

ambiguous as to whether this

6:04

represents disc material or whether it represents a

6:09

nerve root. It's symmetric with the contralateral side.

6:12

It's in the right location.

6:14

This is going to be

6:17

the nerve root outlined by what is now

6:21

contrast enhancing soft tissue,

6:23

which previously what seen as merely non enhancing

6:27

soft tissue on the pre-gad T1-weighted scan.

6:30

So this is completely representative of granulation

6:34

tissue with no evidence of residual or recurrent disc.

6:38

It happens that that granulation tissue is encasing

6:42

the nerve root. So what do we make of that?

6:45

Well, it turns out that that's of some significance because

6:49

that granulation tissue may be causing a radiculopathy,

6:53

it may be irritating that nerve root. In such a situation

6:56

where we are concerned about arachnoidal

7:00

adhesions or granulation tissue, quite often,

7:03

the clinicians will give a temporary trial of steroids

7:09

to decrease the inflammation that may be associated with

7:12

this granulation tissue and so called put out the fire,

7:15

if you will, around that nerve root.

7:17

Because whether it's disc material or granulation tissue,

7:20

it might still cause nerve root irritation

7:23

and a radiculopathy.