0:01

So this next case is also a male

0:03

patient, a relatively young male patient.

0:05

And that's just one other point I would like

0:07

to emphasize is the average age of patients

0:10

with rectal cancer is certainly dropping, and

0:12

it's not unusual for us to see 30- and 40-year-

0:15

old patients coming in with rectal cancer.

0:17

The youngest I have seen is a

0:19

patient who is 29 years of age.

0:21

So it, and there is certainly some, um, uh,

0:25

attribution to diet and, and environmental

0:28

factors that are reducing or increasing the

0:31

prevalence in terms of age distribution.

0:34

So biopsy-proven rectal cancer, and we are being

0:38

presented with the MR to look at staging this tumor.

0:41

And so unlike the previous, uh, case where we saw it

0:44

was a T3b, this case is slightly different,

0:48

has a few additional findings that we'll be talking about.

0:52

So again, start with the sag, uh, you're

0:54

kind of getting a lay of the land.

0:55

You can see the entire rectum is laid

0:57

out nicely and is gaseous distension.

1:00

There's a small little, um, T2 bright structure

1:03

lower down in the anal canal, it could be a

1:05

thrombus internal hemorrhoid, or, you know, it

1:08

could be some kind of anal gland that's sort

1:10

of obstructed on its way to forming a fissure.

1:13

But anyway, that's sort of a benign finding.

1:15

And again, just to kind of get a sense of

1:18

the distribution of where this tumor begins.

1:21

Okay.

1:21

Uh, we are about 5.6,

1:22

and then it's sort of typically around here

1:25

is where you're starting to see the cancer.

1:28

So it's in the mid part of the rectum and

1:31

the tumor itself is about, you know, roughly

1:33

gauging is about four centimeters in length.

1:37

Now we move on to the axial and let's

1:40

see the coronal and axial side by side.

1:43

So again, that's the apple core sort of

1:45

lesion seen in the mid part of the rectum.

1:48

We measure the length, we measure

1:50

the size of the tumor itself.

1:52

And now comes the important part of staging.

1:54

So clearly when you look at this

1:57

instance, you can see the outline of the

1:59

mesorectal fascia very nicely right here.

2:01

As you can see, I'm just outlining the

2:03

outline of the mesorectal fascia on the

2:05

left hand as well as on the right side.

2:07

Here are the seminal vesicles.

2:09

Now there clearly is nodular extension

2:12

that you see going beyond the, uh, uh,

2:16

muscularis into the mesorectal fat.

2:17

So there is no doubt here that

2:19

this is a, uh, a T3 tumor.

2:22

And again, nicely laid out in this instance, you can

2:24

see posteriorly, that's the thin muscularis right here.

2:28

Compared to the prior case, there are

2:29

a couple of interesting findings here.

2:32

The first is.

2:33

Look at this structure right here.

2:36

You can see that it's a tubular structure,

2:40

which is arising from the wall and you can

2:42

actually follow a normal vessel beyond that.

2:45

So this is what EMVI looks like when there is a

2:50

signal intensity seen within the vessel, which is

2:53

expanded and the signal intensity of the abnormal

2:57

content of the vessel is the same signal intensity

3:00

as the, um, uh, as the tumor that you're seeing.

3:04

So it's this area that you see

3:06

right here, that is the EMVI.

3:08

So that in itself is a bad prognostic indicator and,

3:12

um, and, and you need to communicate that to the, there

3:16

is another area right here, which you can see nicely

3:19

that it is sort of a vessel that is emanating. And that

3:24

likely is involvement of tumor into, into the vessel.

3:28

Then the next point is, um, when you are measuring

3:31

it, clearly you measure the distance right here.

3:33

So this, you know, if we, if we draw the line and

3:37

see what the, uh, tumor extent is in terms of, it

3:40

probably is going to be more than five millimeters.

3:42

So this will be a T3C.

3:44

So it's about 7.

3:47

8 or eight millimeters extension

3:49

into the anterior part.

3:50

So that's clearly a T3, uh, Uh, C lesion.

3:55

So we know it's T3C.

3:56

We know there is EMVI or extension

3:58

of tumor into the venous plexus.

4:01

Now there are a couple of important

4:03

points about, um, T staging and what

4:06

else we need to, uh, put in the report.

4:09

So we look at the tumor extent of how much it

4:12

is extending anteriorly into the mesorectal fat.

4:16

In addition to that, we put another

4:17

measurement in our report, which is called.

4:20

as the CRM.

4:21

Now, the CRM stands for circumferential

4:22

resection margin, and that is a misnomer

4:27

because it is actually a pathologic term.

4:30

So when the surgeon eventually will operate on this

4:33

patient, the surgeon does not just take out the

4:36

rectum, they go along the plane of the mesorectal

4:39

fascia when they're doing the surgical dissection.

4:42

And this surgical margin is what the pathologists

4:46

refer to as a circumferential resection margin.

4:49

Although it implies it is circumferential,

4:51

which means it goes all along.

4:53

And that is true for the lower

4:55

and mid part of the rectum.

4:57

But once you come to the part of the rectum that

4:59

is above the level of the peritoneal reflection,

5:03

they cannot obviously resect the peritoneum.

5:04

So in that instance, the circumferential

5:06

resection margin does not encircle

5:09

or does not go the entire 360 degrees.

5:12

It sort of stops where the peritoneum inserts.

5:15

So that's one important point to keep in mind.

5:17

So in our report, we have to measure the

5:20

shortest distance from the furthest aspect

5:23

of the tumor and the mesorectal fascia.

5:26

But when you see CRM being mentioned in the

5:30

template, essentially what it is, is the

5:32

shortest distance from the furthest aspect

5:35

of the tumor to the mesorectal fascia.

5:37

You measure that distance only to the

5:39

extraperitoneal part of the mesorectal fascia.

5:43

So it seems to me that when I'm

5:45

scrolling through the axial images.

5:47

This is the point which is the shortest distance and

5:50

this is below the level of the peritoneal reflection.

5:52

And so this is what I'm going to measure.

5:55

And so again, if I measure this

5:57

distance, this distance is about 3.7 millimeters.

6:01

137 00:06:02,784 --> 00:06:07,585 And so that's what is the, um, the MRF status or the

6:07

mesorectal fascia status, which is what is equivalent

6:11

to the CRM or the shortest distance to the CRM.

6:15

Now, what is the significance of this?

6:17

It turns out that if the mesorectal

6:20

fascia is involved, which means the tumor comes

6:23

to within one millimeter or less than a millimeter

6:27

of the mesorectal fascia, then those patients

6:30

typically do worse, they have worse prognosis, and

6:33

there is a higher likelihood of local recurrence.

6:36

Whereas if it is between one to two millimeters,

6:40

then it is referred to as threatened, which

6:42

means it is coming in very close proximity.

6:44

And if it is more than two millimeters,

6:46

which is what the case is here, it is

6:48

referred to as MRF status is negative.

6:50

So in this instance, the shortest distance

6:53

that we measured is more than two millimeters.

6:56

So, this is MRF status is negative.

7:01

Now, the next question we get asked is,

7:03

when you measure the shortest distance,

7:05

do you measure it from the tumor?

7:06

What if there is a positive lymph

7:09

node or an EMVI that is in close proximity?

7:14

And the answer to that is you always

7:16

measure it from the primary tumor.

7:18

Let's say this node is positive and

7:20

we'll talk about what positivity means.

7:22

Let's assume that this node is positive.

7:24

This distance is less than here.

7:25

Okay.

7:26

You put that in your report, but keep it separate

7:29

than what the MRF status of the primary tumor is.

7:32

The reason why you do that is because you want

7:34

to tell the surgeons that when we looked at

7:36

the MR, we found either lymph nodes or EMVI

7:39

or a vessel with a tumor within it in close

7:42

proximity because that has surgical implications.

7:45

For the purposes of staging and putting in

7:47

the report, you always measure it from the

7:49

primary tumor and you do not measure it

7:52

from either a lymph node or an EMVI.

7:55

So the bottom line with this case, the two sort

7:58

of take-home messages here, is it is a disease.

8:02

When you measure the MRF, measure it from the

8:04

primary tumor and pay close attention to EMVI.

8:08

EMVI is basically tumor extension into the venous

8:11

plexus that surrounds the rectum and the way you make

8:15

the diagnosis is there is expansion of the lumen

8:18

of the vessel and that the signal intensity of the

8:21

lumen is similar to that of the adjacent tumor. So in

8:25

this case, this is a T3 disease and it is T3, which

8:29

is T3 extension, which is more than five millimeters.

8:33

So it is T3c, and there is, in addition

8:36

to that, there is EMVI, and the shortest

8:38

distance or the MRF status here is 3.

8:41

7 millimeters, so it's mid-rectal

8:43

with all the above features.

8:45

I'll be showing a couple of other examples where

8:47

we'll talk about lymph nodes, but in this instance,

8:51

suffice to say that there are no suspicious

8:53

looking lymph nodes that are T3 disease with EMVI.

8:59

And also has, so T3c with EMVI

9:03

with MRF distance being 3.7 millimeters.