0:01

The next subject I wanted to discuss is

0:03

the BI-RADS assessment categories, which

0:05

are very important in breast imaging.

0:07

These are the sort of the final

0:10

categories that are going to determine our

0:14

management for the case or the finding.

0:18

And it ranges from Category

0:20

0 through Category 6.

0:23

And Category 0 is need or needs

0:25

additional imaging evaluation.

0:28

Category 1 is negative.

0:30

Category 2 is benign.

0:33

Category 3 is probably benign.

0:36

Category 4 is suspicious.

0:38

Category 5, highly suggestive of malignancy.

0:42

And Category 6 is reserved for patients

0:44

who have a known biopsy-proven malignancy.

0:47

So that's a special category.

0:50

There's a likelihood of malignancy

0:52

that's associated with each of these

0:54

categories and that's important.

0:56

So when we give a category number, we're

0:58

also communicating the likelihood of

1:03

malignancy for that case or that finding.

1:06

So, for Category 0, really the workup isn't

1:10

finished, there's some additional imaging that

1:13

needs to be done, so we really can't assess a

1:15

likelihood of malignancy if it's Category 0.

1:18

Category one and two technically should

1:21

be a 0% chance of malignancy.

1:24

We know that there are some false-negative exams

1:27

where we call it negative, but it turns out

1:29

later that the patient has a cancer and it probably

1:32

was that finding you called negative or benign.

1:35

So let's say this is zero to 1%.

1:39

Category three, which is the probably benign

1:41

category, by definition, our likelihood of

1:45

malignancy is supposed to be less than 2%.

1:48

So that's a very small margin.

1:51

You know, basically one to

1:52

2% chance of malignancy.

1:55

And category four is a very broad category.

1:58

The chance of malignancy is anywhere

1:59

from 2 to 95%, which is very large.

2:03

For that reason, there has been some advocacy

2:06

for dividing this up into subcategories,

2:10

which is, uh, four A, B, and C with

2:13

these likelihoods of malignancy.

2:16

So 4A would be under 10%

2:18

4B would be 10 to 50% 4C

2:21

would be 50 to 95%, becoming a

2:24

little bit more granular within that

2:26

very large category. For category five,

2:30

is a greater than 95%

2:32

chance of malignancy.

2:34

And category six is 100% because

2:36

that's a patient with a known cancer.

2:39

Management differs depending

2:41

on the category as well.

2:43

So category zero usually means

2:46

something else needs to be done.

2:48

And if we're using this for MRI, which is pretty

2:50

unusual, it means that a repeat exam is needed.

2:53

And it might be that the patient wasn't

2:57

able to complete the exam or the contrast

3:00

extravasated, and that wasn't noticed,

3:03

or there was a lot of motion on the

3:06

exam and it's technically inadequate.

3:08

Something like that.

3:09

So usually category zero is for a technical

3:12

problem on MRI, where we would repeat

3:14

the full exam. For category one and two,

3:18

we're going to return to routine follow

3:20

up, whatever that is for the patient.

3:22

It might be that they go back to clinical

3:24

follow up and screening mammography.

3:26

If they're an average risk person, it

3:28

might be annual high-risk screening

3:31

MRI, if they're a higher risk person.

3:34

Category three, we usually recommend a six-month

3:37

follow-up after a category three recommendation.

3:41

BI-RADS category four and five, that's

3:42

the suspicious and sort of highly suggestive

3:45

of malignancy categories, we're going

3:47

to recommend biopsy for those patients.

3:49

And category six, that's a known

3:52

malignancy with the caveat that it's a

3:54

known malignancy and we also don't need

3:57

to do any further evaluation or biopsy.

3:59

So category six is just the malignancy

4:02

and nothing else recommended.

4:05

So for BI-RADS one and two, we're

4:07

going to do routine follow-up.

4:09

That would include clinical follow-up

4:11

for symptoms that could even be surgical

4:14

consultation for symptoms, but it just

4:16

means that we're not really seeing anything

4:18

that's explaining the problem on the MRI.

4:21

It might mean going back to screening

4:22

or diagnostic mammography, depending

4:24

on what's recommended and annual

4:26

breast MRI, depending on patient risk.

4:30

BI-RADS 3

4:31

is a little bit of a controversial area.

4:34

There has been some discussion in the literature

4:37

about this, but we don't have very clear

4:41

guidelines about when BI-RADS 3 can be used.

4:45

It has been suggested based on literature

4:47

review that BI-RADS 3 can be used on

4:49

baseline or high-risk screening exams

4:52

for a unique focus that's not T2 bright.

4:55

So T2 bright, we would call it benign.

4:57

But if it's not T2 bright and it's unique,

5:01

a mass with all the features of

5:03

fibroadenoma could be a BI-RADS 3.

5:07

I would argue that MRI is a very expensive

5:10

exam to do follow-up of a fibroadenoma

5:13

and that might be better accomplished with

5:14

ultrasound if the area is visible by ultrasound.

5:18

Also, patients who are BRCA gene mutations,

5:21

some patients will develop cancers that

5:23

have a very benign appearance to them.

5:27

So this would not include

5:30

patients who are BRCA positive.

5:33

And then focal or regional non-mass

5:35

enhancement that's not T2 hyperintense.

5:37

So T2 hyperintense, we would probably

5:39

let go as benign, but if it's not T2

5:42

hyperintense, we may be able to follow

5:44

it, especially if it's on a baseline.

5:46

And then in 2021, there's been a lot of

5:49

literature about enlarged axillary lymph nodes

5:52

related to the COVID-19 vaccine.

5:55

And we've seen a lot of this this year.

5:58

So, BI-RADS 3 is being suggested when we see

6:01

large axillary nodes in the setting of a

6:03

recent COVID-19 vaccine to that same arm.

6:08

And, you know, the recommendation usually

6:10

is that we follow up in six to eight weeks

6:12

with an axillary ultrasound, not another

6:14

MRI, with the hope that the axillary nodes

6:17

have decreased to normal size by that time.

6:20

I will say that in practice, we

6:22

also use BI-RADS 3 for some other

6:24

scenarios, even though it may not be

6:27

completely supported in the literature.

6:29

And these include probable background

6:32

enhancement, especially if it's

6:34

unusual or asymmetric patterns.

6:36

And we saw that earlier with one of

6:38

our patients that we looked at, patients

6:42

with probably evolving fat necrosis.

6:44

Sometimes this can mimic a lot of other things.

6:48

There can be some enhancement.

6:49

It can be a little uncertain that

6:51

what we're looking at is fat necrosis.

6:53

If we feel like we can make a

6:55

definite diagnosis, we will do

6:57

that and give it a BI-RADS 2.

6:59

If it's questionable, we may

7:01

recommend a follow-up.

7:02

And then the same with some types

7:05

of post-operative enhancement.

7:07

We definitely see a lot of patients who

7:08

have had an excisional biopsy or lumpectomy.

7:11

Sometimes their enhancement pattern is a little

7:14

bit unusual after those surgical changes,

7:17

and we may follow them closely for a while.

7:22

And management for BI-RADS 3 patients

7:24

includes a follow-up MRI at six

7:26

months, 12 months, and 24 months.

7:29

and then return to routine follow-up

7:31

if the finding resolves.

7:33

IREDS 4 and 5, these are patients

7:37

where we're recommending a biopsy.

7:39

So the first thing to decide when we're

7:41

reporting this is the modality for biopsy.

7:45

So does this require MRI biopsy?

7:47

Do we think we can see it on an ultrasound

7:49

and therefore do an ultrasound biopsy?

7:51

So there are some things to consider.

7:54

So for larger lesions, it may be

7:56

useful to consider a second-look

7:58

ultrasound with the intent to biopsy by

8:01

ultrasound if a lesion is discovered.

8:03

And then, if you're going to make that

8:05

recommendation, in your report, you

8:07

have to clearly indicate your plan if

8:09

the lesion is not seen by ultrasound.

8:12

Are we thinking that this might

8:13

be a BI-RADS 3 MRI with follow-up

8:16

if we don't see the lesion on MR?

8:18

On ultrasound, or are we definitely

8:21

going to need an MRI-guided biopsy?

8:24

And those are things that you don't want to

8:27

leave to your colleague to try to sort out

8:29

on the day of their second-look ultrasound,

8:31

you want to think about that beforehand.

8:33

And then for smaller things, very small

8:36

foci, small masses, non-mass enhancement,

8:40

we usually will go right to MRI biopsy.

8:43

The other thing to consider is:

8:45

Whether you need a unilateral

8:47

or bilateral biopsy.

8:50

Right now we're doing biopsies from a lateral

8:53

approach. If they're bilateral, because

8:56

we can't access the medial aspect of the

8:58

breast if both breasts are in the biopsy

9:01

coil, we would have to come from lateral.

9:04

So you have to consider some of those

9:07

logistics. Like, can you access the things

9:10

you want to biopsy from a lateral approach?

9:13

If you need a medial approach, then

9:15

maybe you'd need to do both breasts

9:18

separately or just one breast.

9:20

So we need to consider the number of biopsies

9:23

and the logistics and timing.

9:27

Often we can do bilateral biopsies all

9:29

in the same day; sometimes it takes two

9:32

appointments, so just something to keep in mind.

9:36

And then BI-RADS 6, we're going to use

9:37

this for patients with a known breast

9:39

malignancy, so that's a recent diagnosis,

9:41

not a past diagnosis, and they have no

9:45

additional findings that require a biopsy

9:47

or further workup.

9:48

So BI-RADS 6 is sort of a special category.

9:52

The standardized BI-RADS lexicon really helps us

9:55

with assessment of findings and communication.

9:58

And the BI-RADS descriptors help guide the

10:00

radiologist to the appropriate BI-RADS category.

10:04

The BI-RADS categories are associated with

10:06

management, and that's sort of definite,

10:08

this BI-RADS category equals this management.

10:12

And then the BI-RADS assessment

10:15

categories help us to clearly communicate

10:17

the next steps to both our imaging

10:19

colleagues and the referring providers.