0:01

So we're going to move on to

0:02

some benign findings, and these

0:04

include intramammary lymph nodes.

0:07

Um, so those are circumscribed,

0:08

homogeneously enhancing masses.

0:11

They're usually reniform with a fatty

0:15

hilum, and generally less than one centimeter

0:18

in size, although they can be larger.

0:21

And we often see them in the

0:22

upper outer quadrant, but they

0:23

can be anywhere within the breast.

0:25

And frequently we'll see them going

0:27

along the lateral posterior breast.

0:30

But they can be anywhere.

0:32

And here's an example, T1-weighted

0:35

non-fat-saturated image on the left and

0:39

contrast-enhanced image on the right.

0:43

And you can see this little mass here; it has

0:46

a little bit of a fatty notch, little fatty

0:49

hilum, and that was an intramammary lymph node.

0:53

We can see a lot of non-enhancing

0:55

findings on MRI, and those are important.

0:57

To note as well,

1:01

and it frequently will notice signal

1:03

void or susceptibility artifact from

1:05

foreign bodies and clips, especially

1:08

things that are made out of metal.

1:11

They'll cause a signal void, ductal pre-

1:14

contrast high signal on T1-weighted images.

1:17

We talked about that, that that

1:18

represents proteinaceous fluid, whether

1:20

or not, you know, it can be blood.

1:22

It can just be protein-containing

1:23

fluid, but it's high signal on T1.

1:26

Cysts, postoperative fluid collections,

1:30

which can be hematomas or seromas.

1:32

And we can also see those after

1:35

needle biopsies, post-therapy skin

1:38

thickening, and trabecular thickening.

1:40

So usually related to radiation therapy.

1:43

Non-enhancing masses and architectural

1:46

distortion, especially post-surgical.

1:49

So here's an example of a biopsy clip.

1:52

The type of clip we use after a percutaneous

1:56

core biopsy, we'll place a clip, and although

1:59

the clip itself is very small, it actually makes

2:01

a fairly large signal void or signal dropout.

2:06

And that lets us know where the clip is.

2:09

So we do look for these and look to

2:11

correlate them with prior biopsies.

2:15

This is a patient who's had a lumpectomy

2:17

here on the left side, and you can see

2:20

these oval signal voids, and these were all

2:24

from surgical clips at the lumpectomy site.

2:29

This is a patient with a large known

2:34

fibroadenoma in the left breast.

2:36

Here's her mammogram,

2:38

showing her heterogeneously dense tissue

2:40

and a very large calcification here.

2:45

And then this is the corresponding

2:47

MRI showing the mass with several

2:51

irregular signal voids within it.

2:53

And this is from the course

2:55

calcifications in the mass.

2:58

This is an infusion port in the

3:03

upper inner breast or chest area.

3:06

And this one actually looks like an

3:07

infusion port, but sometimes all you

3:11

get is this, a big signal dropout.

3:14

So it depends on the amount of metal in

3:17

the infusion port, but the more metal,

3:19

the larger the susceptibility artifact.

3:21

So that one is from an infusion port as well.

3:24

So it can look like this.

3:26

Or it can look like this,

3:27

or someplace in the middle.

3:30

And then we talked about the high signal

3:33

in ducts representing proteinaceous fluid.

3:36

And here's an example, both in the axial

3:38

and sagittal plane; you can see those

3:40

ducts going up to the nipple and branching.

3:45

This is an example of a large cyst.

3:48

So that fluid-filled cyst on STIR images, and

3:52

then on post-contrast images, the background

3:54

tissue enhances, but the cyst does not.

3:59

And cysts, as I mentioned before, can have

4:01

a thin rim of enhancement around them,

4:03

and that can still be considered benign.

4:06

Often they don't have any enhancement

4:08

either within the cyst or at the edge.

4:12

This is a postoperative seroma in a

4:15

patient who had a lumpectomy for breast

4:18

cancer, and then had positive margins.

4:21

And this MRI was performed to try and

4:24

assess whether there was a particular

4:26

margin that needed to be further excised.

4:30

And in this case, you can see a fluid

4:32

collection centrally, and then a thin rim of

4:35

enhancement all the way around the seroma.

4:38

So the MRI did not show us an area that

4:43

specifically needed to be excised.

4:45

This is a patient who's had a lumpectomy on the

4:48

left side, and she's also had radiation therapy.

4:51

So you can see on T1-weighted

4:53

images, her skin is diffusely thick.

4:56

So that dark gray line all

4:58

the way around is her skin.

5:00

And it is thickened on STIR images

5:03

here on the right side of your screen.

5:04

You can see that that skin is bright.

5:08

So it is edematous; edematous thick

5:11

skin after radiation therapy, and we also

5:14

noticed that the sort of markings inside

5:16

the patient's breast, the breast tissue,

5:18

each little area is a little thicker.

5:21

And some of those areas are edematous as

5:25

well, so you often see that combination

5:28

on imaging after radiation therapy.

5:34

This is a patient who's had a lumpectomy.

5:36

Thank you. Here on the, in the left

5:39

anterior breast, you can see this

5:41

distortion and scarring here on the T1

5:46

weighted images without fat saturation.

5:48

And I love this sequence for

5:50

looking at pure anatomy, scarring

5:54

areas of postoperative change.

5:56

You see the susceptibility artifacts

5:58

really well on the T1 non-fat set.

6:01

Then we go to a post-contrast

6:03

study at the same slice demonstrating no

6:07

significant enhancement at the lumpectomy site.

6:09

And that's pretty normal for patients who

6:12

have had a remote history of lumpectomy.

6:15

It's also normal to see a little bit of

6:17

enhancement at that lumpectomy site, usually

6:19

in the first few years after surgery.

6:22

This is a patient with a mass

6:25

in the right lateral breast.

6:28

This is pre-contrast on the left

6:30

and post-contrast on the right.

6:32

And you can tell the difference because the

6:34

heart here is dark or medium signal intensity on

6:38

the pre and then it becomes bright on the post.

6:42

We also see on the post-contrast image,

6:44

the internal artery, mammary, and vein

6:46

and vessels in the breast are bright.

6:49

So no contrast enhancement at all in that mass.

6:53

The breast also contains fat-containing lesions,

6:57

and that can be helpful in interpretation.

7:00

And we often see areas of fat necrosis.

7:03

We can see hematomas, postoperative

7:05

seromas, or hematomas that contain

7:07

fat or liquefied fat, and lymph nodes.

7:11

So we'll look at a few of these.

7:13

This is a patient who had a breast

7:16

reduction and was also at high

7:20

risk, so she had a high-risk exam.

7:22

You can see this oval-shaped

7:25

area in her anterior left breast

7:28

that has intrinsic fat signal.

7:32

And this is a large area of

7:33

fat necrosis after reduction.

7:37

With contrast, we can see that there's

7:39

a signal dropout from fat centrally.

7:43

There is a little bit of

7:44

enhancement around the rim.

7:46

Fat necrosis can be very tricky because it is

7:51

common in postoperative situations and post-

7:55

traumatic situations, and it can demonstrate

7:59

enhancement either a little bit or a lot,

8:02

and it can be the reason for a biopsy.

8:08

This is a patient who had trauma to the

8:12

right breast and developed a hematoma at

8:17

the site of trauma. This is a fat-fluid

8:21

layer, with fat posteriorly and fluid

8:26

anteriorly at the site of the trauma.

8:29

And you may be wondering why the

8:31

fat is at the bottom instead of at

8:34

the top, because fat should float.

8:36

And in fact it does. You have to recall that

8:38

the patient was scanned in the prone position.

8:41

So this is actually higher than this

8:45

when the patient is being scanned,

8:47

and we just flip it for presentation.

8:50

This is an example of lymph nodes in

8:52

the axilla shown with the yellow arrows.

8:55

You can see that sort of C-shaped or reniform

8:57

shaped mass with fat centrally, and these

9:00

are normal little lymph nodes in the axilla.

9:04

This is the pectoralis minor muscle.

9:06

These are lateral to the pec minor.

9:08

That makes them level one lymph nodes.