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In this lesson, we're gonna talk about,

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uh, mammographic asymmetries and

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masses, their imaging characteristics.

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As you might remember, uh, BI-RADS

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provides some definitions of

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asymmetries that are slightly different.

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An asymmetry by itself is an area of fibroglandular

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density that is visible on a single mammographic

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projection—CC, MLO, something like that.

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It's typically superimposed fibroglandular tissue

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that needs to be worked up a little bit further.

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A focal asymmetry, in contrast, is a relatively

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small amount of fibroglandular density

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tissue over a confined portion of the breast.

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It has similar shape on different

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mammographic projections,

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convex outward borders, and

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usually with interspersed fat.

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And this we see on two views, right?

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So asymmetry and focal asymmetry are very

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closely related, um, but differ based

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on how many views you see them on.

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A developing asymmetry,

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although similar in name to our standard asymmetry,

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is actually more like a focal asymmetry, um,

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because it's a focal asymmetry that is new, larger,

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or more conspicuous than that on prior exams.

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So by definition, developing asymmetry

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can only be identified in patients who

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have prior imaging exams to compare to.

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So basically, a developing asymmetry is a focal asymmetry

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that is increasing or changing in some way.

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In table format, we can see some differences.

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Uh, between—here again, I've noted that the

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main difference between asymmetry and focal

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asymmetry is how many views you see it in.

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Asymmetries tend to have—at least when

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a lot of this research was done—uh,

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have a very low risk of malignancy.

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If it is malignancy, it's more likely A-L-C or I-L-C.

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Focal asymmetries have a 0.5 to 1% likelihood

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of malignancy without other features.

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This can be—just so we're aware—a reasonable

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BI-RADS reinterpretation. That would be a focal

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asymmetry without an ultrasound correlate.

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A global asymmetry, which I didn't mention before,

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um, is relatively rarely used in clinical

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practice, but it's a large amount—greater than

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one quadrant—of fibroglandular density tissue.

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Usually, it's just a normal variant or variant

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fibroglandular tissue in the breast.

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Usually not anything to worry about, and

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I would say most people probably just

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interpret this as negative or benign.

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Again, developing asymmetries—

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focal asymmetry that is new.

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The important thing about this is

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that the developing asymmetries,

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a pretty good chunk of them are

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found out to be malignant—about 15%—

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and certainly warrant further workup.

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This case is demonstrating a focal asymmetry.

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We see this area of fibroglandular density tissue.

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We see it in two views.

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It's in the lateral and upper part of the

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right breast, probably about 10 o'clock.

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Now, of course, this one I think would really

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border on the idea of a global asymmetry, right?

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It's almost full quadrant.

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Um, you could make the argument this is

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either a very large focal asymmetry or a

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global asymmetry.

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Um, but it demonstrates some of the important features

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of focal asymmetry, meaning that there's some concave

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margins, there's some interspersed fat, kind of

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looks like what we would just call normal tissue.

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Now, of course, if this is small and focal,

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um, stands out from the rest of the glandular

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tissue, then we'd wanna work it up further.

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In this case here, I'm demonstrating a developing

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asymmetry in the superior part of the left breast.

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On this MLO view, we see the small asymmetry here.

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Now, I'm not showing you the CC

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views, but they were similar.

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Um, that's why we saw it on the CC views.

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And so we can call it a focal asymmetry.

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And if we look at this exam, this is, let's say, um,

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an exam from several years ago.

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This is maybe one, two years ago,

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and this is our current exam.

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We see that this focal asymmetry

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is getting larger in size.

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This was subsequently biopsy-proven ductal carcinoma.

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Now we know that we have the overall

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decreased recall rate for tomosynthesis.

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Um, and this is particularly true for asymmetries.

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DBT has an increased ability to decipher

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normal superimposed dense tissue from a true

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lesion, um, leading to a lower recall rate for

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asymmetries on tomosynthesis screening exams.

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True lesions are ones that persist.

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Uh, even on DBT, should be further

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evaluated with diagnostic mammogram.

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Possible ultrasound—we can do spot compression

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tomosynthesis that can help assess

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the possibility of tissue superimposition.

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You can also do rotated spot compression views,

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um, which can sometimes help sort of really

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get a good view of that superimposed tissue.

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Sort of separate the tissues even a little further.

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Um, one-view asymmetries can be better

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localized for additional mammographic

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views. With DBT, of course, we can use that

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sort of imaging stack scroll bar to help us.

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It has some challenges, as we mentioned

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in previous lessons, um, but you can use

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it to help you identify a particular area.

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For masses,

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uh, BI-RADS defines a mass as a three-

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dimensional object that occupies space,

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completely or partially convex outward borders.

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In distinction with focal asymmetry, it's denser at

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the center than the periphery, and like a focal asymmetry,

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it's seen on two different mammographic projections.

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We wanna describe a few things when we see a

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mass—that includes the shape, margin, and density.

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And here we show a good example

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of a classic sort of mass, right?

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In this right breast,

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we have a CC and MLO view.

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We see this very large, uh, oval mass.

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It has some circumscribed margins,

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maybe a few indistinct margins.

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Um, and one of the associated findings

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in this mass are these prominent, uh,

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fine pleomorphic calcifications. Of course,

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when we see those associated with a mass,

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this raises our suspicion for malignancy

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quite a bit. And we can see that this

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mass is already biopsied previously, and

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we can see the biopsy marker clip here.

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Again, a smaller demonstration of a mass.

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Here we're showing left CC and

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left MLO views in the lateral,

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lower aspect of the left breast.

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So this would be approximately maybe four

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o'clock on the left—something like that.

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Um, we see this irregular mass.

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It's got spiculated margins, and it's

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high density compared to the rest of

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the fibroglandular tissue.

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Now, of course, this is sort of your

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classic malignancy, right?

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Um, got those spiculated margins.

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Um, and this was biopsied—Invasive Ductal Carcinoma.

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Um, masses are particularly

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well visualized on DBT.

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Um, we can remove the layer of

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those superimposed dense tissue.

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Um, we can see the margins a little bit better.

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Um, this can help us in the setting

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of multiple bilateral masses

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to put that into the benign category.

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We can also have improved detection

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of small spiculated masses.

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We can see those margins better.

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It's not hidden amongst that dense tissue,

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which helps improve our ability to

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identify those really tiny cancers

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that are more likely gonna be node-negative.

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Um, we get better margin analysis, and may

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improve localization for subsequent ultrasound exams.