Interactive Transcript
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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.
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