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The next congenital lung malformation we will discuss is

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bronchopulmonary sequestration.

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These are made of dysplastic lung tissue, again, probably

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with some sort of early airway obstruction in embryogenesis

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and also potentially an accessory lung bud.

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Unlike the C pans that we discussed in the last section,

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these do not communicate with the airway.

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Importantly, these have systemic arterial supply

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and so this is an important finding that we look

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for on imaging, whether prenatal

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or postnatal like CPAM on postnatal imaging,

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we can sometimes see adjacent hyper lucid lung

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and these also like CPAM can regress prior to birth.

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There are two main flavors

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of bronchopulmonary sequestration, the intra lobar type,

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which makes up the majority and the extra lobar type.

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The intra lobar type do not have a separate pleura from the

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adjacent lung, and their mean drainage is usually

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through the pulmonary venous system,

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whereas the extra lobar type does have its own separate

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pleura and its venous drainage system is

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through the systemic venous drainage system.

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The intra lobar type may contain air even though it does not

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communicate with the tracheal bronchial tree due

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to collateral drift

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as it doesn't have separate pleura from the adjacent lung,

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but it can also contain fluid

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or a combination with air fluid levels or consolidation.

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On the other hand, extra low bar typically looks cystic

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or even solid or soft tissue density.

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The intra lobar type is more commonly diagnosed in childhood

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or a little later in life due to recurrent infection

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of the sequestration itself,

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whereas the extra lobar type more commonly is diagnosed

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prenatally or perinatally.

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The extra lobar type

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because it's separated by its own flora,

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can also be sub dive pragmatic in location

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and can sometimes, rarely also tos thrombose or hemorrhage.

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The first case I'll show you, we'll start with a fetal MRI.

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We can see axial and coronal T two images.

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We'll start with the axial images

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and you can see here as we scroll up

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and down, we see the normal dark part here

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and then we see that there's a distinctive separation

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between the posterior left lung

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and anterior left lung

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where the posterior portion looks much brighter.

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It also looks brighter than the contralateral right lung,

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and so as we scroll up through the chest

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we can really see how there's that clear demarcation.

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Additionally, you can see a

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prominent flow void in the medial portion of this,

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this lesion that seems to be connecting

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with the aorta right here.

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This is a typical look for a bronchopulmonary sequestration

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with systemic arterial supply directly off the aorta.

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The systemic arterial supply does not need

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to be the aorta necessarily.

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It could be from a branch, but in this case we see it

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coming off the aorta.

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To confirm on coronal images, I'm gonna zoom in here

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to the chest again, we see very clear demarcation

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of the hyperintense lesion on the left side with

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systemic arterial supply branching off

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of the descending aorta.

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This patient had their postnatal CTA

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and we can see when we focus on the axial

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soft tissue images that arising off of the descending aorta

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is a branch going towards the left lower lobe.

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And as we scroll, we see that branch going into this region

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of soft tissue density.

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When we look at the same area on the lung windows on axial

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lung windows, again, we see that large

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vessel coming off the aorta into a small area

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of soft tissue density or consolidation,

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and we can see a little bit of adjacent hyper aerated lung.

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So this was a bronchopulmonary sequestration

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with the large feeding artery that we saw,

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but the lesion has substantially decreased relative

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to the rest of the baby's size compared to the MRI

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and to confirm again on the coronal, we can see

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that artery coming directly off

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of the descending aorta going into the lesion

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and adjacent hyper lucent lung.

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Same thing on the sagittals. Here's our lesion.

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Here's some large arteries and other vessels in the lesion

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and the adjacent hyper aerated lung.

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So although we still have the lesion here,

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it's substantially smaller than it was when we

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saw it on the fetal MRI.

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The next patient also has a fetal MRI.

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We're focusing here on the coronal T two images,

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really similar appearance.

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We have a clear demarcation of hyperintense

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lung tissue on the left side

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and we can see a large systemic feeding artery coming off

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of the descending aorta and branching into the lesion.

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We can scroll back and forth a little bit

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to convince ourselves that that's what's going on.

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Very similar appearance to the last case.

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This patient went on to have their postnatal imaging

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and again, focusing on the axial images.

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First we can see that here's the descending aorta.

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We're gonna ignore the right side

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of the patient for the moment.

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We're gonna see that there is a feeding artery coming off

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of the aorta, going towards some soft tissue density in the

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posterior left lower chest.

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So that aortic branch is feeding this structure here.

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If we change to our lung windows, we again see a little bit

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of hyper variation nearby.

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Going back to our soft tissue windows, interestingly

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separately, we have an additional enhancing lesion

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that we did not see on the fetal MRI on the right side.

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This actually turned out to be an infantile heman,

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which is an interesting incidental additional lesion.

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Looking at the corresponding coronal images, we can see

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the sequestration has a bit of a triangular appearance here.

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We can see some hyper aeration of the adjacent lung

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and again, we see the feeding artery coming directly off

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of the aorta to the lesion.

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Probably a couple of branches there

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and again, we see that incidental infantile hemangioma.

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The next case we see a fetal MRI

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with axial cron and sagittal images will start

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with the axial images.

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Very similar picture.

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We see this left posterior lung

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hyperintense region.

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Again, this baby is moving, so uh, we have a little bit

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of motion artifact there,

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but we can see this hyperintense portion

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that looks distinct from the anterior part of the left lung

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as well as the right lung.

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It is harder to appreciate a distinct feeding artery

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arising off the aorta.

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In this particular case.

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Looking at the coronal images, we see something similar.

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We see this hyperintense lesion

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that looks different from the other side and

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although there's some flow voids centrally,

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we don't see it clearly connecting with the aorta.

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And then again, on the sagittal, a little bit easier

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to appreciate that clear demarcation

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between the hyperintense abnormal lesion.

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And then the rest of the lung.

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This patient went on to have their postnatal CTA,

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and we can see that in this patient.

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The lesion has also decreased in size.

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We see some soft tissue density in that area.

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We don't clearly see a branch coming off of

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that aorta going to this lesion,

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which has decreased in size.

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So why am I showing you this case when I've just said

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that bronchopulmonary sequestration need to have

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feeding arteries?

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Well, it turns out that pathology,

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this particular lesion was what's called a hybrid lesion.

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It had features of both bronch pulmonary sequestration, but

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Also CPAM, congenital pulmonary airway malformation

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that we discussed in the last section.

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And that is not altogether uncommon.

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Again, because these congenital lesions are thought

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to have a common origin,

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sometimes we can see features of both.

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We would expect to normally see some sort of feeding artery,

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and we do not in this case.

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Uh, it doesn't mean it's not there.

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It might just be too small for us to see on the ct.

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So on the prenatal MRI,

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the leading differential diagnosis was A-C-P-A-M.

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And on the CTA, it was still thought

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to be A-C-P-A-M since we did not see an obvious

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feeding artery.

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But at pathology it turned out to be a hybrid lesion.

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The reason I mentioned this is just to know

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that there is a lot of overlap between these lesions.

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In the earlier section, when I discussed CPAM,

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I showed mostly cases with discreet cysts,

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but it's important to know that you can also have CPAM

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that looks very similar to sequestration,

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where you just have a hyper lucid lung due to microcysts.

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And so I wanna make it clear that there can be a lot

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of overlap

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and it can be very difficult to distinguish these lesions.

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So just because you don't see the artery doesn't mean it's,

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there isn't some sort of sequestration component.

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If you do see the artery,

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then there is a sequestration component,

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but just know in real life it's not quite as clear cut.

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It can be a little bit confusing sometimes, and that's okay.