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This first case is of a young child

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who has a frontal radiograph.

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You can see here that the patient is not

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particularly rotated.

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They're pretty well positioned,

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but we can see that the mediastinal structures are shifted

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into the right chest, that the right lung looks small

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and a little bit opa.

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Conversely, the left lung looks relatively hyper aerated

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and expanded and is causing

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that rightward mediastinal shift.

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So in this patient, there was a concern

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for an aspirated foreign body.

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I do not have decubitus views on this particular patient,

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but we can appreciate what looks like hyper

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expansion of the left lung.

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This patient went on to have a low dose CT scan,

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as I mentioned before,

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and we can see that

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as we saw on the radiographs on this low dose ct,

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that left lung looks hyper expanded

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and enlarged compared to the right lung.

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If you scroll through all the way top to bottom,

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that is consistent throughout.

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If we go to the coronal images, we can see quite nicely

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the patent distal trachea, left bronchus,

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and some sort of obstructive lesion in that left bronchus.

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So if you scroll back and forth, you'll see this persistent

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opacity in the distal left bronchus as opposed to the rest

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of the airways such as the right bronchus and its branches

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and the more proximal trachea.

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All of those look patent. In that left bronchus.

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We have some soft tissue density.

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This turned out to be aspirated chicken pieces in a young

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child who was eating chicken for dinner.

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So this is a case where the radiographs did show air

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trapping and the CT confirmed it.

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Hopefully you can see that the CT

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very nicely demonstrates not only the secondary effect

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of the air trapping, but act the actual foreign body

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in the airway as well.

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When we look at the sagittal image,

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we have further confirmation.

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There's that left bronchus in cross-section,

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and as we go peripherally, it abruptly

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stops due to the obstruction.

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This next case is to illustrate the differences of

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radiographs in inspiration versus expiration.

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This first image we see here of a child

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who takes a good deep breath in For this first image,

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we see all of our normal structures as we would expect.

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We see a normal size heart.

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We see well expanded lungs, normal mediastinal structures.

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On the other image, however, we can zoom in a little bit,

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same exact patient, same timeframe.

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However, the lungs look much smaller

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because they're in exhalation.

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We can see the mediastinal structures are kind

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of crowded with the heart.

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The heart looks a little bit bigger relative

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to the thoracic cavity,

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and that's not because anything's wrong.

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It's simply because there's less air in the air spaces

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because this patient is in exhalation.

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So it's important to remember,

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depending on the patient's phase of respiration, your chest

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Radiograph might look a little bit different

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and to not confuse a mediastinal mass, for example,

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with simply a normal mediastinum in exhalation.

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This is another patient who had radiographs.

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This patient had a clinical concern

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for an aspirated foreign body,

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and we can see on this frontal radiograph

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that the lungs look fairly symmetric.

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Perhaps there's a little bit

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of hyper expansion of the left side.

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This patient underwent decubitus views

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and it's important to get bilateral decubitus views

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in order to compare them.

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So on the next view, this says right lateral decubitus.

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That means this patient is lying on their right side

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and then we've just turned the image right side up.

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And so we have expected atelectasis of that right lung

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because it's the downside lung

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and the left lung looks hyper aerated compared to the right,

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as we would expect in a decubitus view.

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On the subsequent view,

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this is the left lateral decubitus view,

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so they're lying on their left side,

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and we would expect that

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that left side should look atelectatic just

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as the right side did on the right side decubitus view.

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However, in this patient, it still remains hyper aerated.

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If anything, it still looks bigger than the right side even

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though we're on the left side down.

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So this would be supportive

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of an aspirated foreign body into the left airway

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with resultant air trapping.

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This patient went on to have a CT scan as well,

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and we can see just like with our prior patient,

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that there is a soft tissue density lodged in the distal

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left main bronchus,

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and that turned out to be an aspirated peanut piece.

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So again, this is a patient

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for whom the radiographs were revealing

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and the CT was confirmatory.

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However, this is frequently not the case.

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These are cases where these decubitus radiographs show

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what turned out to be foreign body aspiration,

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but very frequently they're not the case.

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So the reason I'm showing these concurrently is just

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to demonstrate that because we know the radiographs are

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often not revealing, BCTs can be quite helpful

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because they will confirm whether

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or not there is a foreign body lodged into the

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airway very easily.

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This is an additional case where the opposite happened.

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This is a patient for whom an aspirated foreign body

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was concerning.

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This frontal radiograph shows fairly symmetric lung volumes

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when you compare the left and the right

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and on the cubitus views.

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We see here on the left side down to Cubitus view

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that the left lung looks smaller than the right lung,

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as we would expect due to ectasis of the downside,

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and then on the right lateral, the cubitus view,

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although the right side does look smaller than the left

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Side, the interpreting radiologist at the time

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of this radiograph was concerned

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that it wasn't atelectatic enough.

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Meaning although it does look smaller than the left side,

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it seems still a bit bigger than we would expect

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for the decubitus side.

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And so therefore, a right aspirated foreign body

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was suspected.

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This patient went on to have a confirmatory ct,

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which I'm not showing here,

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but it did not show an aspirated foreign body.

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It did not show air trapping on either side.

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So this was a false positive,

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and that's another thing to be aware of when

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considering the sensitivity of these decubitus views.

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You can also get false positives, not only false negatives.

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The final case I will show you here is an aspirated foreign

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body that is metallic.

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So it's obvious on the radiographs we can see

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that there's this unusual bar shaped metallic foreign body.

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What's important about this case though is to illustrate

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that a frontal is not sufficient to make this diagnosis

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because on a frontal, you can't actually be certain

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that this is in the airway versus the esophagus,

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like I mentioned earlier.

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Oftentimes toddlers swallow foreign bodies

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in addition to aspirating them.

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So you can't tell here where it is.

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So therefore, the lateral is an important companion image

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to have, and we can see here clearly now as we zoom in,

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that abnormal folded metallic density is in fact lodged in

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the subglottic airway

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and not in the esophagus, which would be back here.

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Similarly, if you have an esophageal foreign body,

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you can get a lateral to confirm

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that it's posterior to the airway.

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But in this case, it was in fact in the airway

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and hadn't made it all the way down into the bronchi

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because it was so large.