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An important question is

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how do we tell airway secretions from airway true nodules

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that need to be followed and managed?

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Here's an example in the small airway,

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and we're gonna look very careful at its density

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and we can measure its ville units.

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This is the lung windows.

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We can see the smoothly marginated nodule in the proximal

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right main bronchus right here at the level of the Karina.

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When we look at it on the soft tissue windows, we can see

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that it is visually lower density

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than the other soft tissue structures such as the aorta

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and pulmonary artery.

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So it's low density, it's mural adherence,

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it has obtuse angles with the wall, not acute angles.

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And these are all features of endobronchial secretions.

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You can measure hounds field unit density in something like

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this, and it did measure under 21 hounsfield units low

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density consistent with fluid like secretions.

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So this would be considered a lung rads.

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Two, there's no reason to call this patient back

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for interval imaging

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and we'll just check on it the next time the patient comes

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back for their annual screening exam.

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So endobronchial secretion in the central airway,

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the same patient, not surprisingly, had multiple areas

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of subsegmental moid impaction throughout the lungs.

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And here's just one picture from their right upper lobe

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and a picture from the lingula showing

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multiple tubular filling defects.

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This one's got a little bubble of air.

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There's filling defect here with a little mural thickening

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and a filling defect here with a little bubble of air in it.

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So this is a patient who most likely has chronic bronchitis

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where production of secretions is very common

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and usually first thing in the morning when they wake up

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from sleep, they have a kind of a copious amount

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of secretions that they're clearing.

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So if we get to that, how can you prevent having these on

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your CT To begin with?

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Having a patient coming for lung screening,

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take several deep coughs

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before they lay down, can help clear some

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of these secretions out of the airway,

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and then you won't even see them on your exam.

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And then sometimes we're left

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with the isolated subsegmental nodule.

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This patient has tiny little bits of emphysema

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and if we look through the rest of the exams,

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you could see there was multiple areas of mild emphysema

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and we know they have some form

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of chronic obstructive pulmonary disease.

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This patient has a tiny linear area of secretion here.

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This just a linear filling defect, very small, hard to see

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and may not even be detected.

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And then we have really one solid endobronchial

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filling defect in this patient.

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Here's that little tiny linear secretion, okay,

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that we can call secretions.

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We're good, but then we have this smoothly marginated

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endobronchial nodule

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because it is distal to the segmental airways.

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We consider these airway secretions.

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We consider this a lung rads two,

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and the patient would come back

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for their next annual screening in 12 months.

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The ones that we get concerned about are whether

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they are segmental

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Low bar or in the main to tracheal bronchi.

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So the central portion of the tracheal bronchial tree

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trachea down to segmental airways.

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We consistently can evaluate them on ct

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and then when they get to the subs segmental level,

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we consider these negative screens most

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consistent with secretions.

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So that's a look at nodules

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that occur in the airways from the ones we

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need to be concerned about.

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Solid nodules in the trachea

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through segmental bronchi give us the most concern

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and patients should come back as a lung rides four A

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with an interval CT in three months,

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or airway nodules that are low density, linear, frothy,

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contain air bubbles.

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We consider those negative screens outright.

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We make them a category zero in terms of any reporting.

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In other words, you don't need to report them

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with a lung ran category.

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And then we have some of these nodules that are in between

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where if they're subsegmental

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and smaller, we consider them secretions.

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Even if you can't see the frothy air

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or the low density within them because they're quite small.