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Let's take a look at the lungs in this patient who's come

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for their lung cancer screening CT exam.

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We know that certain findings, like evidence of COPD

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and emphysema are common

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and interstitial lung findings may also be present related

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to cigarette smoking or other conditions

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and provide us an opportunity for early diagnosis,

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treatment and intervention.

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As we start to look at the lung apices,

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we can already see numerous small areas

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of low density parenchyma.

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Some are small and scattered with normal intervening lung

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and others are becoming more cofluent.

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This is relatively mild emphysema.

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As we scroll down the lungs, we start to see less

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and less emphysema, which is very characteristic

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of smoking related lung disease.

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If we think about the ventilation

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and perfusion of the lungs,

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it makes great sense why most smoking related conditions are

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upper low predominant cigarette smoke.

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Inhalation of particles

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that sit within the small airways is less likely

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to clear quickly from the upper lobes

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because there's less ventilation.

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There's also less perfusion

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to the upper lobes and the lower lobes.

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So bringing in things like macrophages in the circulating

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blood that can help clear abnormalities in the lung

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is less common.

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So less ventilation

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and less perfusion in the upper lobes compared

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to the lower lobes contributes to the increase

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of abnormalities associated with cigarette smoking

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in the upper lobes.

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That includes emphysema,

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upper lobe predominant central ular emphysema

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as the characteristic emphysema in individuals who smoke

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lung cancer is twice as more likely

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to occur in the upper lobes than the lower lobes.

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Something that we're looking

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for on lung cancer screening cts.

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So in addition to the emphysema in the lungs here,

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which is relatively mild

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and overall extent, um, we're gonna look for other evidence

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of COPD.

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So we're gonna look at the small airways here.

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They look nice and thin

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with well-preserved airway channels down

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here in the lower lobes.

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Nice airway lumen with nice thin airway walls with no focal

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or nodular thickening and no areas of mucus plugging.

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But it's important for us to sample the lungs, look

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through the airways to look for these features

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of airway wall thickening.

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We do have some mucus plugging if we follow this bronchus

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right here in the right upper lobe.

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This one's an anterior segmental bronchus.

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We have the posterior segmental bronchus here

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and as we follow it out we see a filling defect within it.

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And these filling defects represent mucus plugging.

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Mucus plugging is increasingly recognized to be associated

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with exacerbations of COPD and increased morbidity.

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Here's another bronchus anteriorly in the left upper lobe

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and we can see areas of excentric material

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lumpy abnormality within what is an

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Otherwise normal airway with a thin wall.

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So we have multiple foci of cleide impaction.

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So we look for airway wall thickening

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and we look for things inside the airway lumen

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that represent cleide impaction.

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Both important to report as findings

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of obstructive pulmonary disease

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that are potentially treatable

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to manage the patient's underlying pulmonary function

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and preserve lung tissue.

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One other way that we can look at the lung parenchyma

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quantitatively is we can measure the amount of emphysema.

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This is a tool that we use in our practice,

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which simply applies uh, attenuation threshold

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of minus 950 hound units and lower to the CT data sets.

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The lungs themselves are extracted from the image data.

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This threshold is applied.

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The airways are also removed from the data that is used

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to this quantification 'cause we don't wanna include the

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larger central airways and it will show us a report by lung

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or by lobe of the percent emphysema in the lungs.

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It'll give us the volume of each lobe

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and the total lung volume as well as right along together.

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So in this patient, 22%

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of the total lung volume falls in the category of emphysema.

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And this is information that is important

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to pulmonary medicine physicians

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and can also be followed over time, particularly

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as you have serial time points

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with lung cancer screening exams, uh, to look

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for progression of disease.