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Let's talk a little bit about lung nodule morphology

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and assessing the growth of pulmonary nodules in the context

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of lung cancer screening.

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We're gonna talk about looking at the images image viewing

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nodule measurement, as well as the use of AI tools

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that can augment your radiology practice

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and facilitate interpretation.

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So as we know, in CT of any kind,

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viewing is inherently multiplanar in axial sagal in the

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coronal planes for lung nodules,

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this is particularly important when nodules abut the pleural

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surface to decide if they're juxta pleural

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by nine inch pulmonary lymph nodes,

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or they're three dimensional round ovoid nodules

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that would be classified

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as such in the lung RADS interpretation schema.

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They can also help you identify the largest

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diameter of a nodule.

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It might not be in the axial plane,

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it might be in another plane.

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We measure nodules and lung rads using the slice

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or the image on which it's the largest

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and we measure the largest diameter

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and then we measure perpendicular to that largest diameter.

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So you might use these other planes beside axial

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to find the nodule at its largest.

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MIPS are helpful tool when you're scrolling

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through chest cts to identify nodule separate from vessels.

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By pulling the vessels together like a tree,

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you can see the nodule scattered

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between the branching vessels.

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In our practice we use eight Q five millimeter meps.

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Um, some practices use five Q3 millimeters

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and sometimes this is really something

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of individual practice selection.

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There are additional tools that we can use such as tools

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that will help us detect nodules, characterize nodules

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and measure nodules,

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both in two dimensional diameter and in volume.

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And by measuring the nodule over time,

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they can also look at growth rate

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and calculate that for you as the percent change in diameter

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or volume doubling time.

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These additional tools are often referred to nowadays

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as a suite of artificial intelligence tools, detection,

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characterization measurement, and growth change.

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So once you've decided that you have a nodule,

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we're gonna classify it again in that solid part, solid

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and ground glass continuum.

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Why do we classify nodules on this solid to nonsolid

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or ground glass continuum?

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Well, it's important because they have different

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lung cancer risk.

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We reflect on the work of Dr.

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Claudia Hench and David again kitz from the LCAP study.

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In their first study back in 2002, out

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of their first 1000 patient cohort of screen individuals in

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that patient population, they had 233 lung nodules.

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189 were solid, the most common being solid nodules.

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16 were part solid, the least common nodule type

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and 28 were nonsolid pure ground glass

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nodules, sometimes referred

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To as gns.

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If we look at the cancer rate amongst these nodule types,

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amongst the most common nodule type

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of solid 8.5% were cancer or 16.

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If we look at the pure ground glass nodules, five,

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were diagnosed with cancer 18%,

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but look at the percent of cancer in the part solid nodules,

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63% of the part solid nodules were diagnosed as cancer.

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So while solid nodules are the most common

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and the most easy to measure part,

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solid nodules are the least common,

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but the most likely to be malignant.

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And since the cancer probability varies by the degree

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of solid to ground glass components, that's

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how we categorize them in lung rats.

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The foundation of adenocarcinoma was revisited in the

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2011 international reclassification

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of lung adenocarcinoma.

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As a trainee, we used

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to use the term bronchoalveolar cell carcinoma.

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And with this 2011 classification that was set aside,

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we have an adenocarcinoma spectrum

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that goes from pre-invasive to frankly invasive.

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As we look at the pre-invasive lesions,

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these are pure ground glass nodules from smaller to larger.

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A small ground glass nodule about a centimeter

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to a centimeter and a half

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or smaller is known as atypical adenomatous hyperplasia.

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These are localized small proliferations

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of atypical type two pneumocytes and

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or Clara cells that line the alveolar walls

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and respiratory bronchials.

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These are pre-cancerous, pre-invasive lesions

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and present as small ggo os.

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Something that we follow nonsolid nodules when they get

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larger up to three centimeters.

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Pure ground glass nodules are adenocarcinomas in situ two

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focal solitary adenocarcinomas

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that have purely lymph growth.

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And if you resect nodules like this,

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patients will have a hundred percent disease specific

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survival, meaning that you're taking up a lot of nodules

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and the patients always survive.

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Nobody is left developing recurrence

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or metastatic disease that suggests they probably don't need

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to be taken out or don't need it to be taken out at the size

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that we have historically done.

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So today, many adenocarcinomas in situ

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to the under three centimeter pure ground glass

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or nonsolid nodules are followed serially over time looking

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to see if they develop a solid component

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and have transformed to become invasive.

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Moving from pre-invasive to invasive lesions,

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we have minimally invasive adenocarcinomas

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and invasive adenocarcinomas.

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The minimally invasive adenocarcinomas are the part solid

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nodules with a ground glass and a solid component.

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They remain three centimeters

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Or less in size

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and while they have predominantly a lipic pattern, they have

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foci of invasion.

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The solid component translates the size

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of the invasive component.

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They still do not invade lymphatics blood

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vessels or the pleura.

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They contain known necrosis

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and complete resection achieves a nearly a hundred percent

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disease specific survival,

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but not entirely a hundred percent

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disease specific survival.

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For this reason, when a pure ground glass nodule develops a

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solid component, we get concerned about it.

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These nodules are usually resected so

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that patients can have long-term survival.

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And then we get to the frankly invasive adenocarcinomas.

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A nodule like this, a spiculated lobulated nodule

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speculations extending to the pleural surface

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surrounding center bronchovascular bundles with some degree

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of architectural distortion

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and irregular looking uh, nodule.

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That's a pure invasive adenocarcinoma

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with a higher likelihood of already being spread

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to lymph nodes or beyond at the time of diagnosis.

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So this spectrum of adenocarcinoma from small

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to larger pure ground gloss nodules that are preinvasive

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and can be watched moves us to minimally invasive

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and frankly invasive adenocarcinomas as we interpret exams.

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So here's an example of a pure nonsolid nodule,

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which is minimally

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or slowly grown over serial cts

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adenocarcinoma in situ under the spectrum

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that I just described.

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This is an example of a pure ground glass nodule

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that was less than three centimeters

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and found on the baseline T zero CT

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and has remained unchanged over five

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subsequent years of screening.

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This is a pure ground glass nodule.

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It's less than three centimeters.

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It's maybe an adenocarcinoma in situ two

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or maybe the result of something else,

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but it hasn't changed.

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And even if it is an adenocarcinoma situ two,

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it is not demonstrating behavior of an invasive cancer

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and this is something that we would continue

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to follow rather than have this patient

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undergo surgical resection.

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What I mentioned we're looking

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for is going from ground glass, ground glass in this patient

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who had an unchanged nodule from baseline

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to their one year ct, but at two

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and a half years developed a solid component on top of

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that ground glass component that had been there before.

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This has shown us it's changing its behavior,

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it's developed a solid component consistent with invasion,

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and this was resected as a stage one A adenocarcinoma.

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It's important to look at not only nodule diameter

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as measured in two dimension,

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but also to look at consistency.

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But sometimes that doesn't tell us the whole picture when

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we're looking at it with our naked eyes.

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By using software that can extract the nodule

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and do those measurements, we can also look at its growth

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with greater specificity.

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Here we have a patient who had a baseline ct,

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a three month interval CT, and then one

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and two year screening cts.

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This is a 65-year-old individual

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who currently smoked on the first ct.

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The baseline measurement is 258 millimeters cubed

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at the three month interval.

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CT minimally changed with a long doubling time.

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By knowing the time difference

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and the change in volume,

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we can calculate volume doubling time.

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The volume doubling time

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of lung cancers is typically a hundred to 400 days

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with faster growing nodules, usually infectious

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or inflammatory and nodules with longer doubling times,

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usually benign in behavior.

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Notice I didn't say benign.

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It could be a dormant lung cancer that is not growing

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or doing anything invasive in the human

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in which it currently lives.

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By one year it's grown 424 millimeters cubed

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and the volume doubling time has dropped.

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It's growing faster, but it's still small in overall size.

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The patient continues in annual screening CT by two years.

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It is more than doubled in volume,

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but when you look at it on the images, it doesn't appear

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that it's doubled in diameter.

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Volume is a more sensitive measurement

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of change in three dimension over time.

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Notice the volume doubling time has now dropped to 289 days,

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which is in that range of lung cancer doubling time.

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This patient was then referred on for treatment

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and there was a typical adenocarcinoma stage one juxta.

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Pleural nodules are something that you can look for nodules

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that are under 10 millimeters in mean diameter solid

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with smooth margins and are oval lent to form or triangular

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and shape and can be on any pleural surface.

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They're considered benign lung rads two lesions.

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We used to only have this definition apply it

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to peri fist nodules such as this example on a fissure,

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but we can now apply it

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to nodules along the mediastinal pleura, the cosal pleura

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and the diaphragmatic pleura due to the extension

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of research from the original data

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that came from the Nelson trial on peri fist nodules along

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fissures to data

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that came from the LCAP study looking at costal pleural

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nodules and mediastinal

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and diaphragmatic pleural nodules, which show this,

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that when we apply these criteria,

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we can call these benign inter pulmonary lymph nodes.