0:01

So today I'm gonna talk about pulmonary nodule characterization, diagnosis,

0:05

and staging. Um, you know,

0:07

really focusing on the pulmonary nodules that end up becoming lung cancer. Um,

0:12

and the two modalities, we're really gonna be talking about our CT and PET ct.

0:16

Um, I think it's important that, you know, if,

0:20

if you are looking at pulmonary nodules, either from a,

0:24

a general radiologist standpoint or if you're a dedicated, um,

0:28

cardiothoracic or thoracic imager, um,

0:31

or if you're kind of more on the nuclear medicine side, um,

0:34

where you're reading PET ct,

0:35

it's really important to kind of integrate the imaging. Um, you know,

0:40

to come up with the best interpretation.

0:41

You really can't read either of these kind of in isolation, and you,

0:44

you have to synthesize all the information that you have together. So, um,

0:49

we're gonna kind of look at, at using the two modalities together to,

0:52

to get the best guess of what's going on with these patients.

0:56

So in terms of lung cancer imaging,

0:58

we use CT to really characterize size morphology,

1:01

look at local invasion of structures. Um, you know,

1:05

it's always helpful when you're evaluating a pulmonary nodule if you have

1:08

multiple time points and you can assess the behavior over time.

1:11

Sometimes when you see a pulmonary nodule just on one study,

1:14

it's really hard to know, you know,

1:15

is this something that's been there forever and it's unchanged,

1:18

or has this been slowly growing? Um, you know,

1:21

is this something that wasn't there a week ago?

1:23

Because that really changes your differential. Um, so, you know,

1:26

behavior over time is a big one. Uh, when you're using PET ct, uh, you know,

1:30

today I am only speaking about, uh,

1:32

18 fluoro deoxy glucose or FDG, um,

1:36

which is basically a radioactive sugar molecule and, um, you know,

1:40

is taken up by any metabolizing cells. So, you know,

1:43

obviously we have normal tissues that, um, are gonna have uptake like brain,

1:47

sometimes myocardium the GI tract. Um,

1:50

we see it being excreted renally in the renal collecting system. Um,

1:55

but we also see it with other things like infection, inflammation and cancers.

1:58

Um, so, you know, while it's not specific for cancer,

2:01

this is the primary tracer right now that we use to kind of look at the

2:05

metabolic activity of, of certain cancers. Um,

2:09

so depending on what your institution or your center does, um,

2:14

the CT portion can range from being, um, you know,

2:18

a full contrast enhanced diagnostic CT to really just a

2:23

non-contrast CT that's, um, utilized for localization and has, you know,

2:27

kind of a, a somewhat limited diagnostic value. Um,

2:32

so I think that majority of of cases, um, you know,

2:36

these are being done with non-contrast. Um, you know,

2:39

so they're not a full diagnostic value.

2:41

The other issues are that we have a very large field of view.

2:44

The slices are often thick, um, you know, five millimeters.

2:48

And to avoid misregistration, we usually take the ct, um,

2:53

with a tidal breathing technique.

2:54

And so we don't ask the patient to take a breath and hold it. We might take

2:58

The,

2:59

the CT portion as they're breathing or basically just ask them to kind of stop

3:03

breathing. Um, and the reason for that is that we collect the,

3:06

the PET data over, you know, 20 to 30 to 40 minutes,

3:10

and patient's obviously breathing through all of that.

3:12

And so if you have the patient take a deep breath and do the CT portion,

3:16

then you're gonna have a lot of misregistration. And that's, you know,

3:19

very important for pulmonary nodules, especially in the lower lobes. Um,

3:24

so PET CT provides functional information about the metabolic activity of

3:27

tissues. Um, you know,

3:28

so not only are you kind of getting an idea of what your nodule is doing,

3:31

but sometimes more importantly, we're looking for, um,

3:35

evidence of spread to the nodes, um, you know, regionally as well as distant,

3:40

uh, metastatic disease. So, as I mentioned, this isn't specific, um,

3:45

for cancer, but you know, a positive pet doesn't always equal cancer.

3:48

There's false positives, um, you know, infection, inflammation, um, you know,

3:52

being some of those. And then, um,

3:55

a negative PET doesn't always equal no cancer.

3:58

So we can have false negatives as well.

4:00

And one of the areas that we kind of really think about that are with slow

4:04

growing lung cancers, um, and very small findings,

4:07

things that are larger are gonna be more FDG avid.

4:10

And the reason for that is they have more cells with glu glute, um,

4:14

one transporters, and so they're able to take up more tracer. Um,

4:18

small findings just don't have as many cells. And so, you know,

4:21

your accumulation is gonna be different.

4:23

And so what you kind of define as positive and negative has to be taken into

4:26

perspective about size of your finding. Um,

4:30

and so one of the things that PET can be really useful for is, um, you know,

4:34

it can be helpful when your anatomic information is limited.

4:38

So if you have an endobronchial lesion and you have post obstructive collapse,

4:42

it can sometimes be really hard to tell where your tumor is.

4:45

And if you're trying to figure out how to biopsy it or how suspicious it is a,

4:48

you know, a pet can be really, really helpful. Um,

4:51

so this is an example from the literature,

4:53

which is showing a collapse of the right upper lobe.

4:55

And you can actually see this right upper lobe bronchus is basically cut off and

4:59

it's, you know, filled with something. Is it mucus and just, you know,

5:03

post obstructive collapse from that, or is it actually tumor?

5:05

So we see on the PET CT that this is, you know, very FDG avid,

5:10

it's right in the location we're expecting. And so, you know,

5:12

mucus is not gonna do this. This is a tumor with post obstructive collapse.

5:16

And so now we actually know the size of it, which is important for t staging.

5:20

We know the location, which is really important for biopsy planning. Um,

5:24

you know, so it just, it can give you a lot of information, um,

5:28

and be very helpful when the anatomy is challenging. Um,

5:31

here's a case from our institution, which you know,

5:33

is showing left lower lobe collapse. Um,

5:35

you can see there's a little bit of heterogeneity in the lung tissue. Um,

5:39

having contrast here is, is helpful. So you can kind of see some,

5:42

some differentiation, but you know, it's not exactly mass like,

5:47

but we get our pet CT and it's very easy to see where that tumor is,

5:50

what's tumor and what's post obstructive collapse.

5:55

So lung cancer imaging characteristics, um,

5:59

it's not always possible to predict the histology based on imaging,

6:02

but sometimes we have clues that kind of lead us one way or another. Um,

6:06

you know, and often this is kind of just an academic thing because, you know,

6:11

tissue is what's gonna be the most important, um,

6:14

but sometimes different out a carcinoid is helpful or, you know, if,

6:18

if you have things pointing to it being a small cell, you know,

6:22

you may wanna move faster on that patient than if you have a a low grade or well

6:26

differentiated adenocarcinoma. So sometimes it can be helpful,

6:29

but really you kind of need tissue. So these are just some clues that we, um,

6:34

you know, use to kind of predict histology, however important that is. Um,

6:39

but if something has a ground glass component,

6:41

it usually falls in the adenocarcinoma spectrum. Um,

6:44

and the ground glass component kind of represents lipic growth. Um,

6:48

when you start to develop solid components that is reflective of the invasive

6:52

component of the tumor. Um,

6:54

so adenocarcinomas can also have Arab broncho grams. Um,

6:58

that may be one clue for that. Uh,

7:00

lesions that are purely ground glass and don't have a solid component, um,

7:05

are usually characterized as these preinvasive tumors.

7:07

And we'll talk about this more in a second. Um, you know, based on size. Um,

7:12

so apical location can often be seen with squamous. It's not exclusive,

7:16

but you know, often those are squamous.

7:18

If you see cavitation invasion obstruction, um, you know,

7:23

that is often as well seen with squamous. Not always, uh,

7:27

slow growth is usually adenocarcinoma.

7:29

If you have something that you've seen developing over time, over years, um,

7:34

you know, and slowly growing, those are usually adenocarcinomas. Uh,

7:38

if you have a very small lung lesion,

7:40

but you have a lot of mediastinal disease or distant metastases,

7:44

you may wanna think about small cell,

7:46

although I feel like every time I suggest that it ends up being an

7:49

adenocarcinoma, but, you know, it's just,

7:52

it's a feature that can be seen with small cell as well. Um,

7:55

if you have a slow growing, well-defined nodule, and, you know,

7:59

your big clue here is, um, clinically in a non-smoker,

8:03

you wanna think about carcinoid tumor. Um,

8:06

sometimes endobronchial location is also a clue for carcinoids. Um,

8:11

and then I do wanna mention this dip neck diffuse idiopathic pulmonary, um,

8:15

neuroendocrine, uh,

8:17

this is like a kind of a diffuse neuroendocrine process that coats the

8:21

bronchial, um, mucosa. And you can have multiple small, um,

8:26

slow growing nodules and you usually see associated air trapping. Um, so we'll,

8:31

I have a few slides on that in the end,

8:32

it's just kind of an interesting entity that, you know, certainly, uh,

8:36

is seen in the pulmonary nodule spectrum. Um,

8:40

so looking at lung cancers size can be helpful, but, um,

8:44

you know, we'll, we'll just talk about some of these features and again, um,

8:49

they can be helpful,

8:50

but usually you have to kind of look at the whole picture altogether.

8:53

So we usually talk about nodules when they're less than three centimeters.

8:56

When they're greater than three centimeters, we usually call them a mass. Um,

9:00

when we look at nodules, we're looking at size, shape, margins,

9:04

if they have air broncho grahams, what the density is like. Um, you know,

9:08

and as I mentioned before,

9:09

sometimes behavior over time is really the most important clue. Um,

9:14

sometimes lung cancers can present as consolidations, um,

9:17

and then sometimes we have lung cancer without an actual primary lung mass,

9:22

and it can just basically arise in your mediastinal, um, nodes without,

9:26

without an actual lung mass. Um, so features,

9:30

this is from the literature, and I don't really buy into this, but, you know,

9:34

greater than three centimeters is likely malignant less than, whoops,

9:37

less than three centimeters can be benign or malignant. Uh,

9:40

I guess that's a pretty good general rule,

9:42

but we definitely see lots of lung cancers that are less than three centimeters,

9:45

especially in the advent of lung cancer screening. We, you know, our,

9:49

our goal is,

9:50

and what we are doing is detecting very small lung cancers that are more easily

9:55

treatable the earlier that we find them, patients do better. Um,

10:01

so now looking at shape, uh,

10:02

sometimes if you have a polygonal shape with multiple facets, um, you know,

10:06

flat margins that can suggest a benign etiology, especially if on your,

10:11

you know, your reformats, if something looks very flat, um,

10:15

that could be reassuring for a benign entity. Um,

10:18

if you have speculated margins, um,

10:21

that is kind of a clue that what you're looking at may be malignant. Um,

10:25

you can also see lobulated margins or scalloped margins,

10:29

and those are kind of an intermediate feature, you know,

10:31

we certainly see that with cancer,

10:32

but you can also see that with benign things like hematomas and granulomas, um,

10:38

smooth, um, this usually favors a benign entity unless it's, you know,

10:42

representative of metastatic disease. Those can be very well defined and smooth.

10:47

Um,

10:48

but if all you have is a solitary pulmonary nodule and it's got a smooth border,

10:52

um, that may represent a, a benign entity, and you know,

10:56

you probably need more workup, uh, with, you know,

10:59

some establishment of stability or behavior over time and maybe a pet as well.

11:03

So if you're not just gonna be calling something benign just based on the ct,

11:07

a lot of times do you kind of need more workup? Um, if you see an air broncho,

11:12

you know, this can certainly be seen with, uh, infection or inflammation,

11:15

but if it is a true pulmonary nodule and it has an air broncho that can favor a

11:19

malignant etiology as well.

11:22

So we're gonna spend some time on the density spectrum because I think this is

11:26

really interesting and helpful in evaluation of pulmonary nodules.

11:29

So there's kind of a spectrum that ranges from purely ground glass to ground

11:34

glass with development of some solid components,

11:36

and these can be punctate or they can be significant and be kind of the

11:40

predominant component of the nodule. Um,

11:42

you can have something that's more subs solid,

11:45

which is kind of more than ground glass, but not quite solid.

11:48

And then you can have solid. And so sometimes these, you know, you're

11:52

Catching these somewhere on the spectrum and sometimes you're watching them kind

11:56

of go from beginning to the end. Um, but this is a really great graphic.

12:01

The, um, the reference is down here, but you know,

12:04

the gray is representative of ground glass and then the white is, um,

12:08

representative of solid components.

12:10

And so here when we're less than five millimeters and we're purely ground glass,

12:14

this is AAH or atypical adenomas hyperplasia. Um,

12:18

and this is a preinvasive lesion as is, um,

12:22

adenocarcinoma in situ two, which is also purely ground glass,

12:25

but it's between five millimeters and three centimeters. Um, you know,

12:30

so this is a preinvasive lesion. Once you start to develop, uh,

12:34

punctate solid components that can become more substantial,

12:38

you're crossing over into the adeno into the, uh,

12:40

minimally invasive adenocarcinoma, and you can actually see these correlative,

12:44

um, CT images below. Um,

12:48

and so once your, um, solid component becomes substantial, um,

12:54

you know, now we're looking more at invasive cancers.

12:56

And if you have a ground glass component that can, um,

13:00

represent the lipic portion of it, and if it's purely solid speculated,

13:04

you know, you probably don't have a lipic component to it as well. Um,

13:10

and then here's just a, a graphic that kind of shows a, AH is preinvasive,

13:15

as is AIS and these are just based on size differentiation,

13:18

and then minimally invasive adenocarcinoma.

13:20

You're starting to have a little bit of invasion of these alveolar cells here.

13:23

And then, um, invasive adenocarcinoma is frank in invasion.

13:28

This is less than five millimeters. This is, um, you know,

13:30

five millimeters or greater of invasion.

13:32

That's kind of a pathologic classification. Um,

13:36

and then here's a couple examples from the literature that also show this

13:39

spectrum really nicely here. This is kind of hard to perceive,

13:43

and that's how I usually think about ground glass is you might have to mess with

13:47

the windows a little bit to be able to appreciate it, but you know,

13:50

this is a very small finding. This is AAH and then here, you know,

13:54

we're greater than five millimeters and it's just, you know, it's,

13:57

it's not the same as the surrounding tissue, but it's, you know,

14:00

still difficult to see. Um, now, you know,

14:04

we're starting to see it a little bit better.

14:06

You kind of wonder if some of these little punctate things are, you know,

14:09

solid components or are they vessels running through it, but you know,

14:13

this one kind of doesn't look like a vessel. And then here, you know,

14:16

we're kind of moving along the spectrum. We're really starting to see, you know,

14:19

more definable central solid components. Um, you know, and,

14:24

and so this is kind of moving into your minimally invasive category.

14:28

And then here, you know, the ground glass margins on this are,

14:31

are kind of hard to see, but we definitely have solid component, right?

14:35

Same thing going on here.

14:36

We have solid component centrally and we've got this kind of lipic halo around

14:40

it. And then here we've got something that's really pretty much purely solid.

14:44

And, you know,

14:45

these are some graphs just basically showing that the degree of invasion

14:49

increases with more solid tissue that you have. Um, you know, so it's,

14:53

it's really interesting when you see these nodules and you go back to your

14:56

priors,

14:57

you can often see them kind of crawling along this spectrum and you go back and

15:00

you, you know, can see that they started as a ground glass nodule.

15:06

Um, so here's just some more examples.

15:08

We're gonna kind of go through each class, but um, you know, using density.

15:11

So here's a purely ground glass nodule, you know, you can see it,

15:15

but it's a little bit hard to see. This is the axial and the coronal. Um,

15:19

this one would fall into the, um,

15:21

the AIS spectrum based on the size because it's bigger than five millimeters.

15:27

So, you know,

15:28

kind of moving from CT to pet and sometimes pets get done For these, um,

15:32

you know,

15:32

theoretically you really should only be doing pets in patients that have a solid

15:36

component greater than seven or eight millimeters.

15:38

That's kind of the lower limits of size resolution for pet. But you know,

15:42

sometimes the report just gets put out that, oh,

15:45

there's a one centimeter ground glass nodule and they get, you know,

15:48

they get set for pet. Um, so in these purely ground glass ones,

15:52

you are often gonna have like little or no FDG uptake.

15:56

You can see the window really cranked on this and you can barely perceive,

15:59

you know, a little area of uptake. Um, you know,

16:02

we've seen this nodule in 2015 was very small, maybe at the five millimeters,

16:07

you know, has certainly increased in size.

16:09

You can see there's a little bit of distortion of the major fissure,

16:13

kind of at the posterior aspect.

16:14

So we know that this based on CT is an adenocarcinoma spectrum lesion.

16:19

And you know, there's probably some development of solid component in there. Um,

16:23

you know, so this may be kind of crossing into the MIA, but you know,

16:27

it's mostly ground glass nodule, barely perceptible. So like I said,

16:31

small things are gonna be less avid. Um,

16:33

only your solid component is really gonna demonstrate uptake.

16:36

Sometimes you see a little bit with the ground glass, but um, you know,

16:40

when I read these and they're barely perceptible, I give an SUV max,

16:44

which is usually very low. Sometimes it's one or even less than that.

16:47

And as a reference,

16:49

I'll give the background long SUV in kind of a mean to max range that even

16:53

though it's low, it's not necessarily negative, you know,

16:56

so it might be two times background or one, one and a half times background,

16:59

but you know, when somebody reads a report with an SUV max one,

17:03

that doesn't sound very impressive, right?

17:04

So having the background can be helpful. Um,

17:08

so here we are moving kind of more into the AIS slash I

17:13

and sometimes when I'm reading these and you know,

17:16

they're kind of on the border, I do give both of these because you know,

17:18

it's a pathologic diagnosis and not radiologic.

17:21

So here we can definitely see some development of punctate solid component.

17:25

Here's the axial, here's the coronal, but you know,

17:27

it's still a mostly ground glass nodule, but it does have solid component. Um,

17:32

you know, so if it's punctate, you know, you're kind of just at this, you know,

17:35

AIS slash MIA, if it's substantial, you're minimally invasive or you know,

17:40

potentially just frank, frankly invasive adenocarcinoma,

17:43

depending on how much solid component you have. Um, behavior.

17:47

These are usually slow growers.

17:49

They usually start out ground glass and then start to develop the solid

17:52

components. Um, here's another one.

17:56

Ground glass with solid components. And so you can see it by, um, you know,

18:00

by ct we've got this lipic halo to it and this central solid component and you

18:05

know, not all that impressive on pet, but it's not negative, right?

18:09

We definitely can appreciate some uptake here.

18:11

So these kind of what you're expecting to see on PET is barely perceptible,

18:16

faint mild uptake, maybe a little bit more. Um, you know,

18:21

and this qualitative assessment is important to give, um, you know,

18:24

because your numbers might not be that impressive. So again,

18:28

PET is really ancillary. You should, um, you know,

18:31

make up your mind based on the CT of these because, um, you know,

18:35

if you're reading this PET in isolation,

18:38

you're not gonna be that worried about this finding because it's not

18:41

particularly FDG avid, it doesn't look metabolic or aggressive,

18:46

but you know,

18:47

kind of keeping in mind what the CT appearance is when you put all of these

18:50

pieces together, this is definitely a cancer, right?

18:53

And we don't wanna sit and watch these, um,

18:57

grow because the earlier that we can intervene, the better,

19:01

the easier the surgery is and the better the outcomes the patients have. So, um,

19:06

you know, really these need to all be read together. Um,

19:10

so I'm just gonna mention a note on the T stage also, um, you know,

19:14

based on the AJCC eighth edition, um,

19:17

T stage is really a measurement of the solid components.

19:20

So when you're reporting these, um, you know, at the workstation,

19:24

you do wanna give an overall measurement because that's important for surgical

19:27

planning,

19:28

but you also need to kind of specifically mention what the solid component, um,

19:32

measures because that is what t staging is based off of.

19:37

So here's another example. Um, you know,

19:40

we have studies from 2016 and 2017,

19:43

and you can see that this is a mostly ground glass nodule.

19:47

There may be some punctate solid components, but you know,

19:50

by 2017 we definitely have developed development of a more substantial, oops,

19:54

sorry, substantial central solid component.

19:57

And so the PET CT in 2016 really is negative. You know,

20:01

you don't appreciate any uptake there,

20:03

but by 2017 we're starting to see a little bit of warmth on the pet and that,

20:07

you know, is representative of this development of solid component. So again,

20:12

if you're reading this pet by yourself, you're, you know, kind of like, oh,

20:15

this is not very impressive. And some people might even call this PET negative,

20:19

but we know based on the CT that this is a developing cancer.

20:25

Alright, so here's kind of this sub solid category. So, um, you know,

20:29

we're looking, we'll just kind of focus on the, the highest one here at, um,

20:33

in from 2018. And it's more than ground class, right?

20:37

There's like, it's, it's easy to see, you don't have to play with the windows.

20:42

There's kind of like this interspersed solid component with maybe a little bit

20:46

of crown glass, but you know, it doesn't fit the,

20:48

the classification for ground glass, but it's also not quite, you know,

20:52

densely solid like, you know, we see with some pulmonary nodules.

20:55

So those are what I call, you know, and people classify as subs solid. Um,

21:00

you know, they're more density than ground glass,

21:02

not quite solid a conglomerate of punctate solid components. Um, you know,

21:06

but any indication of the solid component is reflective of some degree of

21:12

invasion. Um, and so FDG evid on pet, you know,

21:15

kind of guessing what you're going to see,

21:17

it really just depends on how much is solid. But you know, again,

21:19

these aren't densely solid,

21:21

so these are usually kind of low more lowly FDG avid,

21:24

but more in the minimal to mild spectrum or sometimes, you know,

21:27

kind of moderate. Um, so here's,

21:31

we can definitely see from 2016, this started out as, you know, a small nodule,

21:37

probably a little bit more than ground glass, but you know,

21:39

it's definitely increasing in size. But you know,

21:41

also important to note is that it's increasing in density and solid component.

21:45

You know, and this is pretty easy to see on the PET ct, right?

21:49

And that makes sense because we have a little more solid component than we had

21:52

on the previous cases. Here's another example. Um,

21:57

you know, again,

21:58

like this is starting out in 2014 as a pretty small right upper lobe, um,

22:03

plural based abnormality and it's, you know,

22:05

it's a little bit more than ground glass, right?

22:08

The density is just a little bit higher and it's definitely increasing in size

22:12

and you know,

22:12

the margin there is in some areas a little bit like harder to kind of delineate,

22:17

but, you know, sharpen other ones. Um, and here's the PET ct,

22:21

really kind of not impressive, but not negative. Um, you know,

22:24

which makes sense because we don't have a lot of like obvious solid component in

22:29

this nodule. Um, here's another 1, 20 13.

22:34

This is, you know, negative. There's nothing on the ct.

22:36

We've got development of this kind of sub solid looking nodule in 2014

22:41

and by 2016, you know, it's definitely made itself apparent. You can see some,

22:46

um, distortion and tethering of the adjacent major fisure. And then, you know,

22:50

this is pretty easily seen by PET as well.

22:55

So solid nodules. Um, these can be round, these can be s speculated.

23:00

Um,

23:01

these tend to grow faster than ones that have significant solid component,

23:06

um, you know, or the subs solid nodules. So we can see 2016 to 2018,

23:10

this started out, you know, fairly solid. It's, you know, growing,

23:14

it's got lobulated and spiculated borders and you know, again,

23:18

definitely increasing in size and you can also see again,

23:21

a little bit of fish oil distortion. Um,

23:24

so pet cate really easy to see this, right?

23:27

So these are kind of usually more in the moderate to intense, um,

23:31

degree of FDG uptake. Uh, when you look at these on pet,

23:37

um, you know, classically increased. And so, um, you know,

23:42

sometimes squamous cells tend to be more FDG avid than adenocarcinomas.

23:47

It's not a hard and fast rule, but you know, um,

23:50

if you see something looking very like metabolically um, aggressive,

23:54

then you know, it might end up being a squamous cell carcinoma. So like we said,

23:59

usually moderate or more. Um,

24:02

and so I've been kind of using these qualitative descriptive terms of barely

24:06

perceptible, minimal, mild, moderate and intense.

24:10

And I think it's important to give that in addition to your actual SUV

24:15

max number because, you know,

24:17

if you have an SUV max in a five,

24:20

a five and a five centimeter mass, that's, you know,

24:24

kind of not that impressive, it's probably gonna be moderately f dg avid. Um,

24:29

but if you have an SUV max of a of five in a sub centimeter nodule,

24:34

that's gonna look like really intensely FDG avid.

24:37

And so when you give that qualitative assessment, it kind of helps correct for,

24:42

um, you know, how many cells you actually have there. So, you know, uh,

24:46

you might have, um,

24:48

a small pulmonary nodule measuring less than one centimeter and an SUV max of

24:52

2.5 and it might look very, very intense just because it's such a small finding.

24:57

Um, so I find those helpful to kind of gauge the,

25:00

the behavior and I think it's helpful for the clinicians to kind of, um,

25:05

have an idea of, of perspective based on the size. Um,

25:09

here's another case of a classically, you know,

25:12

solid nodule and it's intensely FDG, AVID by by pet.

25:17

Um, so here's an example. We've got, um, you know,

25:22

a earlier study which shows just like a very small pulmonary nodule in the

25:26

subpleural left upper lobe. Um, and we can see on follow-up,

25:30

I think this was two years later, that, you know,

25:32

this finding has definitely increased in size and it's like kind of, you know,

25:37

got a substantial solid component. It's really mostly solid or you know,

25:41

some might argue it's got a subs solid component, but you know,

25:44

we are worried about this, right?

25:46

We have it in two time points and it's definitely grown.

25:50

So we do a pet CT and it's not very impressive, right?

25:56

So usually at this point I ask the residents, what do you guys think? Like,

25:59

is this something to worry about? Is this a cancer? Should we, you know,

26:03

really be reassured by this pet? And the answer is no. Um,

26:08

you know, this has an SUV max of 1.5, so background is 0.9,

26:13

so it's not even twice background, but you know,

26:16

this ended up being a well to moderately differentiated adenocarcinoma.

26:21

And so this is kind of one of your classic, like, you know,

26:25

that we hear about false negative pet su teas and you know,

26:28

if the histology is very well differentiated or moderately differentiated,

26:33

you know, that means that these,

26:35

these cells aren't as rapidly turning over and as metabolic as you know,

26:39

your poorly differentiated, um, cells. And so, you know,

26:44

you should not be reassured by a benign looking pet in this case because

26:49

we already have the evidence that this is a growing abnormality and that this

26:52

is, this can't be anything other than a cancer.

26:54

So that's why it's important to really kind of make up your mind on the ct. And,

26:58

you know, you cannot read the PET CT in isolation.

27:02

You really have to put everything together. So if our,

27:05

if I were reading this PET ct, I would say, you know,

27:08

despite the low level or the barely perceptible FDG uptake in this nodule,

27:13

the morphology and growth over time remains highly suspicious for an invasive

27:18

lung neoplasm. Um,

27:23

so just some other cases where, you know, pulmonary nodules, sometimes you,

27:27

you get, uh, a history of a pulmonary nodule and it's, you know, it's not,

27:31

it's comes through as like a mass or a consolidation or something like that.

27:34

But, um, here's just some other examples of how, uh, lung cancers can present.

27:39

You know, this is a solid, uh,

27:41

apical mass and you can see that there is some invasion into the chest wall and

27:45

erosion of the adjacent rib. Um,

27:47

here's the soft tissue in the lung windows and then here's the PET ct and it's,

27:51

you know, intensely FDG avid, which we expect to see. Um,

27:55

it's kind of got an elongated shape. Um,

28:00

here's one that has cavitation and um, you know,

28:03

also has speculations, you can see it's tethering, the fissure, which, you know,

28:08

I think this is a really important clue to kind of help you differentiate

28:11

between infection and inflammation in tumors. Um, you know,

28:15

usually the speculations from tumors are, um,

28:20

some degree of fibrosis and traction and pulling in,

28:24

whereas when you have infection or inflammation,

28:27

you actually have puss kind of filling the air spaces and being a more of a

28:31

space occupying lesion. And so generally speaking,

28:35

infection and inflammation don't result in fial distortion or tethering.

28:39

So if you see that and you have, uh, you know,

28:42

something in the lung that you can't really tell, is it infection?

28:45

Is it inflammation? Is it tumor? If you see any of this architectural, um,

28:50

distortion of the fissures or tethering, you should really kind of be very,

28:55

you should be worried about a, um, a cancer there. This is, uh,

28:58

a squamous cell carcinoma and we kind of have a clue for that because we do have

29:02

some cavitation and here it is on PET CT as expected to be, you know,

29:07

very FDG avid. Um,

29:11

so sometimes you can get really unusual shapes. Um,

29:14

and so when you have a patient that has, uh, background emphysema,

29:19

the normal architecture of their lung is no longer kind of what we expect to

29:24

see. They have holes and bolus changes, um,

29:28

scarring traction.

29:30

And so sometimes you get lung cancers that really kind of look strange and they

29:35

can, they can have weird shapes or they can have, um, you know,

29:39

they can kind of occur along the edge of Ebola,

29:42

and so they're kind of almost sheetlike. Um,

29:44

but that's basically because your background architecture is abnormal. Um,

29:49

you know,

29:50

so this one is an example of a case where I think there was a large Ebola kind

29:54

of right underneath this, and it was kind of extending along, um,

29:59

along the edge of it, but kind of a, a strange finger-like projection. It's,

30:02

you know, not always classically your round or lobulated mass. Um,

30:07

another thing to be aware of is development of carcinoma within a scar. Um,

30:12

and so this was a case from our institution from, um, 2018,

30:15

which there was a longstanding scar in this left upper lobe and you know,

30:20

it's pretty stable between 2018 and 2019 and then started to develop a little

30:25

bit of kind of nodular, um, shape to it and, uh,

30:29

pet CT was done and, you know, it showed a little bit of uptake,

30:32

but this was biopsied and this was, you know, cancer developing within a scar.

30:36

Um, so, you know, it's important to kind of like look at those, uh,

30:41

critically and carefully when you're reading your chest cts. Um,

30:45

sometimes lung cancers can present as consolidations,

30:48

and these are really challenging for us as radiologists because, um, you know,

30:52

we probably most of the time are gonna call these infection or inflammation

30:57

and you know, 95% of the time we're gonna be correct. Um,

31:03

you know,

31:03

but this is one of the reasons that we kind of recommend follow-up imaging after

31:07

cases of pneumonia to really make sure that this goes away. Um,

31:10

and so clues if you have persistent consolidations that don't, um,

31:16

that don't resolve or at least improve on follow-up imaging and you know,

31:20

especially if they're being treated with antibiotics or antifungals or,

31:24

you know, whatever is deemed clinically appropriate.

31:27

If you have patients that are not responding appropriately, then you know,

31:30

cancer should be kind of creeping up on your radar. Um,

31:34

often these are diagnosed on bronchoalveolar lavage and you know,

31:38

that's because clinically they're also not improving and they want to, you know,

31:43

get a sample and isolate an organism so that they can tailor their antibiotic or

31:47

antifungal treatments. But, you know,

31:49

sometimes they get surprised and it ends up being a cancer. Um,

31:54

here's another case that we had from our institution and, you know,

31:58

kind of interestingly,

31:59

this patient has sinus versus you can see reversal of all of the organs, but,

32:03

um, you know,

32:04

these seemingly innocent looking consolidations that most patients would be

32:08

infectious or inflammatory ended up being, um, adenocarcinoma.

32:13

Here's another one. Um, you know,

32:15

these are four different time points we've got, uh,

32:20

sorry, yeah, four different time points ranging over like six months.

32:23

And you can see that this consolidation is, you know, kind of getting worse.

32:28

Um, this is the earliest, this is the next,

32:30

this is the follow-up and this is the most current and, um,

32:34

pet CT done at two different time points.

32:36

Just kind of shows this low level FDG uptake, which is not, you know,

32:40

particularly suspicious or, um, or, uh,

32:45

specific for tumor. You know, ordinary pneumonias can certainly look like this.

32:49

So these ones are tricky. Um,

32:53

this was another consolidation in the right lung which, um,

32:55

ended up being squamous cell carcinoma. You know,

33:00

you look at this on pet and this is pretty FDG avid, this,

33:04

this might make you wonder, is this actually a cancer? Um, you know,

33:08

just because usually pneumonias are not so well-defined,

33:12

they have very heterogeneous uptake. Um, you know,

33:15

and they may not be this FDG avid, uh, you know,

33:19

and we definitely have nodal involvement here, and not just ipsilateral,

33:22

we have contralateral nodal involvement as well, which is important for staging.

33:27

Um, so just some notes on carcinoid. Um, like I mentioned before,

33:30

clinically a clue for these, um,

33:32

is if you're seeing pulmonary nodule in a non-smoker, um,

33:37

these are usually solid kind of well-defined sharply demarcated borders. Um,

33:42

they're often very, very slow growing.

33:44

If they are your usual typical carcinoids, um, you can have,

33:49

uh, a malignant degeneration into an atypical carcinoid,

33:54

and we'll kind of talk about that in a second. But, um,

33:57

sometimes these can have calcification. Um,

34:00

so there are two PET scans that we can use for, uh, for carcinoid. So,

34:05

you know,

34:05

often these are detected incidentally or a pet is done because it's a solid

34:09

pulmonary nodule. Um, you know, your usual 18 FDG pet.

34:14

Um, and so really the uptake depends on metabolic activity.

34:18

So if you have a well to moderately differentiated or typical carcinoid,

34:23

you're really not gonna have a lot of uptake on FDG PET because these are very

34:27

kind of slow growing, um,

34:31

nodules in cells that you know are not particularly metabolically avid.

34:36

Um, and so when you have poorly differentiated histologies or really aggressive

34:41

appearing, um, atypical carcinoids,

34:44

then FDG is gonna show higher uptake. Um,

34:47

so the other tool that we have in our toolbox and we do here at UMass is a 68

34:51

gallium, um, Dotatate PET ct. Um,

34:55

and so this is a little bit different of a mechanism of, of action for uptake.

34:59

So we talked about FDG being a radioactive sugar molecule,

35:03

and it's basically taken up by metabolizing cells. Um,

35:07

the dotatate is, uh, a receptor to somatostatin or, um,

35:12

it binds to somatostatin receptors, which are expressed on, um,

35:16

the surfaces of neuroendocrine tumors. Um,

35:20

and so the more well behaved or well differentiated

35:24

the, um,

35:26

neuroendocrine tumor is the more somatostatin receptor expression it will have.

35:31

And as these tumors degenerate or become poorly differentiated,

35:35

they lose their somatostatin receptor expression.

35:38

So it's kind of the inverse where you have, well,

35:41

to moderately differentiated tumors will demonstrate very high uptake.

35:46

Um, and so if you have a lot of uptake that is reflective of like a well-behaved

35:51

typical carcinoid,

35:53

if you have poorly differentiated or aggressive histology,

35:57

atypical carcinoids, then you may see low uptake on,

36:01

on dotatate pet. So some places really kind of use these together,

36:06

um, you know,

36:07

to kind of put the pieces together and figure out what kind of cells you have

36:10

based on how much uptake there is on the gallium dotatate versus, um,

36:15

FDG. So here's an example for our institution. This, um,

36:20

was an older woman who had had a history of an endobronchial carcinoid on the

36:24

right, and she was, uh, she was treated with, uh,

36:28

debulking and radiation. Um, she was becoming more symptomatic.

36:33

This was, I think five to seven years after treatment. Um,

36:36

she was becoming more symptomatic and by ct she was having kind of more collapse

36:40

of her lung. And so she underwent bronchoscopy and lo and behold,

36:45

they found, you know, recurrence of her tumor, endo bronchioli. Um,

36:49

they cut away as much as they could to kind of clear out the bronchus,

36:52

but it was really hard to tell based on bronchoscopy and also based on ct.

36:57

You know, how big is this recurrence? How extensive is it? It,

37:01

is it because we're really kind of in this post-radiation field and it's,

37:05

you know, kind of impossible to see. Um, so she underwent dotatate scan,

37:10

um, oh,

37:11

and I forgot to mention the histology from her original and her recurrence was

37:14

well differentiated or typical carcinoids,

37:16

which is really what most of them are. Um,

37:19

and so you can see on her Dotatate PET ct,

37:21

she had this like flaming hot area of uptake mass, like, and, you know,

37:26

very easy to see where her tumor is. Um, and in addition,

37:31

we actually see that she had two liver metastases and um,

37:35

a bone metastasis as well, um,

37:38

that were occult by CT imaging. Um, you know,

37:42

so this is a really great tool to have in imaging of neuroendocrine tumors, um,

37:46

you know, both in the abdomen and pelvis, but also, you know,

37:49

using for pulmonary carcinoids.

37:54

Uh, here's another case where a patient had two, um,

37:58

had two pulmonary nodules. One was kind of in the, uh,

38:01

in an end bronchial location and one was, um, posterior to it.

38:05

So they had had an FDG PET CT showing, um, you know,

38:09

kind of mild uptake in, in this lesion,

38:12

but no uptake in the other lesions. So, um,

38:16

the more posterior one was biopsied and it was a mucinous adenocarcinoma.

38:21

Um, and so then this one was, um,

38:25

investigated by a bronchoscopy and came back as carcinoid.

38:29

So she underwent the dotatate pet, and you know, you can see this tumor very,

38:33

very well. Um, you know, it's intensely do, um,

38:37

intensely dotatate avid and consistent with carcinoid. And then, um,

38:42

you know, in addition,

38:43

she had kind of another nodule that was buried in some ectasis,

38:47

which showed that she actually had two carcinoid tumors.

38:49

So this is an interesting case,

38:51

so somebody with carcinoid and kind of your usual lung cancers, um,

38:56

you know, in the same setting. So dip neck,

39:00

which we talked about before,

39:01

diffuse idiopathic pulmonary neuroendocrine cell hyperplasia. Um,

39:06

so this process actually kind of coats the entire bronchial mucosal epithelium.

39:10

Um, and it's not, you know, inva invading the basler level.

39:15

And so this is on the neuroendocrine proliferation spectrum and it's kind of on

39:19

the benign end. Um, you know, and when you have these nodules,

39:24

they're typical carcinoids. Um, so the classic patient is a non-smoker,

39:28

middle-aged female, um, history of chronic cough or asthma.

39:33

Uh, and you know, these can be, uh,

39:36

or this condition can be a precursor to these peripheral carcinoid tumors,

39:40

which are not uncommon to see in this condition. Um,

39:43

it's relatively indolent and it's usually stable over years. But, um, you know,

39:47

you can have the potential for these to, um, de differentiate, uh,

39:52

undergo malignant transformation to atypical carcinoids.

39:55

They can meta to metastasize to local regional lymph nodes and, you know,

40:00

kind of occasionally to extra thoracic sites. Um, you know,

40:05

so generally speaking, because it's such a diffuse process,

40:08

there's really not a good treatment for it because it's kind of impossible to

40:13

treat the entire bronchial mucosa. Um,

40:16

so it's generally watched and then as nodules pop up or become,

40:21

um, you know, problematic or symptomatic, then you know,

40:24

they're kind of dealt with individually. Um,

40:27

so by CT you're gonna see slow growing nodules.

40:30

They may be kind of stable for many years. Um,

40:33

and you'll see findings of asthma, small airways disease,

40:36

you can see some air trapping, um, on, on this ct.

40:39

And you can sometimes see bronchial wall thickening as well.

40:41

So if you kind of see the, that combination of findings,

40:45

you wanna think about dip neck. Um,

40:48

so Dotatate PET CT has been looked at, um, in this condition and it's, you know,

40:54

not usually helpful in the small nodules, just, you know, because they're, um,

40:59

you know, if they're small, if they're under ACE a centimeter, um, you know,

41:02

you can kind of confirm that you have neuroendocrine cells there. Um,

41:07

you know,

41:07

but it can be helpful if you're trying to determine if one of the nodules is

41:12

undergoing malignant degeneration. Um,

41:15

and so if you have a sizable tumor that is changing by CT and you're kind of

41:19

worried that there's malignancy degeneration and you do a dotatate scan,

41:23

if there is poor uptake in that, then then you're gonna be worrying about,

41:28

um, transformation to atypical carcinoid. Um,

41:33

so we have a, an example, this is from the literature here, and you can see,

41:38

you know, this is a, um, let's see,

41:42

this is a comparison of DOTATATE and FDG. Um,

41:46

so these are two different time points, but you can see FDG, um,

41:50

is showing a little bit of more uptake in this tumor than, um,

41:55

it is on the dotatate. Uh, and we also have, um,

41:59

new right upper para tracheal lymphadenopathy, which is also FDG avid.

42:04

So this tumor was changing over time,

42:06

not very impressive on the dotatate is showing some uptake on the FDG pets.

42:10

So kind of putting all of those together is worrisome for, um,

42:15

you know, malignant degeneration. Um,

42:18

this is a case that we had here at UMass, and these are not the same time point.

42:22

This is 2014 and this is 2019.

42:25

But I think it's still interesting to look at because if you look at the

42:28

nodules, they're really not changed. Um, and so it, you know,

42:33

even though they're five years apart, this is a very stable and, you know,

42:36

indolent disease. And so you can see this nodule here, um,

42:41

on FDG is, you know, kind of barely perceptibly FDG avid and then,

42:45

you know, same size nodule several years later.

42:48

But you can just see how much better it's seen on the Dotatate PET CT because

42:52

that tracer is very specific for this kind of tumor. Um,

42:56

there's another kind of, um, nodule along the,

42:59

per the bronchovascular bundle on the right and um, you know,

43:02

this one maybe is increased by a millimeter or two over the five years,

43:05

but you know, again, not very impressive by FDG, but you know,

43:09

certainly well seen on the, um, on the dotatate,

43:12

and you can actually see an adjacent lymph node as well.

43:17

Um, so just one note on small cell. Um,

43:19

this is an example of having a small primary and, you know,

43:23

really diffuse metastatic disease. A lot of mediastinal lymphadenopathy,

43:28

the liver is just loaded with metastases.

43:30

We've got bone mets kind of all over and, you know, other,

43:33

other lymph node stations involved as well. Um,

43:38

and then some notes on staging. Um, you know,

43:41

the staging of small cell cancer is, you know, uh,

43:45

it's localized or extensive stage. Um, and so localized is,

43:50

uh, confined to a single radiation port, um,

43:54

confined to the ipsilateral mediastinum. Um,

43:56

or you can have ipsilateral mediastinal and supraclavicular nodes.

43:59

So really anything that is outside of this is, um,

44:04

defined as extensive stage.

44:06

And then for non-small cell lung cancer, this is a huge, you know, um,

44:12

graphic here. These are both from radiographics, but um, you know,

44:15

nobody needs to memorize these, but you should be familiar with, um,

44:21

you know, kind of general guidelines about sizing and, you know,

44:25

involvement of certain structures that will upgrade tumors.

44:28

Because when you're reading the cts or the PET cts on these, um, you know,

44:33

in order to accurately stage the patients,

44:35

you have to give them all of the tools to be able to do that. So, you know,

44:39

there's cutoffs at, you know, three centimeters, three to five centimeters,

44:43

five to seven centimeters or greater than centimeters in the long axis.

44:47

And you know, when you're, when you're reading these, um, you know,

44:51

it's tempting to just get your measurements off the axials,

44:53

but you really should look at all your reformats and find the longest dimension

44:57

of the tumor, um, because that's gonna give accurate t staging. Um,

45:02

and then, uh, you know, also you wanna look for things that will upstage. So,

45:07

you know, invasion of chest wall, frantic nerve pericardium, um,

45:12

you know, if you have satellite nodules, uh, you invasion of the carina,

45:16

the trachea, great vessels, um, you know, an adjacent vertebral body.

45:21

So just when you're reading these are kind of pertinent positives and negatives.

45:25

You don't have to list everything if it's a small tumor,

45:28

but if you have a large tumor that's, you know,

45:30

kind of next to other structures, these are pertinent, um,

45:32

things to be looking at. Um,

45:36

so as for nodal staging, you know, N zero, no nodal metastases,

45:41

N one is ipsilateral para bronchial hilar nodes, um,

45:45

or intra intra pulmonary nodes.

45:47

So this is like pretty limited to the hi everything that's in the hilum and

45:51

distal to that towards the tumor.

45:53

And two is where you start to have mediastinal nodes, but um, or SubCal nodes.

45:57

But all of the mediastinal nodes need to be on the same side as the tumor. So,

46:01

you know,

46:01

ipsilateral adenopathy is an N two when you start to get contralateral

46:06

lymphadenopathy, whether it's in the mediastinum or in the hilum. Um,

46:10

if you have scaling or supraclavicular nodes that up upstages you to an N

46:15

three. And then, you know, metastatic disease,

46:19

we kind of all all know about that m staging as well.

46:24

Um, so this is just kind of broken down, um, from that,

46:28

that graph.

46:29

We won't spend the time going through this 'cause we're kind of coming up on the

46:32

end, but, um, you know, if you have a locally invasive tumor,

46:36

it's important to look at which structures it's invading. Um,

46:40

one note about, uh, lymphadenopathy,

46:44

the right lower para tracheal nodes can sometimes be kind of

46:48

anteriorly located and sometimes people call these pretracheal and that's not

46:52

actually a real station. Um,

46:54

and so if you look at the left lateral border of the trachea,

46:59

that's actually what delineates midline.

47:01

So anything to the right of the left lateral border is considered

47:06

like to the right.

47:07

So these pretracheal nodes are actually right lower pair tracheal,

47:11

and that's, you know,

47:12

important because if you call it a left when it's really a right,

47:15

you're moving from N one to n or sorry,

47:18

n two to n three in some cases. Um, let's see.

47:24

Yep, this is just all kind of stuff that was in the chart before. Um,

47:29

and these are some questions I asked at from our tumor board group about just

47:32

what are important,

47:33

really important things for other people on the cancer care team to know. Um,

47:38

you know, and so pertinent information for the thoracic surgeon,

47:41

they really wanna know about vessels. Um,

47:43

they wanna know about the degree of encasement.

47:46

If there's evidence of wall irregularity, they need to know if they,

47:49

if there are other types of surgeons they need to involve in,

47:52

in their particular procedure. Um,

47:55

they also wanna know if it's crossing a fissure. Um, you know,

47:59

that can be important because if they're planning to do a wedge or a lobectomy

48:04

and they need to take extra lung from another lobe, um,

48:08

they need to know if that's acceptable for that patient based on the lung

48:11

function. And, you know, for surgical planning, obviously, um,

48:15

they want to know the distance of tumor from the Karina if there's, you know,

48:19

endobronchial or direct invasion. Um,

48:22

although sometimes this is better evaluated by bronchoscopy,

48:24

but we should really do our best on the imaging to give them that information.

48:28

Um, they wanna know if there's chest wall invasion, um, you know,

48:31

for pleural based masses,

48:33

does it look like there's anything kind of extending beyond the pleura?

48:36

Are there changes in the wall, in the chest wall or nearby ribs? Um,

48:39

they need to know this for reconstructive implications and obviously, you know,

48:44

surgical planning. Um, so radiation co uh,

48:48

oncologists, they wanna know about the nodes. That's a big thing for them. Um,

48:52

they also wanna know if there's anything that they should be kind of urgently

48:56

treating. Um, SVC syndrome is a big one. Um,

48:59

any compromise of airway or major vascular structures, um, you know,

49:04

whether it's actively occurring or if it's, you know, impending in a,

49:07

in a quickly growing tumor. Um,

49:10

they wanna know if there's other pulmonary nodules and what the location and

49:14

distance from the primary tumor are because if they're gonna be treating

49:17

something with radiation and there's another nodule that's potentially

49:21

suspicious and it's easy to include in their radiation field,

49:24

then sometimes they may wanna just empirically treat that. Um,

49:28

they also wanna know if there's any neurologic involvement spine. Um,

49:32

that's something that they can kind of treat on an urgent basis,

49:35

any invasion into the neural structures or spinal canal, any um,

49:40

stenosis from that. Uh, and you know,

49:42

they wanna know about metastatic disease too,

49:43

because they're not gonna apply local primary treatment to a lung cancer

49:49

if it's not a local issue.

49:50

They may do local palliative radiation to kind of help with symptoms,

49:54

but they won't use radiation as a primary treatment if, you know,

49:58

there's metastatic disease in most cases. Um,

50:02

so for the interventional pulmonary pulmonologist, they wanna know about,

50:06

you know,

50:06

distance in relationship to airways and bronchial structure structures.

50:10

You know, often this is kind of in the prediagnostic phase, they wanna know,

50:14

can I reach this nodule via bronchoscopy? Um,

50:18

and are there nodes that I should be sampling while I'm in there? You know,

50:21

which are all practical considerations.