0:00

Let's look at this lung cancer screening CT from the

0:03

perspective of other findings than those that are concerning

0:07

for early lung cancer.

0:08

This is a 61-year-old man with a 20 pack year history

0:12

of cigarette smoking who no longer smokes.

0:14

He has a history of coronary disease

0:16

and has been in the emergency department recently

0:18

and had two coronary stents.

0:21

As we're scrolling down the lungs,

0:22

we see already subtle reticulation around the lateral

0:26

and posterior of the lungs bilaterally.

0:29

Normally, the interface between the lung

0:31

and the pleural surface as we see anteriorly here, is very,

0:35

very smooth, very, very smooth.

0:39

A balloon of air-filled lung tissue against a smooth pleural

0:42

surface should look nice and smooth.

0:45

But when you have interstitial lung abnormal,

0:47

these these little lacy lines, that interface starts

0:50

to look very ratty and irregular

0:52

because essentially you're silhouetting the continuous

0:55

tissue between the lung parenchyma

0:57

and now the pleural surface and extra pleural tissue.

1:00

So that ratty pleural edge is evidence that

1:03

what we have is underlying fibrotic lung disease.

1:06

Notice when we have dependent emphysema,

1:08

we don't blur the edge as much

1:10

as we see when we have these lace reticulations.

1:14

As we continue scrolling down the lungs,

1:17

we see more reticulation in the posterior basal lower lobes

1:21

as well, and we start

1:23

to see very mildly dilated bronchi in the peripheral edge

1:26

of the lung where we should not see any

1:29

normal airways at all.

1:32

So this is early evidence of interstitial lung disease.

1:35

We can look at this more clearly with an HRCT

1:39

to better see particularly small areas of bronchiectasis

1:44

and to see tiny areas of honeycombing.

1:47

For instance, we see a little tiny loosen cluster here

1:49

on the screening ct.

1:51

I don't think I can be confident as to whether I call

1:54

that honeycombing or not,

1:55

but I can be confident enough

1:57

to know we have early fibrotic interstitial lung disease

2:00

here, and it's important that the patient be evaluated

2:03

with pulmonary function tests

2:05

and referral to pulmonary medicine.

2:07

Oftentimes when we're looking at these cts, we can just

2:11

by looking at lung volumes,

2:12

we can see this patient did not take the greatest

2:15

inspiration, so their lung volumes are low.

2:18

The scalp can sometimes be a quick picture of that

2:21

as a pseudo chest X-ray showing not the greatest inflation

2:24

in low lung volumes, which together

2:26

with reticulation supports fibrotic

2:28

interstitial lung disease.

2:30

This patient did get referred to pulmonary medicine

2:34

for this interstitial lung abnormality found

2:36

on screening ct.

2:38

The challenge that we have during the interpretation

2:41

of lung cancer screening cts like this one,

2:44

is we get the history that says lung cancer screening,

2:47

and we make sure to have verification

2:50

of eligibility criteria like age

2:52

and pack years, often included in the order

2:55

for the examination.

2:57

What we don't often get is

2:58

Whether they have any pulmonary symptoms.

3:01

This finding of interstitial lung disease in a patient

3:05

with shortness of breath,

3:06

we can call interstitial lung disease.

3:09

If a patient has no symptoms

3:11

and they abnormal pulmonary function tests,

3:13

we call it interstitial lung abnormality, that's going

3:17

to be followed over time.

3:18

We just don't always have the information when reporting the

3:21

exams to say ILA versus ILD.

3:24

So sometimes what I'll put in my report is that there is

3:28

peripheral middle, lower lung predominant subpleural

3:31

reticulation with some subtle traction bronchiectasis

3:34

concerning for interstitial lung abnormality slash disease

3:38

and recommend referral to pulmonary medicine

3:40

with pulmonary function tests.

3:42

So this patient did go on

3:43

to see the pulmonary medicine physician

3:46

and they had an HRCT scan.

3:48

We can put the HRCT on the left that the patient underwent

3:52

because of the interstitial lung abnormality,

3:55

found the screening CT

3:56

and compare it to the lung cancer screening ct.

3:58

As far as the detail that we see, we would expect

4:02

that a low dose CT is done with as low a dose as achievable

4:07

to detect early lung cancer.

4:09

While an HR CT is going to be designed to

4:12

maximize the ability to see small reticulation,

4:15

ground glass traction, bronchiectasis,

4:17

and so on, to characterize and look for progression

4:20

or regression of interstitial lung disease.

4:24

On the lung screening ct,

4:25

everything looks a little bit softer.

4:27

Areas that look like clear reticulation back here in the

4:31

right lower lobe on the HRCT,

4:33

just look a little bit hazier and blurrier.

4:35

As tiny septa blur together to look like ground glass.

4:40

When it's really just reticulation, we can see

4:43

that the edges of the bronchi are sharper

4:45

and so on in the differences in technique.

4:47

So usually patients who have an ILA

4:50

or early fibrotic ILD suspected on screening CT will undergo

4:55

pulmonary function tests

4:56

and an HRCT commonly to confirm the findings,

4:59

particularly when it's mild, when it's much more extensive.

5:03

Honeycombing. That's very clear on the screening ct.

5:06

It's common to not repeat the examination as an HRCT.

5:10

So in this setting, the findings were confirmed on the HRCT,

5:14

the reticulation peripheral middle, lower lung predominance.

5:19

We can see them on the prone image as well

5:21

that they persist on the prone images.

5:24

It's not just dependent atelectasis masquerading

5:27

as interstitial lung disease

5:28

because this patient had no symptoms

5:31

and normal PTs, this patient will return

5:35

for their annual visit

5:36

with pulmonary function testing in one year.

5:39

Pulmonary medicine will be looking

5:40

for any decrease in pulmonary function

5:43

or any new symptoms to consider the use

5:46

of antifibrotic medications.

5:48

So this is an early detection, an early catch

5:51

of fibrotic ILD that we can do

5:53

with lung cancer screening exams

5:54

and we can set patients up

5:56

for early treatment when they should develop symptoms

5:59

or p fts become abnormality

6:00

and that time comes for antifibrotic medication.