Get a Group Membership for your Organization. Free Trial
Pricing
Free TrialLogin

Evaluation of Pulmonary Nodules and Lung Cancers with a Focus on Integrated Approach with CT and PET/CT, Dr. Lacey McIntosh (5/12/21)

HIDE
PrevNext

0:00

All right. Hello and welcome to Noon conference hosted by MRI online.

0:05

In response to the changes happening around the world right now and the

0:08

shutting down of in person events, we have decided to provide free noon

0:10

conferences to all radiologists worldwide. Today we're joined by Dr. Lacey

0:14

McIntosh. She is an assistant professor of radiology at UMass Medical School

0:17

and specializes in cancer and molecular imaging. She currently serves as

0:20

the director of oncology imaging at UMass Memorial Healthcare. She is teaching

0:24

and working with residents. Just a reminder that we will have time at

0:26

the end of the session for a Q&A part of that and you

0:30

can feel free to use the Q&A feature to ask your questions.

0:33

We'll get to as many as we can before our time is up.

0:35

That being said, thanks for joining us today, Dr. McIntosh. I'll let you

0:38

take it from here. Wonderful. Thank you for having me.

0:42

This is a great program. I've myself logged into a couple of

0:46

the Noon conferences to learn from some of these wonderful colleagues of

0:50

ours. I'm coming to you guys today from Massachusetts, but

0:55

I see from the participant list it looks like we have people from

0:59

all over the world here, which is really

1:01

a cool way to get the radiology or people interested in radiology community

1:05

together. Thank you for having me. Today I'm gonna talk about pulmonary

1:12

nodule characterization, diagnosis and staging. Really focusing on the pulmonary

1:17

nodules that end up becoming lung cancer. The two modalities we're really

1:23

gonna be talking about are CT and PET CT. I think it's important

1:27

that if you are looking at pulmonary nodules, either from

1:32

a general radiologist standpoint or if you're a dedicated

1:37

cardiothoracic or thoracic imager, or if you're more on the nuclear medicine

1:42

side where you're reading PET CT, it's really important to integrate the

1:46

imaging to come up with the best interpretation. You really can't read either

1:51

of these in isolation and you have to synthesize all the information that

1:56

you have together. We're gonna look at using the two modalities together

2:01

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

2:05

Disclosures, I work as a consultant for BioClinica, which does clinical

2:10

trial reads. And mostly for cancer drugs and novel tracers, but nothing

2:16

pertinent to this lecture. In terms of lung cancer imaging, we use CT

2:23

to really characterize size, morphology, look at local invasion of structures.

2:29

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

2:32

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

2:35

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

2:38

it's really hard to know, is this something that's been there forever and

2:41

it's unchanged or has this been slowly growing?

2:45

Is this something that wasn't there a week ago? Because that really changes

2:48

your differential. Behavior over time is a big one.

2:53

When you're using PET CT... Today I'm only speaking about 18 fluorodeoxyglucose

2:59

or FDG, which is basically a radioactive sugar molecule and is taken up

3:05

by any metabolizing cells. Obviously, we have normal tissues that are going

3:10

to have uptake like brain, sometimes myocardium, the GI tract.

3:15

We see it being excreted renally in the renal collecting system,

3:19

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

3:22

and cancers. While it's not specific for cancer, this is the primary tracer

3:27

right now that we use to look at the metabolic activity of certain

3:31

cancers. Depending on what your institution or your center does, the CT

3:39

portion can range from being a full contrast enhanced diagnostic CT to

3:46

really just a non contrast CT that's utilized for localization and has a

3:51

somewhat limited diagnostic value. I think that majority of cases,

4:00

these are being done with non contrast, so they're not a full diagnostic

4:05

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

4:08

view. The slices are often thick, five millimeters. And to avoid misregistration,

4:14

we usually take the CT with a tidal breathing technique. And so,

4:19

we don't ask the patient to take a breath and hold it.

4:22

We might take the CT portion as they're breathing or basically just ask

4:26

them to stop breathing. The reason for that is that we collect the

4:31

PET data over 20 to 30 to 40 minutes, and patient's obviously breathing

4:36

through all of that. If you have the patient take a deep breath

4:39

and do the CT portion, then you're gonna have a lot of misregistration.

4:42

And that's very important for pulmonary nodules, especially in the lower

4:46

lobes. PET CT provides functional information about the metabolic activity

4:51

of tissues. So, not only are you getting an idea of what your

4:55

nodule is doing, but sometimes more importantly, we're looking for evidence

4:59

of spread to the nodes regionally as well as distant metastatic disease.

5:06

As I mentioned, this isn't specific for cancer, but a positive PET doesn't

5:11

always equal cancer. There's false positives, infection, inflammation

5:16

being some of those. And then, a negative PET doesn't always equal no

5:21

cancer, so we can have false negatives as well. And one of the

5:25

areas that we really think about that are with slow growing lung cancers

5:30

and very small findings. Things that are larger are gonna be more FDG

5:34

avid. And the reason for that is they have more cells with GLUT1 transporters,

5:39

and so they're able to take up more tracer.

5:42

Small findings just don't have as many cells, and so

5:45

your accumulation is gonna be different. What you define as positive and

5:49

negative has to be taken into perspective about size of your finding.

5:55

One of the things that PET can be really useful for is

5:58

it can be helpful when your anatomic information is limited. If you have

6:03

an endobronchial lesion and you have post obstructive collapse, it can sometimes

6:07

be really hard to tell where your tumor is. And if you're trying

6:10

to figure out how to biopsy it or how suspicious it is,

6:13

PET can be really, really helpful. This is an example from the literature,

6:17

which is showing collapse of the right upper lobe. And you can actually

6:20

see this right upper lobe bronchus is basically cut off and it's filled

6:24

with something. Is it mucus and just post obstructive collapse from that,

6:28

or is it actually tumor? We see on the PET CT that this

6:32

is very FDG avid. It's right in the location we're expecting,

6:36

and so mucus is not gonna do this. This is a tumor with

6:39

post obstructive collapse. And so now we actually know the size of it,

6:42

which is important for T staging. We know the location, which is really

6:46

important for biopsy planning. It can give you a lot of information and

6:52

be very helpful when the anatomy is challenging.

6:55

Here's a case from our institution which is showing left lower lobe collapse.

Report

Faculty

Lacey McIntosh, MPH, DO

Director, Oncologic Imaging; Assistant Professor, Radiology

University of Massachusetts Medical School / Memorial Health Care

Tags

PET/CT FDG

PET

Oncologic Imaging

Nuclear Medicine

Chest

© 2024 MRI Online. All Rights Reserved.

Contact UsTerms of UsePrivacy Policy