0:02

Hello and welcome to Noon conferences

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hosted by MRI Online. In response to

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the changes happening around the world

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right now in the shutting down of in-person events,

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6 00:00:09,030 --> 00:00:10,740 we have decided to provide free daily Noon

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conferences to all radiologists worldwide.

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Today we're joined by Dr. Judy Yee.

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She's an accomplished radiologist

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and a pioneer in CT colonography.

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She is published extensively and a well-respected

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leader, researcher, educator, and mentor.

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She is past president of the Society of Abdominal

0:25

Radiology and a current leader in many organizations.

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That being said, thank you so much

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for joining us today, Dr. Yee.

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I will let you take it from here.

0:33

Okay, great.

0:34

Hello everyone and, uh, thank you to MRI Online,

0:38

um, for invitation to speak to you about one of

0:42

my favorite topics, which is CT colonography.

0:45

And the title of this talk is, uh,

0:47

Screening CT Colon: A Safe, Effective Test.

0:51

And, uh, during this, uh, talk, what I'd like to do

0:57

is, uh, start off by briefly reviewing with

1:00

you the epidemiology of colorectal cancer

1:02

and why it's so important, uh, to screen

1:05

for this mostly preventable malignancy.

1:08

Then we'll, uh, review some of the current

1:10

guidelines for colorectal cancer screening.

1:13

Um, I'll review with you state-of-the-art practice of

1:15

CTC, including, um, some of the validation studies,

1:20

and then we'll talk about current patient preparation

1:22

techniques, uh, and, uh, methods for interpretation.

1:27

And I'll end off with, uh, discussing briefly the

1:30

current status of reimbursement in the United States.

1:33

Um,

1:34

and

1:35

let's get started with, um, the

1:39

global, uh, colorectal cancer rates.

1:42

And it's important to note that

1:43

this is a common malignancy.

1:45

It's the third most common in men

1:48

and the second most common in

1:50

women globally.

1:51

So this accounts for 1.8 million new colorectal

1:55

cancer cases each year and about 880,000 deaths.

2:00

Look at where the highest rates

2:02

of colorectal cancer occur.

2:04

Well, in North America, that includes

2:07

both Canada and the United States.

2:09

Australia is a particularly

2:11

hotspot for colorectal cancer.

2:13

Uh, various sites in Europe,

2:15

uh, South Korea, and then Japan.

2:18

So here's a heat map of, uh, the, uh,

2:22

incidence rates for colorectal cancer.

2:25

And you can see that Australia has a very

2:27

high incidence rate, um, and is in red.

2:30

Everything else that's in orange is also fairly high.

2:33

So here states, but also various,

2:38

uh, large portions of, uh...

2:44

In the United States, uh, the statistics

2:47

really parallel globally, so it's the

2:49

third most common malignancy in the

2:51

second leading cause of cancer deaths.

2:54

Um, annually we have about 150,000 new

2:57

cases, about 50,000 deaths, um, and it

3:00

represents about 10% of all cancer cases.

3:04

And this, uh, again, shows you that in the States...

3:13

Uh, in men, uh, and in women.

3:15

So in men, it's behind prostate and

3:17

lung and women, it's behind prostate—

3:19

I mean, I'm sorry—breast and lung.

3:22

In terms of estimated deaths, you can see that, uh,

3:25

for men it's third, uh, behind lung and prostate.

3:29

And in women it's behind lung, breast.

3:31

However, when you consider, uh, men and

3:34

women together, colorectal cancer actually,

3:36

uh, accounts for and represents the

3:40

second most common cause of cancer deaths.

3:44

Again, the lifetime risk for developing

3:46

colorectal cancer is about 5%, uh,

3:49

which represents one in 20 individuals.

3:51

Lifetime risk for dying from

3:53

colorectal cancer is about 2.5%.

3:56

There is a slightly higher predominance in men.

4:00

I think this last line is particularly important,

4:02

which is that the majority—75%—occur in the average

4:06

risk patients who have no known risk factors.

4:10

So what are some of the risk factors

4:11

for developing colorectal cancer?

4:13

Some would say age itself, in that, um, anyone

4:17

over the age of 50 years, um, is considered at

4:20

increased risk, and 90% of colorectal cancers occur

4:23

in the over-50-year-old patient population.

4:28

There are certain known familial factors, so familial

4:31

adenomatous polyposis syndrome, Gardner syndrome,

4:35

a sub-cohort, the Ashkenazi Jewish, uh,

4:39

population—and all three of these are

4:42

thought related to the adenomatous polyposis

4:45

coli gene, which is located on chromosome 5.

4:49

Then we have the, uh, hereditary non-cancer.

4:59

African Americans are also known to have, uh,

5:02

increased, uh, risk for colorectal cancer.

5:06

Um, and then if you have a personal or a family

5:09

history—by that I mean a first-degree relative—

5:12

um, who has had a colorectal cancer or

5:15

polyps, that, uh, increases your risk. In women,

5:19

if you have had a history of ovarian,

5:21

endometrial, or breast cancer, this also, uh,

5:25

increases your risk. Then in patients with

5:28

inflammatory bowel disease of chronic nature,

5:31

so typically over 10 years of

5:33

duration, uh, this increases your risk.

5:36

And this is more common in

5:37

ulcerative colitis, um, and Crohn's.

5:41

And this, uh, pie chart just basically

5:44

demonstrates that there are known risk

5:46

factors, um, the hereditary types.

5:48

However, by far the largest piece of this

5:51

pie are the sporadic cases in patients who

5:54

are average risk, uh, with no known risk.

5:59

There are also some environmental

6:00

risk factors as well.

6:02

Um, and when you look at the list, it's, uh,

6:04

basically everything that's bad for you.

6:06

So, low-fiber, high-fat diet, um,

6:09

eating lots of red meat, inactivity,

6:12

having a high BMI, smoking, and alcohol.

6:18

Okay, let's talk about, um, the known

6:21

precursor lesion for colorectal cancer.

6:23

Um, and this is, uh, well known that most, uh,

6:26

colorectal cancers arise from adenoma polyps.

6:31

The risk of malignancy in an adenoma

6:34

polyp is correlated with polyp size.

6:37

So for a diminutive-sized polyp, which is

6:40

one to five millimeters, there's really a

6:42

0% chance that it actually will be malignant.

6:46

And, uh, these are the ones that the

6:49

American College of Radiology, uh,

6:51

recommends that you do not report. These—

6:53

that's what the DR stands for.

6:56

The small-sized polyps, six to nine millimeters,

6:59

uh, there's a less than 1% chance that,

7:02

uh, it actually, uh, is frankly malignant.

7:05

And then you can see why we consider

7:07

anything 10 millimeters or larger

7:09

to be clinically significant is that

7:11

the 10 to 20 millimeter size—there's

7:13

up to a 10% chance of malignancy.

7:16

Then over the size of 20 millimeters,

7:19

greater than 25% chance of malignancy.

7:23

Now, for a 10 millimeter and smaller polyp,

7:26

it generally takes about 10 years for it

7:29

to transition into invasive carcinoma.

7:32

So there's a very large window of opportunity

7:36

where we can go in, screen for this polyp,

7:39

if we find one, take it out, and, uh,

7:42

prevent the malignancy from occurring.

7:47

This is some of the, uh, validation studies showing

7:51

that, uh, the diminutive polyps one to five millimeters

7:55

in size really has, uh, harbors a 0% chance of malignancy,

8:00

but has less than a 2% chance of advanced histology.

8:05

For the small-sized polyps, six to nine

8:07

millimeters, uh, there's less than a 1%

8:09

chance that it's actually malignant, about 11%

8:12

chance that it has, uh, advanced histology.

8:17

Okay, let's, um, move on to, um—actually this

8:21

is a graphic that I developed to, uh, show you

8:23

the evolution of CT colonography over the years.

8:27

And CTC was first introduced, uh, at an SAR meeting

8:30

back in 1994, and then for a 10-year period

8:35

leading up to 2007, the major validation trials

8:39

were performed, both single and multicenter.

8:43

Animal models were evaluated.

8:45

We moved from single-detector to multi-detector CT.

8:49

We moved from room air insufflation to the

8:51

use of carbon dioxide insufflation, um, and

8:54

then, uh, improved hardware and software,

8:57

uh, for graphical display on workstations.

9:01

Many of you are aware that the ACRIN National

9:04

CT Colonography Trial was published in the

9:06

New England Journal of Medicine back in 2008

9:09

with excellent results, uh, showing, uh,

9:12

greater than 90% sensitivity of large polyps.

9:16

Uh, this led to the American Cancer

9:18

Society in the same year endorsing CTC

9:22

and joint guidelines, uh, for screening.

9:26

However, um, the U.S. Preventive Services Task

9:29

Force and then Medicare in 2008 and then in

9:32

2009 decided that there was insufficient evidence

9:36

to provide coverage for national screening.

9:40

So since then there's been continued, uh, work

9:43

performed, research published, looking at the

9:46

three main areas that Medicare has had

9:49

an issue with, which is radiation dose—which I

9:52

think is no longer currently a real issue—extra

9:55

colonic findings, and, uh, proper management

9:59

of those; the validation of Medicare-age patients.

10:03

Again, there have been multiple studies that have

10:05

evaluated this and showed that CTC performs well

10:08

in the age 65 and older, um, patient cohorts.

10:13

Um, on a positive note, since, uh, 2009, uh, we have

10:17

noted, particularly in the States, that insurance

10:20

companies, private payers, have continued to

10:23

increase coverage, uh, not only for diagnostic

10:26

CT colonography, but for screening as well.

10:29

Um, and since 2009, we've seen

10:31

significant, um, dissemination of CT

10:34

colonography really throughout the world.

10:37

In 2013, the FDA in the U.S., um, held a special

10:43

joint panel, uh, that ended up supporting

10:46

screening CT colonography and said that

10:48

it was both a safe and an accurate exam.

10:52

The U.S. Preventive Services Task Force was

10:54

back in, uh, 2008, uh, had not approved

10:58

CTC. In 2016, uh, they decided to include CT colonography

11:03

as a valid option for colorectal cancer screening.

11:06

So that was more good news.

11:08

However, in 2017, when, um, CT colonography went

11:13

back to Medicare, uh, they decided that they

11:16

would deny national coverage determination.

11:20

Then the American Cancer Society again decided

11:22

to endorse and support CT colonography in 2018

11:27

as a valid option for colorectal cancer screening.

11:30

That pretty much brings us up to the present.

11:33

So this is just from the USPSTF,

11:36

um, 2016 decision where they basically said that, um,

11:43

the best screening test is the one that gets done.

11:45

Um, and they included CT colonography in the

11:49

same category as direct visualization tests, as

11:53

colonoscopy, um, as a valid test, uh, every

11:56

five years, uh, for colorectal cancer screening.

12:01

This is from the 2018 American

12:04

Cancer Society guideline.

12:06

Uh, and, uh, at this time it was landmark because

12:11

they actually decreased, uh, the recommended start

12:14

of screening from age 50 years, uh, to age 45 years.

12:18

And...

12:23

But you can see that they have divided, uh, colorectal

12:25

cancer screening tests into stool-based tests, which

12:28

included a fecal immunochemical test annually,

12:32

so every year, the guaiac-based fecal occult blood

12:35

test, the FOBT annually, the multitarget stool

12:39

DNA test every three years. On the structural exams,

12:43

which—and these are the direct visualization exams—

12:46

they have colonoscopy every 10 years, CTC every

12:50

five years, and then flexible sigmoidoscopy every five years.

12:55

And I did want to touch upon, uh, this, uh,

12:59

issue of early-age onset colorectal cancer.

13:03

And this is what led the American Cancer

13:05

Society to, uh, decrease the age for start of...

13:12

And what's been noted as a trend, as you can see

13:14

that I have indicated here, is that early-age onset

13:18

colorectal cancer has really, um, been noted, uh,

13:22

starting, uh, since the mid-1980s when there was an increase by up to about

13:26

2.5% annually, um, in the, uh,

13:30

colorectal cancer cases in the 20 to 39-year-old cohort.

13:38

Then an increase by up to 1.3% since the mid

13:42

1990s in the 40 to 54-year-old patients.

13:46

Then finally, rectal carcinoma in particular is

13:50

of concern, 'cause it's increased faster than the

13:53

rest of the group by 3.2% annually, up to 2013.

13:59

You can see in 2020...

14:03

This is globally. This is not

14:04

just in the United States.

14:07

So what was found was that compared with

14:10

adults born in 1950, those born in 1990

14:14

have doubled the risk of colon cancer and

14:17

quadrupled the risk of developing rectal cancer.

14:22

Now, why has there been, uh, this increase in

14:25

early-age onset, uh, colorectal cancer cases?

14:29

And it's, uh, not entirely known at this point.

14:32

Um, what has been noted is that greater than 75% of

14:35

these cases are in, uh, individuals who do not have

14:40

a family history of colon cancer

14:42

and who do not have a genetic syndrome.

14:44

So there's definitely something else going

14:46

on, and it's queried as to whether this

14:49

might be related to a change in the gut

14:51

microbiome that has happened over the years.

14:54

Um, this is paralleled by an increase in rates

14:57

of obesity and diabetes in young adults.

15:00

So perhaps those are, um, enhancing

15:03

factors for, uh, this increase.

15:06

We know that, uh, younger individuals

15:09

have decreased, uh, milk consumption.

15:12

Um, at the same time, we know that, uh, calcium

15:14

actually, uh, has somewhat of a protective effect.

15:17

So with, uh, less milk consumption,

15:20

maybe there's a decreased protective

15:22

effect of, um, having calcium around.

15:25

Then of course, you have to throw out environmental

15:27

toxins, and this would have to be a widespread

15:31

toxin since this, uh, is occurring, as I

15:34

mentioned, in, um, many countries around the world.

15:40

Okay, so the American College of Radiology

15:43

has also included CT colonography

15:45

in the appropriateness, uh, criteria.

15:48

302 00:15:48,660 --> 00:15:51,450 And you can see that, uh, currently CTC, uh,

15:51

rank the highest and is usually appropriate,

15:54

uh, whereas the double contrast barium enema is, uh, lower rated as

16:00

may be appropriate, along with MR colonography.

16:03

And single contrast BE is usually not appropriate.

16:08

There are joint, um, multi-society practice

16:12

parameters that have been published for CTC as well.

16:15

Um, and these are the indications,

16:17

uh, that, uh, that are included.

16:21

So as a screening test in average-risk asymptomatic

16:24

individuals, as a surveillance test in patients who

16:28

are asymptomatic but who may have, uh, risk factors,

16:32

uh, and are at increased risk; as a diagnostic

16:35

exam in patients who are currently symptomatic.

16:38

And you can see the symptoms that I have listed,

16:41

uh, following a failed or incomplete colonoscopy.

16:44

So the gastroenterologists were not able

16:46

to get the scope all the way to the cecum.

16:49

Um, patients who are high risk for undergoing

16:51

colonoscopy, so they may be at risk, um, for

16:55

having sedation, or they may be on anticoagulation

16:58

therapy, for example; post-colectomy,

17:02

and then, uh, for pre-surgical planning, uh,

17:05

prior to, um, surgery for colorectal cancer.

17:11

These are the, uh, qualifications, uh,

17:14

that you need, uh, as recommended by this

17:17

multi-society practice parameter, uh,

17:20

for, uh, being able to interpret, uh, CTC.

17:24

Um, if you have performed a radiology, uh,

17:28

residency, you qualify under the category

17:31

of physicians already with prior CT

17:34

interpretation supervision qualifications.

17:38

And so all that you need then is

17:40

specific training in CTC technique.

17:42

Um, and this is, uh, achievable

17:46

through, uh, typically courses that

17:48

are available, um, interactive review.

17:52

So this is hands-on, uh,

17:54

training of at least cases and—

17:58

tagging and with/without IV contrast.

18:01

And I know that in different countries, the

18:03

number of cases may, uh, be higher—at 75 cases,

18:07

and then some require actually double—50 and

18:09

100 cases for maintenance of competence.

18:12

What's recommended, uh, by the ACR and some of

18:14

the other U.S. societies is at least, uh, an

18:18

additional 50 cases over the course of two years.

18:23

And this was an interesting study that was published,

18:26

uh, last year, um, entitled *CT Colonography:

18:29

How Many and How Fast Radiologists Report.*

18:31

You can see that they looked at over 5,000 CTCs

18:35

interpreted by seven radiologists, um, and they

18:38

evaluated referral rates and polyp detection rates.

18:42

What they found is that both the referral rate and the

18:45

polyp detection rate actually decreased by 7% for each

18:50

successive CT colonography case that you interpreted.

18:54

And then radiologists who reported more slowly,

18:58

uh, actually detected more polyps, uh, with each

19:01

60% increase in interpretation time associated with

19:04

a 1% increase in your polyp detection rate.

19:08

So their conclusion was that you

19:10

shouldn't read too many of these,

19:13

um,

19:13

so no more than four at one sitting. You should

19:17

take a break, and you shouldn't read these too fast.

19:20

So you should use, um, over

19:22

20 minutes, uh, for each case.

19:27

Okay, let's move on to practice of CT colonography.

19:30

And I'm just gonna put out there some of the advantages

19:32

of CTC, which I think are pretty straightforward.

19:36

It is considered a minimally invasive exam.

19:38

And so this translates typically

19:40

to better patient tolerance.

19:42

It's a very short procedural time, and we

19:44

know that sometimes it takes more time to

19:47

get the patient, um, on the table and

19:49

positioned and insufflated than it is for—

19:52

the actual scanning time is very short.

19:54

At, uh, typically, uh, less than

19:56

15 seconds, uh, in each position.

19:59

There's no need for sedation.

20:00

So, uh, you don't need, uh,

20:02

anyone to accompany the patient.

20:04

And we'll see that this actually is a real advantage,

20:07

uh, during, uh, the pandemic.

20:10

Uh, it's considered a safe exam, so very low risk

20:13

for perforation—10 to 20 times lower than the

20:17

perforation rate for, uh, colonoscopy, for example.

20:21

It can be less costly.

20:23

Um, and even though, uh, screening CTC is

20:26

not reimbursable, uh, by Medicare, um, it is—

20:31

when it is reimbursed by private payers, the

20:33

cost is actually less than for colonoscopy.

20:36

And you have the ability for opportunistic

20:38

evaluation of other diseases.

20:40

So for example, inherently you can look for

20:43

abdominal aneurysm, um, and steatosis of the

20:48

liver, uh, and for bone mineral density.

20:52

What are some of the limitations of CTC?

20:55

Well, as we all know, currently

20:57

still requires bowel cleansing.

20:58

There have been several large studies that have

21:01

looked at, uh, decreasing the, uh, prep for CTC, and

21:05

I think that, uh, additional work is still ongoing.

21:08

So we have not come to a point where we

21:11

can say that you don't need a prep for CTC.

21:15

It does use, uh, radiation, although

21:17

we have significantly lowered the dose.

21:19

And I don't think that that

21:20

is a real issue at this point.

21:24

Uh, for, um, the USPSTF, um, extra

21:27

colonic findings, the incidence, uh, and,

21:30

and you know, we always look at, uh...

21:32

You know, there are lots of extra colonic

21:35

findings that occur, but when you look—and I

21:37

think the key is really, um, looking at the

21:40

rate of colorectal extra findings that

21:44

uh,

21:44

will actually change management and

21:47

that, uh, actually have impact on the patient.

21:50

Uh, and

21:50

those, um,

21:52

uh,

21:52

wind up, uh, triggering very few additional exams.

21:56

Uh, so, you know, I think that, uh, there's a lot—

21:58

there are a lot of studies that have been published

22:00

looking at this, and, uh, it should not be an issue

22:03

again

22:03

for, uh, the major, um, societies.

22:07

Um, patients are required to undergo

22:09

colonoscopy if there is a positive finding.

22:12

Um, and I would say that, uh, um, this—if

22:16

it's not done on the same day—this means the

22:18

patient has to repeat the, um, bowel cleansing.

22:22

Um, and then there is additional cost.

22:24

So, um, but that can be said for

22:27

any other, I think, colorectal cancer

22:28

screening test outside of colonoscopy.

22:31

So it's not just a limitation for CTC,

22:34

it really is for all the other screening

22:36

tests, like, um, fecal immunochemical tests

22:39

and for stool DNA testing, for example.

22:42

Okay.

22:43

Let's look at some of the validation studies,

22:45

and I'll go through these pretty quickly

22:46

because I think you may be familiar with these.

22:48

Uh, this was the large, uh, ACRIN trial, uh, published

22:53

in the New England Journal of Medicine back in—

22:55

It was a multi-site trial.

22:59

See 15 sites, uh, including over

23:01

2,500 asymptomatic adult patients.

23:05

Uh, used state-of-the-art technique with stool

23:09

tagging, um, reader certification was performed.

23:12

So in order to qualify to be a reader, you had to

23:15

pass the test and achieve an accuracy of over 90%.

23:20

Um, and you can see the results were excellent.

23:23

Uh, there is, uh, increasing, uh,

23:25

sensitivity with increasing polyp size.

23:28

So when we get to the clinically significant

23:30

size of 10 millimeters and above,

23:33

you can see a 90%, uh, sensitivity.

23:36

Now, when you look at six millimeters and

23:38

above, we're at about 78% sensitivity.

23:41

Specificity throughout all categories was in the—

23:47

These are additional, uh,

23:48

studies, um, performed in Europe.

23:50

The Munich study.

23:52

You can see that, uh, these were also asymptomatic,

23:55

average-risk patients. Per polyp sensitivity,

23:58

the six millimeter and larger and the nine

24:01

millimeter and larger were in the, uh, low

24:03

90th percentile. Per patient sensitivity,

24:07

again, 91%, 92%, with high specificity.

24:11

And again, in the Italian study—the IMPACT study—

24:14

uh, really the results, uh, parallel, I think, the

24:17

ACRIN trial. You can see for nine millimeter and

24:20

10 millimeter polyps at over 90%, uh, sensitivity.

24:26

And then, um, specificity, uh, also parallels

24:29

pretty much what we saw in the trial in the

24:32

high eighties and then at 90% with the six.

24:37

And then this is a recent meta-analysis that

24:40

looked at 14 studies—over 3,500 patients.

24:43

And again, you can see excellent sensitivity.

24:48

91% specificity of 98%.

24:52

So perhaps with these later studies,

24:54

tagging specificity, um, has increased.

24:58

And then for the six millimeter,

25:00

87%, uh, sensitivity, 90.

25:05

What about, uh, current, uh,

25:08

technique for bowel cleansing?

25:10

Um, many sites have moved from the large

25:14

volume polyethylene glycol, um, prep,

25:17

which is a wet prep, to the dry prep.

25:20

And whereas initially, uh, sites were using

25:24

sodium phosphate or Phospho-soda, I think

25:26

that many sites have moved towards magnesium

25:29

citrate and mag citrate, um, is smaller volume.

25:33

So you have the patient typically ingest 10 ounces.

25:36

Um, this can be given as a

25:38

single dose or, um, given twice.

25:41

Um.

25:42

Magnesium citrate is hyperosmolar, so it draws fluid

25:45

into the bowel lumen, uh, which induces evacuation.

25:49

It tends to be better, uh, tolerated by

25:52

patients, uh, and also leaves less residual fluid,

25:56

um, which makes it easier, uh, for interpretation and

25:58

allows actually for typically better, uh, tagging.

26:03

So, uh, 10 ounces of magnesium citrate given

26:06

as either a single dose, uh, or in two doses.

26:09

Uh, or some sites still use, uh, Phospho-soda.

26:12

And this should be a single dose of 45 mL.

26:15

Remember that Phospho-soda specifically

26:18

is contraindicated in patients with renal

26:21

insufficiency or patients with, uh, cardiac failure.

26:26

As I mentioned before, the wet

26:27

prep is the polyethylene glycol.

26:30

Uh, this is typically given

26:31

as a larger volume—four liters.

26:34

It is an iso-osmolar lavage solution,

26:37

um, because it is such a large volume.

26:40

Uh, compliance, uh, may be an issue for

26:43

patients, and it tends to leave much more

26:45

residual fluid in the colon lumen, uh, which

26:49

can, uh, be problematic for interpretation

26:52

and lead to less, uh, homogeneous, uh, tagging.

26:57

There is an option for two liters of polyethylene glycol.

27:00

For some reason, this tends

27:01

to be a more expensive option.

27:03

Um, and there, uh, are studies showing that the four

27:06

liter volume is no better than the two-liter volume.

27:10

This is the ACRIN, uh, tagging protocol.

27:13

Uh, patients typically have to go on a

27:16

clear liquid diet the day before the CTC.

27:19

Um, the, um, tagging is achieved with, uh,

27:23

both a high-density barium product, uh, that

27:27

is, uh, given in three aliquots at 8:00 AM,

27:30

11:00 AM, and at 2:00 PM, um, with the largest

27:34

volume at the 8:00 AM—20 mL in PM.

27:40

Now there's a certain order

27:41

that this needs to be given.

27:43

And so this, uh, higher-density barium product,

27:47

oral barium, uh, is meant to tag any solid stool

27:51

that's in the colon. In the late afternoon,

27:55

the patient receives the laxative.

27:57

This can either be magnesium

27:59

citrate, um, or polyethylene glycol.

28:03

Um, and then this evacuates all of the

28:05

solid stool, or it's meant to evacuate

28:07

as much of the solid stool as possible.

28:10

7:00 PM bisacodyl tablets, uh, are given as an

28:14

adjunct, uh, for additional cleansing.

28:17

And then in the evening, um, water-soluble contrast

28:21

is given—Gastrografin—uh, starting at

28:25

9:00 PM, uh, again in three aliquots of 20 mL each.

28:30

Uh, and, uh, the iodinated contrast

28:33

is meant to tag any residual fluid.

28:36

So the high-density barium product in the

28:39

morning and early afternoon to tag solid

28:42

stool, and then the laxative in the late

28:45

afternoon to evacuate most of the solid stool.

28:48

Um, and then the iodinated

28:50

contrast in the evening, uh, to detect residual fluid.

28:54

This has worked quite well.

28:56

This is a, uh, alternative tagging protocol

28:59

from the University of Wisconsin, um, where

29:02

they use, uh, two doses of magnesium citrate.

29:05

Some sites have found that the one bottle

29:08

of magnesium citrate doesn't cleanse

29:10

patients—some patients—well enough.

29:13

Um, and this is, uh, using two, two bottles.

29:17

So, uh, again, um, a clear

29:20

liquid diet on the day before.

29:22

Um, bisacodyl tablets are given at

29:24

11:00 AM. The first bottle of magnesium

29:26

citrate is given in the late afternoon.

29:28

Um, and then in the early evening,

29:31

the second bottle of magnesium citrate is

29:33

given, and then a larger volume of, uh, lower

29:37

density barium products can be given after that.

29:41

Um, and then the iodinated contrast is given

29:44

similar to the protocol starting at—

29:49

I think that irrespective of whichever, um,

29:53

protocol you use, it's important to have a clear prep

29:56

sheet, uh, to hand out to patients or to send to them.

30:00

Um, graphics are appreciated by patients,

30:04

we have found, and, uh, you're very

30:06

welcome to, uh, use the one that I have shown here.

30:10

Um, but it really goes through step-by-

30:11

step, uh, what the patient needs to, uh,

30:14

ingest and how they, um, mix things up.

30:18

So I think that, uh, this has, uh,

30:19

been very helpful for patients.

30:23

Now, for colonic distension, we had switched

30:26

to, um, using carbon dioxide, um, many, many

30:30

years ago—over, I would say, 10 years ago.

30:33

Uh, and have had great success,

30:35

uh, using an electronic method.

30:38

This is, uh, displayed here.

30:40

Why use carbon dioxide is because it has high liquid

30:43

solubility and high partial pressure gradient.

30:46

Uh, so what that means is that there's

30:49

actual resorption of CO₂ across the mucosa,

30:54

and after the exam is over, um,

30:58

there's resorption, uh, of the CO₂, making

31:01

the exam much more comfortable for patients.

31:04

And this has been, um, demonstrated in, uh, trials.

31:08

Um, so what I have demonstrated

31:10

here is the mechanical device.

31:12

Uh, this is a consumable tubing

31:15

that's used.

31:16

Uh, there's a balloon at the end that can be inflated.

31:19

This is a fluid catch, uh, particularly important if

31:22

you're performing tagging, uh, which is recommended.

31:25

Uh, and then a one-way filter.

31:27

And, uh, this is the end of the tip that

31:30

goes into the, uh, electronic insufflator.

31:33

And it senses, uh, pressure in the, uh, rectal bulb.

31:39

For image acquisition,

31:41

according to guidelines, what's recommended

31:43

is at least a 16-slice multidetector

31:45

CT. For your tube settings, either 25 up

31:49

to 50 mAs, or you can use auto mA kVp.

31:53

Most sites use the 120 kVp. Um, for a lower dose,

31:58

you can, and it has been shown to be effective

32:01

in published trials. You can decrease to a

32:04

100 kVp. Slice thickness of 1.25 millimeters.

32:09

Um, what's required is scanning in two opposing

32:12

positions, and typically this is in the supine and

32:15

prone acquisitions. Patients with a large BMI perform

32:21

right and left lateral decubitus as an option.

32:25

After performing supine and prone acquisitions,

32:28

if you do not have sufficient insufflation

32:32

or adequate cleansing in a particular

32:35

area, you can perform focused, limited decubitus view

32:38

of the particular segment.

32:41

Typically, this will be in the sigmoid area.

32:45

Remember to acquire your scans in end-expiration.

32:49

Um, why?

32:50

Because this will allow for the diaphragms to move

32:53

up, and it increases the body cavity size, so you

32:56

have more adequate, um, distension of the colon.

33:02

What about radiation?

33:03

And just to put this in perspective, um,

33:07

you can see that the average annual natural

33:09

background dose that you and I receive just

33:11

walking on this Earth is about 3 millisieverts.

33:15

If you live in an area at a higher altitude,

33:19

the average background dose is about 12 millisieverts.

33:22

Uh, and so you do get higher dose, uh,

33:24

when you live at a higher altitude.

33:27

For CT colonography, we have actually achieved

33:29

very low dose, and you can see that, um, what I have

33:32

listed here is pulled right off of our CT scanner,

33:36

and the dose-length product, um, for including

33:39

supine and prone series is at about 200

33:44

milligray∙centimeters (mGy·cm).

33:47

When you multiply it by the conversion

33:49

factor for estimated dose, this is an

33:51

equivalent of about 3 millisieverts.

33:54

So using this type of a protocol that I delineated to

33:59

you on the prior slide, we can achieve a very low dose

34:03

that's equivalent to the annual background dose.

34:06

Um, the Health Physics Society has

34:09

put out this statement, which is:

34:10

Below 50 to 100 millisieverts, the

34:13

risk of health effects is either too small

34:15

to be observed or actually non-existent.

34:18

And so we are orders of magnitude below that.

34:21

And so, um, there's no clear risk.

34:24

This was a study, uh, performed looking

34:26

at the benefit–risk ratio.

34:31

And so they looked at the estimated, um,

34:33

colorectal cancers that are prevented from

34:36

performing screening CTC every five years versus

34:40

the estimated radiation-induced cancers from

34:43

performing screening CTC every five years.

34:47

And they found that there was a very high benefit,

34:50

um, to risk ratio at 24 to 35 to one.

34:55

So it meant that there was clear higher benefit,

34:58

um, in detecting many more cancers that

35:01

could be prevented, uh, than actually causing, uh,

35:05

radiation-induced cancers from the CTC.

35:10

This is what we want to see: a

35:12

well-distended colon.

35:15

Uh, for the CTC on the scouts, you

35:17

should train your technologist to look for this.

35:20

In particular, you want to make sure that your rectal

35:22

sigmoid is well-distended because most

35:26

colorectal cancers occur in the rectal sigmoid.

35:28

So again, make sure that your technologists

35:32

are trained to, in particular,

35:37

assure they can have adequate distension

35:39

in this area. There are two methods for

35:43

interpretation: primary and 2D interpretation.

35:45

And this is what's demonstrated here.

35:47

We have a large display—your

35:49

axial, supine, and prone images.

35:52

Um, and, uh, you would scroll from the

35:56

rectum all the way using colon tracking.

36:01

Um, if you find something suspicious on the

36:04

2D views, you'll put an arrow or, um, some,

36:09

uh, indication that you found something.

36:11

This arrow should then translate

36:13

automatically, uh, to the 3D views.

36:15

And you can see in this particular

36:17

platform, have a sub–subvolume queue.

36:20

Uh, and, uh, there's a nice, uh, donated

36:23

polyp that's demonstrated on the prone view.

36:26

Uh, this particular software also allows

36:29

you to automatically measure the, uh,

36:32

volume of the lesion, the maximum diameter,

36:35

and then the distance from the rectum.

36:38

And all of these can be easily, uh,

36:40

imported into a, uh, radiology report.

36:45

Here's another patient.

36:46

And you can see on the supine there's a

36:49

homogeneous soft tissue, uh, spherical-type

36:52

lesion, uh, located along the posterior

36:55

wall of the segments of the sigmoid.

36:57

Uh, in the opposing view, uh, we

36:59

have found a similar appearance,

37:01

um,

37:02

for this lesion.

37:03

Uh, and this was a nice demonstration of a large,

37:06

sessile polyp that you can see also on

37:10

the, um, subvolume cube view, uh, right below.

37:17

And again, uh, this software easily allows

37:20

you to measure maximum volume, the diameter,

37:24

and then the distance, uh, from the rectum.

37:29

There's primary 3D interpretation where

37:31

you basically use your fly-through

37:33

as your primary view to find lesions.

37:37

Um, and here we have found, uh,

37:41

immediately a very large donated polyp.

37:45

Um, you can put a cursor on it or an arrow.

37:47

It automatically translates into your 2D views.

37:51

Uh, and you can see this on both

37:52

the sagittal, here's the coronal.

37:55

Here's the axial.

37:57

Um, and again, uh, software allows you to

38:01

easily measure this, uh, automatically.

38:05

Here's a different platform, uh, that has

38:07

the filet or the dissection view on top.

38:11

This patient has a large, uh, sigmoid carcinoma,

38:15

uh, with several large polyps as well.

38:18

Um, you can see that there is some distortion of

38:21

the lesions on the, um, flat dissection view.

38:27

Okay, let's look at the typical appearances of polyps.

38:31

The classic teaching is that, uh, stool,

38:35

um, residual stool has angulated or

38:37

branched appearance on the 2D views.

38:41

Um, and, uh, is heterogeneous in

38:44

appearance, typically containing some air.

38:46

While polyps typically have a

38:48

homogeneous, ovoid, or rounded appearance.

38:52

Um, and, uh, you can see the

38:55

3D view here as well.

38:58

Again, for the five millimeter and smaller

39:00

lesions, which are considered diminutive,

39:04

you do not need to report these, so don't spend

39:06

a whole lot of time trying to problem-solve

39:09

these little, uh, very little lesions.

39:12

Um, the six to nine millimeter

39:14

lesions are considered small.

39:15

You have to report these.

39:17

And then 10 millimeter and above

39:19

are considered large lesions.

39:21

Here again is a very nice

39:22

demonstration of a large donated polyp.

39:26

Uh, you can see on the 2D view that

39:28

there is a coating of contrast.

39:30

Um, when you measure these lesions here,

39:33

normally I would recommend that you measure on

39:34

3D, but when you have a coating of contrast,

39:37

I would go to the 2D actually to measure,

39:40

because I want to exclude that contrast cap.

39:45

Here's a case that was very interesting,

39:47

where on the 2D view on top, it's very hard to

39:50

tell what's going on, and, uh, you can see that

39:53

there's a soft tissue density, um, with head

39:56

here and then there's something coming off here.

39:59

I think that...

40:02

It's showing that actually two large polyps.

40:09

So here's polyp one, the head,

40:14

and then we turn your, your, uh, perspective.

40:17

And here's the long axis of polyp number two, uh,

40:20

with the head hiding right behind this fold.

40:24

Um, and here's my demonstration of both.

40:26

Polyps, again, can—you can have very irregular

40:29

morphology to polyps, uh, just to note.

40:33

And, uh, this angular shape, as I mentioned

40:36

before, is typically seen with stool.

40:38

But in this particular case, um, you want to use

40:41

your 2D views, and it shows that it was homogeneous

40:43

soft tissue and then clearly a true polyp.

40:46

And then here's another lobulated polyp.

40:49

Again, when you see things like this on 3D, if

40:51

you're a primary 3D, uh, reader, you have to use

40:54

your 2Ds, uh, to look at the soft tissue density.

40:57

Here's a, um, club-shaped, uh, polyp.

41:00

Again, you go to your 2D view.

41:02

Uh, soft tissue density, clearly a...

41:11

Um, we will always have to use the maximum

41:14

diameter of, uh, polyps, uh, in the report.

41:18

Why is because your gastroenterologist

41:21

cannot tell the volume, um, when they're

41:24

performing the colonoscopy, and they always

41:26

wanna correlate with the maximum diameter.

41:29

So it's not irrespective of whether

41:31

it's the length or the width.

41:32

You really need to look at both, uh, on

41:35

the 3D view and measure just the largest,

41:37

uh, diameter—whatever direction that's in.

41:40

And just, this is just—that was

41:42

from a question that I just thought.

41:43

This is a, uh, disco-type, irregular-shaped polyp.

41:47

And you can see the morphology is, um, very

41:51

irregular, both on the, uh, 3D and the 2D.

41:55

What about this case, where on the 2D you do see

41:58

this sort of angular shape, but when you look at

42:01

it on the 3D, you see that there is a short stalk.

42:05

And, uh, all that this represented was an

42:09

inflated rectal balloon that's flattening

42:12

this, uh, undulated polyp, and that's causing

42:15

uh, the angulated appearance on the 2D.

42:20

And what about this case?

42:21

Uh, where on the top row we see that, uh,

42:25

the, uh, rectal balloon has been inflated.

42:28

Um, and when you deflate it, you can see what pops up.

42:32

Is this, uh, true polyp?

42:35

So the recommendation is that in at least one

42:38

position you should deflate the rectal balloon.

42:42

Um, if you are actually using, uh, an

42:45

inflated rectal balloon. At my site, we don't

42:47

actually typically inflate the balloon.

42:50

Um, and we're able to actually still

42:52

achieve, um, adequate distension.

42:58

Flat lesions are tough.

43:01

Uh, I think for the radiologist, um, I...

43:04

You do need to use soft tissue windows.

43:07

When you look at the colon window here, um, it's

43:09

really hard, I think, to identify a lesion.

43:12

But when you look at this on the soft tissue

43:14

windows, um, you can clearly see that there's

43:18

more focal, lobulated, irregular soft tissue.

43:20

And, uh, this turned out to be, um, a serrated lesion.

43:25

Here's another example of just irregular, focal, uh,

43:29

soft tissue along the anterior wall on the supine and

43:31

the prone, along the anterior wall.

43:34

Um, again, this was a true lesion and

43:36

you can see it also on the 3D view.

43:39

Now I'm gonna tell you a trick, which is that, uh,

43:42

tagging, um, often can help you to find these lesions.

43:46

Why? It's because the majority of these

43:48

lesions will have a contrast coat that

43:52

highlights the lesion for us to find.

43:54

So in particular here, you can see this

43:56

lesion has, um, a coat of contrast on its

44:00

surface, uh, and you're able to spot it

44:03

and, uh, correlate it with the 3D view.

44:05

I think it's harder to see on the 3D view

44:07

than on the, um, optical colonoscopy view.

44:10

Here.

44:11

It's again, the opposing view.

44:13

I think the contrast coating nicely

44:15

highlights, uh, this flat lesion, and

44:19

here again, on the supine and prone.

44:21

And then on the coronal view, um, the contrast

44:25

really draws your eye, uh, to the lesion.

44:29

And this was a study, uh, published

44:31

by David Kim looking at flat polyps.

44:34

Um, 80% of them

44:36

showed a, uh, coat of contrast.

44:39

These tended to be, uh, on the large side, so,

44:42

uh, a little over nine millimeters in size.

44:46

There were three factors that they found that

44:48

were associated with this contrast coating:

44:51

the large size—10 millimeters and above—if it was

44:54

located in the right colon, so a proximal location,

44:58

and then, um, if it was a serrated, uh,

45:01

histology. And we'll talk more about this.

45:04

I dunno how many of you know this, but

45:06

there are actually different pathways, uh,

45:08

for the development of colorectal cancer.

45:11

I think all of us are familiar with the adenoma–

45:13

carcinoma sequence to developing colorectal

45:16

cancer, where you go from a normal colon to

45:19

a small adenoma and then to a larger one,

45:23

and then, uh, um, evolution to colorectal cancer.

45:27

You have the non-polypoid pathway to colon cancer.

45:30

And typically this occurs in

45:32

patients with inflammatory...

45:35

Uh, like ulcerative colitis and Crohn’s disease.

45:38

And then there's this third serrated pathway

45:40

to colon cancer. And hyperplastic polyps,

45:43

which are, uh, benign, are in this pathway.

45:46

Um, so hyperplastic polyps themselves are

45:49

benign, but they are, uh, in the pathway for

45:51

the development of the sessile serrated polyp,

45:54

which then can evolve into colorectal cancer.

45:58

And it's thought that up to about 20%

46:00

of colorectal cancers actually develop

46:02

from this serrated polyp, uh, pathway.

46:07

So the World Health Organization has, um,

46:10

classified serrated polyps into three types.

46:14

We have a hyperplastic polyp, as I mentioned, and

46:16

these represent the majority—70% of serrated polyps.

46:20

The sessile serrated polyp or sessile serrated adenoma

46:24

represents 25% of, uh, serrated polyps.

46:28

And then you have the traditional

46:30

serrated adenoma, the TSA,

46:32

which is the minority—only 5% of serrated polyps.

46:36

Now the good news is that the sessile

46:39

serrated polyp and the traditional serrated

46:41

adenoma both, um, exude this mucin cap.

46:46

And it's thought that it's the

46:47

electrostatic properties between this

46:50

mucin cap and the, uh, tagging product,

46:55

so the barium product in particular,

46:57

that causes, uh, this contrast cap.

47:01

Um, I don't think that it has, uh, actually, um,

47:04

absolutely been proven that it's the barium that,

47:07

that, uh, and only the barium that causes the cap.

47:11

Um, but that, um, iodinated contrast potentially,

47:14

um, may be involved in this cap as well.

47:17

It's just not known currently.

47:19

So this is a summary chart just to go over with you

47:23

that, um, adenomas can have various morphologies.

47:27

Um, they are relatively common,

47:31

common in the right colon than the left,

47:34

uh, and they are, uh, pre-malignant.

47:37

Um, the sessile serrated polyp and the traditional

47:40

serrated adenoma are also pre-malignant.

47:43

The sessile serrated polyp tends to be flat in

47:46

morphology, uh, larger. They're, uh, more

47:49

common, uh, than the traditional serrated adenoma,

47:52

and they tend to be in the right colon.

47:55

In contrast, the traditional serrated

47:57

adenoma can be smaller or large, um, and when

48:01

they're smaller, they tend to be sessile.

48:04

As I mentioned,

48:05

they're uncommon, um, and they tend to occur

48:07

in the left colon, so in the distal colon.

48:10

They also can be irregular in morphology.

48:13

When they are, they tend to be larger.

48:15

So I'm gonna show you a, a study

48:17

that was just published looking at

48:19

these TSAs, uh, on CT colonography.

48:23

Um, and this is international experience.

48:26

Um, and you can see that, um, over

48:28

65% were located in the left colon,

48:31

with a, uh, mean size of

48:35

uh, almost 20 millimeters.

48:37

Again, when they were larger, they

48:38

tended to be irregular or lobulated,

48:41

even "carpet-like," uh, in morphology.

48:44

And of note—and good for us—is that almost

48:47

90% of them actually have contrast coating.

48:54

Artificial intelligence algorithms have been

48:57

developed trying to find these serrated polyps,

49:00

and they've been developed in particular to look

49:02

for this contrast coating, 'cause there's high

49:05

association of the coating with these polyps.

49:08

You can see that in this one study that was

49:11

uh, presented at RSNA last year, that they

49:13

were very successful at over 94 and 96%

49:18

sensitivity for identifying these serrated

49:22

polyps, um, based on size, but very successful,

49:26

um, because they used an AI algorithm

49:28

that actually found contrast coating

49:30

on the surface of these serrated, uh, polyps.

49:35

These are some of the active areas of, uh, research,

49:39

um, that I think will take us through the next

49:42

five years or so. It's really, you know, is there a role

49:45

for CTC in the younger-than-50-year-old patients?

49:49

Um, and we need to evaluate and, um, uh, perform

49:52

some of the validation studies in younger patients.

49:56

We really need to continue to look at minimal prep

49:58

CTC. If we can't entirely get rid of the laxative, but

50:03

to decrease the rigor of, uh, preparation for CTC.

50:07

And I think that we can get there—looking at ultra

50:10

low-dose CTC—and that already, um, has been studied

50:14

and continues to be studied, but to decrease, as I

50:17

mentioned, from the 3 millisievert very low dose

50:20

that we are achieving now to even sub-millisievert,

50:23

so less than one millisievert.

50:25

And then what's the role of some of the

50:26

new technology, like dual-energy CT, which

50:30

we are evaluating here at Montefiore?

50:32

Um, but also, uh, artificial intelligence.

50:35

And this was, um, a study that, uh, looked

50:38

at sub-millisievert CTC, and you can see that

50:41

there was no difference in image quality.

50:43

This was a small pilot study of only 26

50:46

patients, but you can see that low dose

50:49

for them was at less than one millisievert,

50:52

um, without compromise of image quality.

50:55

What about dual energy?

50:57

Um, well, um, in this one study,

51:00

again, this was a pilot-type study.

51:01

They did not use, uh, oral

51:03

contrast, but they used IV contrast.

51:06

You know, the sensitivity didn't really

51:08

change because it was already fairly high.

51:10

You can see that with the use of the iodine map

51:13

from dual CT, we were able to achieve a very high

51:18

specificity, much higher than with conventional CT.

51:22

Here's an example from that study, giving IV

51:24

contrast, where you can see that stool showed no

51:27

iodine content on the iodine map,

51:31

whereas, um, this polyp—I mean, I'm sorry—this

51:34

large polypoid carcinoma showed enhancement,

51:37

high iodine content. And polyps in general, um,

51:40

outside of carcinoma even, uh, tend to enhance.

51:43

So with IV contrast, I just wanted to bring to

51:47

your attention that there is a C-RADS out there,

51:50

and I leave it here for you to, uh, take a look at.

51:53

But, um, we are in the process through the

51:56

American College of Radiology Colon Cancer

51:58

Committee

51:59

revising the C-RADS classification, but

52:01

this is still in use—with C1:

52:04

normal study; C2: one or two small

52:08

polyps that are in the 6–9 category;

52:11

C3: one large polyp or three or more of

52:14

the small polyps; and C4 is a clear mass.

52:18

And so what is this case?

52:19

A 60-year-old now with a single

52:20

seven millimeter polyp is a C2.

52:24

Here's a 65-year-old with a large 12

52:27

millimeter polyp, and clearly this is a C3.

52:31

There's also an E classification that comes along.

52:34

Um, just to show you—E1 is normal;

52:37

E2: clinically, um, insignificant;

52:40

E3: likely clinically unimportant;

52:43

E4: potentially clinically important—and

52:46

therefore you would definitely need to work it up.

52:49

So here's a patient with, um, a right-sided

52:52

adrenal myelolipoma—clinically insignificant.

52:56

So an E2.

52:57

A patient with what?

53:00

A left-sided—

53:03

you can see—a renal cell carcinoma with all the

53:06

associated adenopathy, retroperitoneum.

53:09

And this is E4.

53:12

Okay.

53:12

I'm just gonna finish off with just

53:13

some reimbursement for those of you in

53:15

the U.S. who might find this interesting.

53:17

And this is the, um, Medicare reimbursement

53:21

rate for physicians, which does not include

53:24

the technical fee, but you can see that for

53:26

CTC it's actually, uh, favorable compared to what

53:29

you would get for regular, um, abdominal CT.

53:34

And of course, the RVU are pretty much double

53:37

what you would get for an abdominal, uh, CT.

53:41

Note that CTC has a, um, CPT code for

53:45

screening, but it's not covered currently.

53:49

So most, uh, private payers in the U.S.—and I

53:53

think many of us don't know this—actually already

53:55

cover for diagnostic, but also for screening CTC.

53:59

And this is—I pulled off from the Aetna, uh,

54:01

website, and they last year already in line with

54:05

American Cancer Society recommendations,

54:08

they decreased the age of coverage to 45.

54:11

But you can see that what I have highlighted

54:13

in red is that CTC is considered medically

54:16

necessary for screening every five years.

54:18

And that's great news.

54:20

This is just a graphic that shows you all the

54:23

different, um, insurers and what they cover.

54:27

And this is available through the American

54:29

College of Radiology, or for anybody who needs this or

54:32

can email me, I'm happy to email it to you as well.

54:35

Congress—

54:36

there's been a bill that

54:38

has been introduced previously.

54:40

We'll continue to introduce bills, uh,

54:42

once, uh, I think Congress is in order.

54:45

Just to show you also that there is

54:47

an active CTC Coalition—really a

54:50

collaborative effort amongst many societies.

54:52

There's a lot of support here, uh, to increase screening

54:55

rates and to include CTC as a valid option.

54:59

And then I just wanted to show you also

55:01

that the American College of Radiology

55:03

last year took over this, um, very,

55:07

user-friendly but important database to

55:11

allow patients and referring physicians—

55:14

this is in the United States only—but

55:17

to find actual medical centers and outpatient

55:20

sites that perform CT colonography.

55:23

And I recommend to you—those of you who

55:25

are listening, who have not joined—

55:28

that you go onto this site and you register

55:31

your site because you'll get more patients.

55:33

And you can easily just Google "ACR

55:36

my CT colonography," find the website.

55:39

Um, it's a very easy registration.

55:41

This is the one page that you have to

55:43

fill out, and then your site will be, uh,

55:45

registered and available for patients to see.

55:49

And just my last two slides really is

55:52

that I really wanna say that I think that

55:54

CT colonography does have a role, you know,

55:57

in current, uh, climates with the pandemic.

56:01

Um, there is, uh, compared to more invasive tests

56:04

like colonoscopy, a lower likelihood of perforation.

56:07

I mentioned before that there's a 10,

56:09

10 to 20 times lower likelihood of

56:12

perforation compared to optical colonoscopy.

56:15

Um, and therefore less likely to require an

56:17

inpatient bed during an active pandemic.

56:20

Um, there is no sedation that's required.

56:23

Um, so you don't require somebody to come with you.

56:26

Um, they don't sit in the waiting room with you.

56:28

So it allows for better social distancing,

56:31

um, because you don't give anesthesia, less

56:34

likely, uh, adverse reactions and again,

56:37

less likely to require an inpatient bed.

56:40

Um, and then because you're not using,

56:42

uh, sedatives, you can save, uh, the

56:45

sedatives—propofol, for example—

56:47

um, for COVID patients who are

56:49

on, uh, ventilators. Very easy.

56:53

We usually do this anyway.

56:54

This is schedule CTC first thing in the morning,

56:56

since patients are NPO.

56:59

But a lot of vulnerable older patients like to come

57:01

in early, um, when it's less crowded, um, and to have

57:05

their imaging tests, and we can easily accommodate.

57:08

It's a shorter procedural

57:09

time compared to colonoscopy.

57:11

There is definitely less contact

57:13

with healthcare workers. For CT

57:14

colonography, it's really the technologist,

57:16

maybe nurse. For colonoscopy,

57:19

you know, they have to have an IV put in.

57:21

Um, they have to recover, uh, from the sedation.

57:26

Uh, you've got your gastroenterologist who's in there.

57:30

Uh, sometimes you require an anesthesiologist as well.

57:33

So, um, there's more exposure, I think, to

57:36

healthcare workers, um, with a colonoscopy.

57:39

And then for CTC, there's decreased need

57:42

for PPE because fewer healthcare workers are involved.

57:45

And then also to remember that CTC is a

57:48

structural exam, unlike stool-based tests.

57:51

So we can actually, when we find a

57:53

lesion, tell the gastroenterologist,

57:54

"Look here. Look at this segment, uh, this many

57:58

centimeters away from the rectum, um, and how many

58:01

lesions," and can decrease and help the

58:05

gastroenterologist, uh, find lesions more easily.

58:09

So my summary points are that for you to remember

58:13

is that there has been a significant increase

58:16

in early-age onset, uh, colorectal cancers.

58:19

Um, and this has, uh, led to the American

58:21

Cancer Society decreasing the recommended

58:24

start time, uh, for screening to age 45.

58:28

Um, I think that we have to be aware of this

58:31

third pathway, uh, to development of colorectal

58:35

cancer—the serrated, uh, polyps.

58:38

Um, remember to use positive oral contrast.

58:40

The majority of serrated polyps will have this

58:43

contrast coat, and this will highlight them

58:46

for you to be able to find them more easily.

58:49

And finally, you know, we're in such a

58:51

strange, um, challenging time right now.

58:55

Um, and many, uh, patients have put off, uh,

58:58

screening tests, including colon cancer screening.

59:01

I think that, um, this is a mistake and,

59:04

uh, will, um, likely find many patients,

59:08

more patients with, uh, late-stage disease.

59:11

Um, and so, um, CTC can be used now as

59:15

a safe complement to colonoscopy where

59:17

colonoscopy is not easily available.

59:20

Um, we can use CTC during the pandemic and,

59:23

and it really does offer, um, many advantages

59:26

as I have enumerated during the talk.

59:29

So thank you for your attention.

59:31

Um, and I'll see if I have a few minutes

59:35

maybe to answer some of the questions here.

59:38

That'd be great.

59:42

I'm sorry.

59:43

Okay.

59:43

Let's see.

59:48

Okay.

59:49

Um, how do you determine suboptimal bowel preparation

59:53

that warrants postponement of the procedure?

59:57

So, um, the answer would be that if you, uh, take a

60:01

look, uh, technologists can see this on the scout view,

60:05

they see, um, stool, uh, throughout the colon.

60:10

Obviously, that's not a well-prepared colon and you

60:13

wouldn't even need to perform the axial images.

60:16

However, um, if you can't tell on the scout and

60:19

you perform the axial images, uh, and you see,

60:23

uh, adherent stool, um, that covers, uh, a large

60:28

portion of the colon, obviously that's not well pre—

60:31

but if you cannot, I think the key here is that if

60:34

you cannot exclude a six millimeter or larger polyp…

60:39

You need to, uh, redo the CT colonography after

60:44

additional preparation or repeat preparation.

60:48

Um, so I think that is the key.

60:51

Next question is time required

60:53

for the CTC examination.

60:55

Um, and I wasn't sure whether you meant,

60:58

uh, for the actual scanning and or whether

61:02

to interpret, and I'll answer both for you.

61:04

So we typically will, uh, schedule

61:08

the CTC exam at half hour intervals.

61:11

Should take you at most, um, to get the patient, um,

61:15

to do one last evacuation, um, in the bathroom to

61:19

empty the rectal vault, get the patient on the CT

61:22

scanner, uh, table, um, put the rectal tip in, inflate,

61:27

um, and sometimes it takes you to rotate the

61:30

patient in order to get adequate, uh, distension.

61:33

Um, but to do the scan, to assess, uh, whether

61:37

you have, uh, adequate distension, adequate

61:39

cleansing, and then to scan to find a problem

61:42

should take you, um, really about 20 to 30 minutes.

61:46

Should take no longer than that.

61:48

So that's for, you know, the actual procedure time.

61:52

Um, for interpretation, um, I, I mentioned the,

61:57

uh, study that was performed by ACR that said

62:00

that you should use at least 20 minutes or more.

62:03

And, uh, I would agree with that.

62:05

I think that once you become more of an expert

62:08

reader, I can tell you, for example, I've read

62:10

thousands of these exams and for me to read, you

62:13

know, both the colonic and the extracolonic,

62:15

um, takes less time than the average, uh, reader.

62:18

So for me, I can read probably in 10 minutes or less.

62:22

So it does require, you know, experience.

62:25

Um, but, but um, in general you should spend,

62:29

um, about 20 minutes or more, uh, for a CTC exam.

62:32

And again, that's based on the number

62:34

of lesions that are present, um, and

62:36

how well cleansed, uh, the colon is.

62:41

Not all stool has air.

62:42

How would you differentiate from polyp?

62:44

Uh, that's a great question, and I would say that, um,

62:48

this has been one of the reasons why we so strongly

62:52

recommend that you perform tagging, because early in

62:56

the years when we started performing CT colonography,

62:58

and this is now, you know, 10 to 15 years ago.

63:02

Um, it was very hard for us to distinguish

63:06

homogeneous, uh, adherent, uh, rounded, uh, stool.

63:12

Uh, and it completely looked like, uh, a true

63:15

polyp. We would wind up sending these patients on to

63:19

colonoscopy, uh, when they didn't need to be.

63:22

And I think that with tagging, um, oftentimes you

63:26

will get, you know, most of the stool will be tagged

63:28

if the patient adheres to the protocol.

63:31

Um, but you will have some mixing of

63:34

the, um, barium product or the

63:37

iodinated, um, product, uh, with the stool.

63:40

Uh, and that helps you to, uh, distinguish

63:43

a stool from, um, a true polyp.

63:46

You have to be careful.

63:47

Some polyps can have a coating, as I mentioned, even

63:50

the rounded, donated polyps and sessile polyps that are

63:53

rounded can have a coating, not just the flat lesions.

63:57

Um, but I would say that, uh, you know, for a

64:00

larger lesion you should have some, um, uh, high

64:05

density, uh, contrast in the center of the lesion.

64:09

In order to call it a stool. If it's only on the

64:12

surface, it's more likely to be a true polyp.

64:17

Okay.

64:18

And I think that is the last question that I see.

64:22

Perfect.

64:22

So as it brings us to close,

64:23

I just wanna thank you,

64:24

Dr. Yee, for your time today.

64:25

We really appreciate it.

64:26

And thanks to all of you for

64:27

participating in this noon conference.

64:28

A reminder that it will be made available

64:30

on demand, uh, complimentary at mionline.com, in

64:32

addition to all our previous noon conferences.

64:34

And tomorrow we'll be joined by Dr. Amy Patel

64:37

for a lecture on breast MRI: the basics and more.

64:40

Thank you and have a wonderful day.

64:42

Thank you everyone.