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Hello and welcome to Noon Conference, hosted by MRI Online

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Noon Conference connects the global radiology community

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through free live educational webinars that are accessible

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for all and is an opportunity

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to learn alongside top radiologists from around the world.

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by creating a free MRI online account.

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Today we are honored to welcome Dr.

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Brian Gura for a lecture entitled Cardiac

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CT in Practice From Prevention to Post Revascularization.

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Dr. Gura completed his radiology residency at the Western

0:39

Pennsylvania Hospital

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and his cardiac imaging fellowship at Massachusetts

0:43

General Hospital.

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He leads the cardiovascular imaging section

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as academic chief, having also served in the roles

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of Division Chief Program director,

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and has directed the cardiac CT

0:55

and MRI programs for over a decade.

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He is a past president of the Society

1:00

of Cardiovascular Computed Tomography

1:02

and has, has over 200 peer reviewed publications in the

1:06

field of cardiovascular imaging.

1:08

At the end of the lecture, please join Dr.

1:11

Gura in a q and a session

1:12

where he will address questions you may

1:13

have on today's topic.

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Please remember to use the q

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and a feature to submit your questions so we can get to

1:19

as many as we can before our time is up.

1:22

With that, we are ready to begin today's lecture. Dr.

1:26

Khara, take it from here.

1:28

Thank you for the intro.

1:29

Um, and thanks for the opportunity.

1:30

What a, what a cool little way to educate.

1:33

Um, I, uh, so wanted to start things off real basic

1:37

and go back to the very first coronary imaging.

1:41

This is, uh, the very first publication of coronary imaging,

1:45

not just cardiac ct,

1:47

and it was in actor radiologic in 1945, so slightly

1:50

before I was even born.

1:52

Um, and this is the best image that, that you can find from

1:57

that, uh, publication.

1:59

And you can see the aortic root here, um,

2:01

with the demarcated with the white

2:03

and some arrows on

2:05

what they thought were the coronary arteries.

2:07

I think they're probably right.

2:08

Um, they were doing this with a trans sternal puncture, uh,

2:12

in order to opacify the aortic root and coronary arteries.

2:15

So, not the safest thing to do,

2:16

but it was, uh, very appealing to be able

2:18

to image coronary arteries, as you know, uh,

2:20

currently the number one, uh, cause of, uh,

2:23

mortality in the Western world.

2:24

Now, the, um, the appeal of coronary imaging

2:28

through the vessels, uh, was, uh, a lot safer.

2:32

And, uh, by the way, that that method was quickly abandoned

2:34

after five patients.

2:36

The, um, this is the first

2:38

invasive angiogram done at the Cleveland Clinic.

2:40

Uh, also, um, not super safe, and this was an accident.

2:44

It was, uh, mason stones here doing the, the calf,

2:48

and there's a great writeup of how it all went down.

2:50

Uh, they were actually looking at the valves in a congenital

2:52

or a rheumatic heart disease patient.

2:54

And, um, the catheter slipped in.

2:57

Uh, contrast is very ionic, and this caused asystole.

3:00

It was a brief episode. Patient did fine.

3:02

But, uh, this is the first image of a coronary, uh,

3:05

done angiographically.

3:07

And these days we have flexible catheters, safe,

3:09

low osmolar contrast, uh, cine, uh, digital angiography.

3:13

And so you can see that it's, it's become more routine.

3:15

Not totally routine, but more routine to look at,

3:18

uh, coronary arteries.

3:19

And you can also do therapies invasively,

3:21

but there's still some risks.

3:22

So, um, the first cardiac CT

3:26

was actually done in 1977.

3:28

So, um, the way publications go, as I know it,

3:31

it might have been conducted before I was born,

3:33

but certainly published after I was born.

3:34

You know how peer review was, uh, back then,

3:37

but names, you know, so Dr.

3:38

Hounsfield was one of the co-authors,

3:40

and the idea was to kind of hack together an ECG gated, um,

3:44

mechanism that you could do a coronary C

3:46

or cardiac CT with not a coronary ct.

3:48

They were looking for a lead in the coronary sinus,

3:50

and it was successful,

3:51

but it was just, uh, an early application.

3:55

And then these days, now we can, we can routinely do, uh,

3:58

CT angiograms like you see on, on the right of your screen.

4:01

This is just a volume rendered image,

4:02

but you can do it in between one

4:03

and three heartbeats depending on the vendor you're using.

4:06

Um, just a touch of radiation.

4:07

You may or may not need, uh, medication

4:09

to slow the heart rate or

4:11

to dilate the coronaries depending on the protocol,

4:13

but it's become, um, much more ubiquitous.

4:17

And, um, you know, it's interesting

4:19

'cause if you, if you take a look at that first, uh,

4:21

publication with Dr.

4:23

Hounsfield at all, they kind of, uh, speculated the field

4:26

as it came to exist.

4:27

So they did think that a CT scanner capable

4:30

of collecting the attenuation measurements within 50

4:32

milliseconds or less, would be an ideal system, uh,

4:35

for stopping cardiac motion.

4:37

But such equipment does not exist.

4:39

Still true today, the fastest scanner that I'm aware

4:42

of is 66 milliseconds, temporal resolution pretty close.

4:45

And I think close enough is actually really good.

4:47

Uh, the other thing, uh, is they, they kind of, uh, thought

4:51

through how a field might evolve.

4:53

And, and what we see here is, um,

4:55

just laid out in a little timeline.

4:57

There's kind of a gap after cardiac CT became possible.

5:00

There was some electron beam scanning done due

5:02

to calcium scoring only in the 1980s.

5:04

Um, and then when multi detector CT came along, um,

5:07

during the times when I was in training, um,

5:10

that made body CTA possible coronary, CTA, uh,

5:14

we get into functional imaging.

5:16

And then these days now we're doing even post-processing,

5:18

which kind of adds things

5:19

that couldn't even be seen, uh, invasively.

5:22

So we, we've sort of seen a field, uh, go from the fringes

5:25

to the mainstream and, and, uh, fairly, um,

5:29

rapid accelerating, uh, timeframe.

5:32

If you look at that again, first publication, um,

5:34

they thought, Hey, well, it might be a way to, uh,

5:37

triage patients su with suspected

5:39

or known myocardial infarction.

5:40

And we'll talk about that today. Um, you'll be able

5:42

to separate patients with, uh, uh, coronary disease

5:45

that need further treatment.

5:46

So all these things actually go on, um, in, in, in the time

5:49

of, of, uh, of a very short recent rapid adoption.

5:53

Um, so let's start with a couple applications.

5:55

Number one, uh, calcium scoring.

5:57

So, uh, the main question for calcium scoring is,

6:00

do I need to take a statin?

6:01

And there's some other preventive medications.

6:03

Uh, the, the visionaries will tell you there's 14 different

6:06

classes of, of, uh, preventive therapies right now.

6:08

But, um, the, the bulk of it is still, uh, statins for now.

6:12

Um, it should not be done just to have a look.

6:15

It should not be done for cabbages.

6:17

You often get these requests come through our marketers,

6:19

Hey, hey, I had a cabbage.

6:20

I want to know what my, uh, calcium score is.

6:22

It's not relevant anymore.

6:23

In fact, your calcium score will go up in the native vessels

6:26

that have been bypassed because they're not being used.

6:29

Um, it's not a poor man CTA.

6:30

So if someone wanted a CTA, but insurance won't pay for it,

6:34

and they're willing to self-pay

6:35

for a calcium scoring, do not do it.

6:38

Um, and really just like any imaging test, um,

6:41

you shouldn't do the calcium scoring scan

6:43

unless it's going to change management.

6:45

So if it's never going to, if you just want to do it

6:47

to do it, um, that's not a good reason.

6:49

Um, a lot of people ask, is it, uh, okay to do it?

6:52

If I've had one a while ago,

6:54

and the answer is, it might be, um,

6:56

if your calcium score was zero

6:57

and it's been five years, there's a little bit of data

6:59

to show that you can keep avoiding, uh, medications

7:02

until you progress off baseline.

7:04

So, um, fair enough to think about, uh,

7:06

repeating one at some reasonable interval.

7:09

And, uh, there's just a small amount of data for that.

7:11

So it's not a tremendous amount.

7:12

There's also a, a conflicting data, some of which shows

7:15

that if you do have calcium, um,

7:18

and you're on a statin, you may actually get more calcium.

7:20

So you don't necessarily need to, um,

7:23

repeat ones that are positive.

7:24

So that, that's another, um, thing.

7:26

It's really, it's, it's should be the thoughtful plan

7:28

that I'm going to start a medication, um, if I have one,

7:32

or discontinue one if the scan is negative,

7:34

but not just to kind

7:35

of follow it like a lab value over time.

7:38

So I, I put up six, uh, uh, patients here, um, just

7:41

to give you reasonable uses and one that's not reasonable.

7:44

Um, so a 56-year-old woman, I didn't give any other history,

7:48

and you can see her calcium was zero.

7:50

So, um, that would indicate to her that the, the likelihood

7:53

of, uh, coronary artos sclerosis is low.

7:56

Um, 50-year-old, 52-year-old man

7:58

with hypertension and family history.

7:59

So he's intermediate risk, so he's kind of ideal.

8:01

Um, you can see that there is calcium.

8:03

I don't know what the number would be.

8:04

Maybe it's a hundred, 150.

8:05

Um, that would be reasonable

8:07

to start a statin in a man like this.

8:09

Um, here's a 44-year-old woman with chest pain.

8:11

Uh, not an appropriate use.

8:13

This is not a calcium scoring done in oscillation.

8:15

I'll show you why this is a very

8:17

inappropriate use in a few minutes.

8:19

How about a 23-year-old male smoker? Uh, it's kind of low.

8:22

We don't really have data on, um, patients

8:24

that are under 45 to know that.

8:26

And it's unlikely that he would have calcium,

8:28

so it's not a great indication.

8:30

But if for some reason, um, we wanted

8:32

to do some quantitation in him, maybe, um, for a 50

8:36

to old woman, that's a smoker,

8:38

and low HDL, those are putting her

8:40

at at least intermediate risk.

8:41

And you can see she does have calcium.

8:43

So this would change her therapy

8:45

and, uh, say that she deserves to have a, a statin, um,

8:49

if she, or to help her, uh, accept the fact

8:51

that she has atherosclerosis and,

8:53

and then, uh, hopefully convince her to take a statin,

8:56

which should, uh, help her, uh, prevention.

8:59

Um, and then this is an 69-year-old, um, person

9:01

that's asymptomatic and anxious.

9:03

Um, so, uh, it's a soft indication.

9:06

Um, if you get much older than this, we don't have data.

9:09

We know that, uh, atherosclerosis happens more with age.

9:11

So the likelihood of finding plaque, um,

9:14

becomes very high at older ages.

9:16

But often you'll see that people even in their eighties, um,

9:20

sometimes don't have any, um, calcified plaque.

9:22

Uh, in this case, this person, uh, was asymptomatic,

9:25

but they wanted to know more.

9:26

And maybe that helps them, uh, take preventive therapy.

9:29

But basically, I put it in

9:30

red right in the middle of the screen.

9:32

It really should be for, uh, asymptomatic patients at low

9:36

to intermediate risk for atherosclerosis.

9:38

So, um, not super high risk, not no risk.

9:41

And, um, they should be asymptomatic.

9:43

You'll see some guidelines

9:44

that talk about expert use in patients that, uh,

9:47

have vague symptoms, but should be done extremely carefully.

9:51

I personally wouldn't, uh, advocate for that.

9:53

Um, how does it work in the real world?

9:55

But there's not a ton of massive studies that are recent.

9:59

Uh, the most, uh, recent one I'm aware

10:01

of is the KOVUS trial.

10:02

Um, and so that's a trial done in Europe,

10:05

and they took a very large population, um,

10:09

and, uh, they offered, uh, calcium scoring as part

10:12

of a little bigger screening effort.

10:14

And, um, they screened a lot of people.

10:17

They limited it to men

10:18

because that's what the data that they had informing it.

10:21

Um, and they limited it to men age 65 to 74,

10:24

and they didn't show a survival benefit.

10:26

So that's one thing they remember is when you're doing

10:28

imaging, you have to then result in a management change,

10:31

which then results in, um, a positive benefit.

10:35

And so in this relatively elderly group of men, um,

10:39

there's a lot of competing risks.

10:41

And so they didn't show a, uh, decrease in mortality

10:44

and those that were offered

10:46

and completed the, the, uh, calcium scoring screen,

10:49

and they also looked for aortic

10:50

aneurysms and some other things.

10:51

But it does, um, show a trend towards significance.

10:54

And you could imagine if you shift this earlier

10:57

and earlier, you know, we usually have good data now

10:59

to say it's, we know where, what to do

11:01

with your calcium scoring age 45

11:02

and above, um, that there might be benefits,

11:05

but the time to accrue that benefit to say,

11:08

I've put you on a statin long enough

11:09

to prevent a future mi takes longer to do.

11:11

So it becomes a very difficult, um, uh, study to do to, to,

11:16

to show benefit and run the trial long enough, um,

11:19

that these small changes in management, um,

11:21

benefit people net.

11:22

So right now, we don't have good data to say, Hey, offer it

11:25

to the world or offer it to this subset of the world.

11:28

Um, but this comes up a lot

11:29

and it's often, uh, gonna come up in, um, in your practice.

11:34

I, um, uh, I'm just making sure I don't miss the chat here.

11:39

Okay, so, um,

11:40

and just like in a summary figure that I grabbed off of, uh,

11:44

uh, nice, uh, summary, summary slide here.

11:48

Um, but you're looking for relative risks

11:49

in the all course mortality.

11:51

All cause mortality is, uh,

11:52

somewhat higher in in a group like that.

11:54

Uh, I'll let you, uh, dig on that later if you're like,

11:57

okay, let's move on to coronary CTA.

11:59

And the main question there is, is there obstruction?

12:01

And secondarily, is there any plaque?

12:04

Um, it's not just to have a look.

12:05

It's not 'cause a podcaster said, I need one.

12:07

It's not 'cause a marketer said I should have one.

12:09

I get this a lot lately. Uh, it's not that I,

12:12

if it's one change management.

12:14

So if you not gonna start a statin, no matter

12:17

what the study shows, or you're not gonna consent

12:19

to doing your vascularization,

12:21

you may not want to have that look.

12:23

Um, and you shouldn't do it

12:25

if there's a more appropriate test.

12:26

So if you're really high risk

12:27

and patients got a lot of stents or a bypass graft

12:30

and you're really looking for a profusion, do

12:32

that test instead of a coronary CTA.

12:34

But, um, again, uh, assuming that there's a reason,

12:37

a symptom, um,

12:39

or a intended management change, um, may be reasonable

12:42

to do a CT angiogram.

12:43

And there's nothing more, um, direct

12:46

of a feedback loop than the emergency.

12:48

So I'll, I'll use some examples from emergency

12:50

cases with chest pain.

12:52

There's level one a evidence that there's benefit to this.

12:55

Um, and there's nuance in who we select for the test.

12:59

But, um, basically it should be people with symptoms, those

13:02

that are low to intermediate risk.

13:03

And again, only if it's gonna change management.

13:05

So patients getting admitted anyway,

13:07

'cause they have a arrhythmia.

13:08

You might do a CTA only at the request

13:10

of the admitting cardiologist who needs to know that I'm,

13:13

they're not dealing with obstructive disease.

13:15

Or, um, if it's a stent patient

13:17

and the cardiologist is gonna catho no matter what,

13:19

don't just layer in A CTA because you're just adding costs

13:22

and, and a potential comorbidity without

13:25

benefit to the patient.

13:26

Uh, so this is a patient, um, that I happen

13:29

to interpret in the Romi CAT two trial,

13:31

which was done over 10 years ago.

13:33

Um, the patient qualified,

13:35

they had negative initial lab work

13:36

and ECGs, you can see we found an RCA obstructive stenosis

13:40

and confirmed that, um, in the cath lab, uh,

13:43

shortly afterward.

13:45

And, um, uh, it, it accelerates care.

13:48

It keeps them from being parked in the ed.

13:50

And, um, it keeps us from sending someone like this

13:53

home without doing anything.

13:54

Um, the cost of, uh, chest pain ed workup is, uh,

13:58

this is actually 10-year-old data now.

13:59

Um, $7 billion a year in the US alone.

14:03

So I guess inflation maybe, maybe it's double, I don't know.

14:06

But, um, it's extremely expensive.

14:08

And the main cost isn't imaging or healthcare.

14:10

It's actually opportunity costs.

14:12

So, uh, someone like you

14:14

or I, that's a productive radiologist

14:15

or cardiologist, uh, that might be practicing, um,

14:18

but is stuck in an ED doing a rollout

14:21

and there's a tremendous cost to society.

14:23

So, um, there's that cost.

14:25

And there's also, I don't know about your hospital,

14:27

but ours is full, um, pretty much daily.

14:29

So we park patients in the hallways while we wait for tests.

14:33

And there's always pressure to free up that bed.

14:36

CTA is a great way to do it.

14:37

This patient I'm showing you here is in atypical,

14:39

it's a less likely you find obstructive disease,

14:41

more likely there's an alternative cause of chest pain

14:44

or just a non, uh, atherosclerotic cause.

14:47

So, um, those beds can be freed up quickly.

14:49

Um, this is a, uh, from that trial, the Romy CAT two trial,

14:53

the key figure just showing

14:54

that there's significantly shorter length of stay

14:56

for CTA versus standard of care, same year in the same, uh,

14:59

local TR Trade Society journal, the New England Journal, um,

15:02

there was a, a study by Harold Lit in the Akron PA trial.

15:05

They showed safety of CTA, this shows efficacy.

15:08

Um, and if you look at this, the, uh, the median time

15:11

to disposition from an ED was 8.6 hours in the CT arm.

15:15

And then the non CT arm, it was, uh, 26.7 hours.

15:20

So about a nursing shift versus o over a day.

15:23

Now, the, um, the study was done in a

15:28

randomized controlled fashion, tightly controlled 10,

15:31

11 hospitals around the country.

15:33

And, um, there's, uh, some caveats

15:36

and one of those that was run during banker's hours.

15:38

So in modern times, you may not offer a CT eight 3:00 AM

15:42

but you'd scan the patient the next morning.

15:43

So maybe the numbers won't apply.

15:45

We've actually seen improved, uh,

15:47

local data versus this trial.

15:49

Just as the system has become more comfortable with CTA all.

15:53

So how do we report these, whether it's in the ED

15:55

or as an outpatient or anywhere in between,

15:57

you report using ca rads, um,

15:59

just like birads, there's a RADS for that.

16:01

And, um, you, you want to basically, uh,

16:05

use this standard therapy standard verbiage.

16:07

There's actually zero through five.

16:09

And there's n So n means non valuable.

16:11

If you can't see the arteries, well,

16:13

you can't say they're negative.

16:14

You have to assume you're missing something.

16:16

And so n means, i, I don't rule out obstructive disease.

16:19

So setting that aside

16:20

and setting occlusion, which is pretty straightforward, um,

16:23

you have these four grades that we worry most about.

16:26

Um, cadrad zero means there's no plaque, no stenosis.

16:29

Those patients can be dispo from the ED with impunity.

16:32

Um, even CAD red's one and two.

16:34

So non-obstructive disease,

16:35

nothing less than nothing more than 50% narrowing.

16:38

Um, even if this plaque, you might add a statin

16:41

or other preventive meds, but you're not going to admit,

16:44

because you know that invasive

16:45

angiogram probably won't even show anything.

16:47

Even in cadrad one, um,

16:48

I matched up a calf for the rest of them.

16:50

So CADRAD two here, you see lots of calcified and,

16:53

and some noncalcified plaque.

16:55

Uh, and you can see there's a rough luminal narrowing.

16:57

That's, you know, certainly less than 50%.

16:59

Um, this one's probably on the order of like 20

17:02

to 30% narrowing.

17:03

That's cadrad two. So it is mild stenosis.

17:06

You've certainly justified medications,

17:08

but you don't, uh, have anything

17:10

that you would do therapy on.

17:11

Nothing needs a stent, nothing needs a cabbage.

17:14

Um, by the way, your CADRAD score comes

17:15

from your worst stenosis.

17:17

So say that you have two vessels with no plaque at all,

17:20

and one with, uh, intermediate 50% stenosis.

17:23

Your CAD red's greatest. Three.

17:25

If all three your vessels have mild stenosis,

17:27

well your CAD red's too.

17:29

Um, so we don't distinguish for the bulk, the,

17:31

the base number, um, the number of vessels, just the,

17:34

uh, the worst stenosis.

17:35

And even though we worry a lot more about plaque these days,

17:38

'cause there's more therapies, the base score comes from

17:42

destruction, destruction.

17:43

And then everything else comes from the, uh, additive value

17:45

of the plaque scores, which you can use calcium scores,

17:48

you can count up the segments with any plaque.

17:50

Um, and the cadres, uh, guideline, they're freely available,

17:54

uh, detail, you know, how you score the plaque,

17:57

but the base number still is, is their obstruction.

17:59

Uh, and that's what you should focus most on.

18:02

Cadres three here is moderate.

18:03

It's 50 to 69% diameter stenosis, but it, it's intermediate.

18:07

Um, we know coronary, uh, blood flow, uh, goes up fourfold,

18:11

uh, during times of exercise.

18:13

So, um, this fixed obstruction may become more, um,

18:16

significant during peak exercise

18:18

or just during times of stress.

18:20

Um, and you can see here I put lots of arrows on the

18:23

noncalcified and a touch of calcified plaque, uh,

18:25

causing this moderate stenosis.

18:27

Here's the same lesion in the cath lab.

18:29

This is the LED of A of a, uh, patient.

18:32

And what you see here is that they had symptoms,

18:35

they had this intermediate stenosis,

18:37

and even in the cath lab, they said, really,

18:40

for sure blocked, it's kind of intermediate.

18:42

And they did something called an F fr.

18:44

So fractional flow reserve.

18:46

Um, and that's putting a flow wire across it

18:48

and then giving intra coronary adenosine.

18:50

So think of it as a stress test causing hyperemia.

18:53

Uh, but just for that vessel, this one's positive.

18:55

The threshold is 0.75 or 0.8 depending on, um, who you read

19:00

and which trial you want to believe.

19:01

But this is well within the drop below.

19:05

Um, normal pressure, if you have no drop, it's a one.

19:08

And so, um, the invasive fractional flow reserve tells you

19:12

that this is likely to be the cause of chest pain

19:15

and that the patient is likely

19:16

to get better if you stent that artery.

19:18

And that's exactly what they did, and you did get better.

19:20

Um, if you see other verbs like

19:23

or other acronyms like IFR, um,

19:26

that's instantaneous free wave ratio.

19:28

There's a couple alternatives,

19:29

but the, what we know from the calf literature is

19:32

that even in interventional cardiologists though,

19:34

they rule the earth, um, know their fallible

19:36

and they need the adjunctive, uh,

19:39

tests in these kind of intermediate lesions.

19:42

And so doing something objective

19:43

that lets them look at the physiologic consequence

19:45

of said stenosis is helpful.

19:48

We'll come back to that concept,

19:49

uh, a little later in this lecture.

19:51

Um, and then cadres four is obstructive, so it looks severe.

19:54

And you can see here that it looks in the, uh,

19:56

where the red arrows are, as if there's no lumen at all.

19:59

But we know if you're less than 1.5 centimeters long, um,

20:02

it's more likely a subtotal

20:04

occlusion than a total occlusion.

20:05

And so it's a 99% stenosis.

20:07

And that's exactly what I'm showing you here.

20:09

That's the case I showed you. I just turned it on its side.

20:11

Um, and so that's a, uh,

20:13

lipid rich plaque causing a very severe stenosis.

20:16

You can see a hairline lumen with the angiogram,

20:18

which has a far better resolution spatial resolution

20:20

than a the base CTA.

20:22

Um, and if this is only one vessel, it's CADRAD four A.

20:26

If you have it in two vessels for a

20:28

but three vessels, meaning it's gotta have the circumflex

20:31

territory, the, the LEE territory

20:32

and the RZA territory that's three vessel disease.

20:35

Um, or if it involves the left main,

20:37

and we call those cataracts four B,

20:39

we know those patients do better

20:41

with bypass surgery than stenting.

20:42

And so that's why there's the distinction

20:44

and that that's remained true for decades.

20:47

So despite all the massive events as advances in stenting

20:50

and, and, uh, percutaneous therapy, um, you live longer

20:53

and do better if we do bypass surgery

20:56

to revascularize in left main disease.

20:58

And you use a low threshold of 50% for left main,

21:01

so much myocardium at risk,

21:03

and there's not really an intermediate grade stenosis there

21:05

or disease in all three vessel territories.

21:08

Uh, okay, so we're in the ed

21:10

and you get this set of patients.

21:11

I just, um, stole these, uh, images off of the internet.

21:14

You probably recognize at least, uh, Pedro there.

21:16

So the, um, the issue with, uh, um,

21:21

the patients that present in their faced

21:23

by their referring physician,

21:24

whether they're an emergency physician

21:26

or a cardiologist, is it's very, um, difficult

21:29

to distinguish who among this list

21:32

of patients will have disease.

21:33

They all have very similarly scary stories.

21:36

You might see something like a TIMMY score

21:38

or a HEART score, um,

21:39

and those scores all just help you assign risk,

21:42

but they don't actually help you definitively,

21:44

uh, manage patients.

21:45

So now I'm gonna show you what their calcium scores.

21:48

So actually cheated that last set

21:49

of calcium scores is actually all these patients.

21:52

Um, now you only are gonna use calcium scores

21:55

for asymptomatic patients, intermediate risk,

21:57

these are all symptomatic patients.

21:59

You cannot stop logistic calcium score.

22:01

And you're gonna see, remember the, uh, the top left

22:04

and the top right images have no calcium at all.

22:06

Um, and so, um, just

22:08

because they don't have calcium, I gotta think this probably

22:10

will have no calcium at all, either the 23.

22:12

But, um, they're all done as part of a CT angiogram.

22:16

You don't have to do a calcium score. I really like it.

22:19

Um, for many reasons, one of which it's a dry run.

22:22

It adds very little radiation,

22:24

and there's no better predictor

22:25

of risk than the calcium score.

22:26

So I'm real, my guard's way up on these, uh,

22:29

two middle patients with lots

22:30

of calcium in their coronaries.

22:31

Same with this guy. So I know now there's athero whether

22:34

it's obstructive is a different animal.

22:35

Um, so we don't stop there.

22:37

But, um, there's actually a couple

22:39

of great papers showing there's no better predictor of risk

22:42

of CAD than a calcium score.

22:44

Um, so just 'cause it comes up.

22:47

Um, if the calcium score is zero,

22:48

is it okay to stop the scan?

22:49

Is it okay to send the patient home? Absolutely not.

22:52

Anytime you've shown up for a CTA outpatient inpatient,

22:55

we're gonna proceed regardless of

22:57

what the calcium score shows.

22:58

But it does help when you're interpreting.

22:59

We also know that a small amount of, uh,

23:02

calcified plaque overlaps the density of contrast.

23:05

So you can have a false negative CTA, uh,

23:08

val in our group wrote this up.

23:10

If you, um, if you have subtle amounts of calcium,

23:14

it can be missed, uh, by the blooming from just the,

23:17

the dense contrast.

23:18

So you might actually call someone a false negative just

23:21

for plaque, uh, in that setting.

23:23

But if you look at large data sets,

23:25

this is the confirm registry over 10 years ago, thousands

23:28

of patients, um, a small number of people

23:30

with a calcium score of zero, we'll have obstructive disease

23:34

of greater than 50%, uh, a small, uh, even smaller number,

23:38

but real number will have obstructive disease over 70%.

23:41

So we're talking people that qualify

23:42

for stents in this yellow and green,

23:44

but have a calcium score of zero.

23:47

Um, and, um, you know that it'll,

23:50

it'll be mostly correct most of the time if you,

23:52

you send the, the negative people home, but not always.

23:55

And that's why you can't stop with a, uh,

23:57

calcium score of zero.

23:58

We also know that the risk of finding disease goes higher.

24:01

So look, look how much more disease you find

24:02

with a calcium score of over 500 when you do the CTA

24:05

and you see, you know, greater than, um,

24:07

70% stenosis often, but not always.

24:10

It's the minority. So you, uh, have a disconnect

24:13

between a calcium score and there's no great threshold.

24:15

Um, the better the scanner get, it's just become,

24:18

in most sites, you're not gonna stop at any, um,

24:21

a any calcium score.

24:22

Even, even if you are not invaluable

24:25

because of really dense blooming in one

24:27

vessel, you might be helpful in another.

24:28

So we never stop that scan. Okay?

24:31

So, um, a myth in, uh, especially

24:33

among emergency physicians can be

24:35

that a low calcium score rules out a CS,

24:36

and the truth is definitely does not.

24:38

Uh, in fact, one of those patients I showed you, uh,

24:41

the top right, uh, had a calcium score of zero,

24:44

had this total obstructive lesion in the LAD.

24:47

It's, uh, it's, uh, at least severe

24:49

and maybe even a, a subtotal occlusion in the LAD.

24:52

You can see the anterior wall is thin here.

24:53

This is a curved planar reformatted image,

24:56

uh, absolutely no calcium.

24:58

And there is the tubular stenosis.

25:00

They anticoagulated her immediately.

25:02

Um, and this is a patient

25:03

with a spontaneous coronary artery dissection.

25:05

You can see it's a fuzzy artery.

25:07

So this wasn't even outta sclerosis.

25:09

This was a tear in the artery.

25:10

She had a really stressful event occur,

25:13

and she actually had a hematoma compressing her LED.

25:16

So be really embarrassing to stop with a calcium score

25:19

of zero and send her home to complete her infarct.

25:22

She did great, by the way, with conservative therapy.

25:24

Okay, so we know that a calcium score of zero is good

25:28

for finding a sclerosis, uh, sorry, good for, um,

25:33

reducing the likelihood of a sclerosis,

25:35

but not a hundred percent.

25:36

So, um, we, we also know

25:39

that a really high calcium score doesn't

25:41

have to equal stenosis.

25:42

So, uh, it's just a marker of risk.

25:44

It's, uh, not even half of a, a coronary CTA

25:49

Let's, uh, let's show the results of those studies.

25:51

So here's the, um, this, uh,

25:52

the top left patient, she was negative.

25:55

Um, this patient had a severe, um, stenosis

25:59

that was stented successfully, uh, in his LED.

26:02

Uh, this is, uh, you know,

26:04

he's even younger than the first patient,

26:06

but, um, uh, with a similar risk profile,

26:08

but had much more significant disease.

26:10

You can see that tight LED lesion there.

26:12

Um, here's our SCAD patient.

26:14

So don't ever count on an calcium score

26:16

of zero ruling you out.

26:17

Um, this patient was actually, um, difficult historian,

26:20

but we knew something was wrong.

26:21

He had a low ef so he had actually bad myocarditis

26:24

that he couldn't articulate, uh,

26:25

and was symptomatic from that.

26:26

His EF was 30%.

26:28

So, uh, we did an MRI and it showed severe myocarditis.

26:31

Um, this is, uh, somebody with three vessel disease,

26:35

so you're counting there the left main as well as LED,

26:37

circumflex and RCA.

26:39

So take your pick, but you get to cataracts four B.

26:41

Um, she just had a kind of a vague history,

26:43

but feels a lot better after her cabbage.

26:45

Um, she also had aortic stenosis that didn't help things.

26:48

Um, and then here's a patient with, uh, I just wanted

26:50

to show you a nukes test so you can see one once at least.

26:53

But, um, here's a, some significant stenosis, um, with kind

26:56

of a, really just a not too impressive history,

27:00

but got a lot better

27:01

after we stented that LED, um, which was the, uh, CTF.

27:05

So the FFR, uh, positive case.

27:08

So if we're in the ed, um, how does the, uh,

27:12

the scan result go?

27:13

Well, most people are getting up in the green

27:15

or the blue here, which means no stenosis,

27:17

or maybe it's mild disease.

27:18

Those patients can go home quickly

27:20

and, um, they don't really need any other testing.

27:23

Um, and then if you find moderate stenosis,

27:25

we often do something else.

27:26

It might be a nuclear test, it might be A-C-T-F-F-R,

27:29

but they often get more care.

27:30

Still, many of them end up, um, dispositioning home, um,

27:34

and, and with medical management, but safely.

27:36

And then if you find severe stenosis,

27:38

they're gonna stay in the hospital longer.

27:39

So I always think of this as like the, the, it's like this,

27:44

the Harry Potter sorting hat.

27:45

You come into the CT scanner undiagnosed,

27:48

and you leave with a coronary status,

27:50

which drives the rest of your care.

27:51

Um, and that's in the ED where you see these hour

27:53

to hour changes in resource use.

27:55

But you see the same thing with, uh,

27:56

outpatients, um, electively.

27:58

It's just takes place over days to weeks.

28:01

Um, here's a, uh, fundamental trial for any cardiologist.

28:05

The, uh, the courage trial, um, named such that

28:10

took courage to say, Hey,

28:11

maybe we can mentally manage patients and not stent them.

28:13

Uh, and this is done, you know, some, uh, over a decade ago,

28:17

but showed no difference in survival by PCI.

28:21

So that's percutaneous coronary intervention versus

28:23

that which is stenting, uh, versus medical therapy.

28:26

So, um, in stable outpatients,

28:28

now we're changing gears from ED here.

28:29

Stable outpatients do just as well with medical therapy,

28:32

and that's a big reason why as long

28:33

as you don't have this high risk anatomy.

28:35

So left main or three vessel disease,

28:37

if you're an outpatient, we can start with medicines.

28:41

Um, in fact, that's been looked at.

28:43

So this is not really imaging related,

28:45

although some of the trials I'll show you in this

28:47

meta-analysis do have, uh, cts part of them.

28:49

Um, they basically showed that in, um, in

28:54

that stable outpatients, uh, with no ischemic heart disease,

28:59

you do not have to stent the, uh,

29:01

the confidence intervals are all centered

29:03

around zero, sorry, one.

29:04

And meaning you don't, you know,

29:06

one doesn't favor the other, so you don't need

29:08

to favor revascularization or not.

29:10

Um, there's always caveats,

29:12

but, uh, I just wanna point out here

29:14

that the Ischemia trial, which is a,

29:16

the most recent big study of, of, uh,

29:19

medical management versus, uh,

29:21

is it was rolled up in a imaging trial.

29:23

Um, medical management versus, uh, invasion still shows

29:27

that, uh, there's no, no harm to waiting around

29:32

and, uh, medically managing very carefully.

29:34

But the, uh, what they did in that, um,

29:36

ischemia trial was they layered in a blinded coronary CTA,

29:40

because they were really testing nuclear

29:42

and profusion imaging.

29:43

Um, but they knew that A CTA

29:45

wouldn't miss left main disease.

29:46

And we know left main is so much worse.

29:48

So they did that and blinded it,

29:50

but, um, they just wanted to make sure

29:52

that if someone was on had left main disease,

29:54

they weren't sitting on it because they thought

29:55

they'd be unethical.

29:55

So even, um, even in the trials

29:58

that look at conservative therapy,

30:00

they wanna know left main,

30:01

if you take one thing from my lecture

30:02

today, don't miss left main.

30:04

So don't depend on a calcium score in symptomatic people.

30:07

And that's, I guess one thing.

30:09

And the second thing will be don't miss left main disease.

30:11

It's so bad that even the, uh, the, the, uh,

30:14

the non-believer cardiologist we're required to use it by,

30:17

uh, by the FDA.

30:19

Now, um, I might be dating myself here,

30:21

but, uh, I was on the tennis team in ninth grade

30:24

and I wasn't very good,

30:25

but I remember Andre Agassi was popular

30:28

and he, uh, he had this, he kind of was a meme before memes.

30:31

Uh, if you remember the story of Andre Agassi,

30:33

he was in a commercial

30:35

before he was famous from Canon, uh, cameras.

30:38

And the tagline was images, everything.

30:40

Um, and I would say most radiologists probably believe

30:42

that I, I certainly did that, the images

30:44

above all else, everything.

30:46

But, um, after I did a cardiac imaging fellowship, uh,

30:49

I would, I'm gonna amend that statement.

30:51

So, um, here's a, uh, and here's why.

30:54

So this is the Scott Heart trial,

30:56

and I think that's very important for you to know

30:58

that trial, um, it was done in Scotland

31:00

and it basically, um, looked at, um, r randomizing

31:05

patients from cardiology clinics with known

31:07

or suspected, uh, stable atherosclerotic heart disease,

31:11

and they got randomized as cts versus standard of cares.

31:14

The survival curves separate immediately upon the ct,

31:17

but it's a very gradual separation.

31:20

CTA does better. And why is that?

31:22

Well, the CTA tells you who has high risk disease,

31:24

so you're gonna find that left main

31:26

or the three vessel, they're just tons of atherosclerosis.

31:28

They're gonna treat what you know, where, whereas standard

31:30

of care, they're using risk factors.

31:32

So you may not even be treating outs sclerosis,

31:34

though you think you are, because risk factors don't always

31:36

translate to disease.

31:37

So, um, the, the Scott Hart trial has been, uh,

31:41

run several times over now,

31:42

and it basically, um, shows tremendous, uh,

31:45

prognostic power, uh, from CTA and plaque.

31:48

And it really comes down to context is everything.

31:51

So Andre Agassi steered out

31:52

of the skid when he was looked as like you.

31:54

And he was, uh, all fluff. He actually won some majors.

31:57

He, uh, shaved his head or lost the wig and, and, uh,

32:01

and he became a respected, uh, tennis great.

32:04

Um, but really what I would say,

32:06

I think maybe he would say too, is context is everything.

32:09

So I showed you, um,

32:11

emergency data showing treat disease immediately.

32:14

I also showed you that medical management works really well.

32:16

And so how do you reconcile that?

32:18

Well, the context in which cardiology is practiced is

32:21

really tantamount paramount.

32:23

So if you, um, look at the, the CAD reds, um, guidelines,

32:27

it's actually two sets of recommendations.

32:30

And we have a macro work

32:32

where we just pick whatever one is relevant.

32:33

So in the emergent setting with chest pain,

32:36

you're gonna manage very acutely depending on CADRAD score.

32:39

So anyone with potential obstruction can get a calf

32:43

or a at least another stress test while they're here.

32:46

And maybe then get a stent.

32:48

If you're severe, you're

32:49

probably gonna go right to the cath lab.

32:50

But the same patients

32:51

with the same results in a stable outpatient

32:54

setting can be medically managed.

32:55

Even the CADRAD four A, they don't, uh,

32:58

have a survival benefit to getting stents immediately.

33:01

Um, so, uh,

33:02

and I'll illustrate that here just

33:04

so you can go through a couple of examples.

33:05

So here's a patient with an intermediate stenosis, uh,

33:09

and hey, what's the correct treatment for this patient?

33:11

Um, is it a stent to the l? Is the LAD?

33:13

So you st sent the LAD, you st sent the C, you don't know,

33:16

um, if they're er emergently having chest pain,

33:19

pretty good data that you have, obstructive disease,

33:21

you should stent 'cause they're gonna do better

33:23

and that's the cause of their pain.

33:25

Um, you certainly aren't gonna cabbage if you only have

33:27

that one vessel, but if they're a stable

33:29

outpatient, it's medical management.

33:30

So you really, this is a trick question.

33:31

The answer is, it depends, depends

33:33

who is this patient and why are they here?

33:36

Um, if you make them a stable outpatient with new angina,

33:39

um, well, it depends

33:40

because you can give them a trial of medical therapy, uh,

33:43

and revascularize later,

33:45

after a number of weeks if they don't get better

33:47

or they just think that

33:48

that's their best way to manage their risk.

33:50

Um, what if they're a, um, just somebody with new angina,

33:54

hypertension, and we do a flow wire, uh,

33:57

an invasive FFR, that's 0.85.

33:59

That's not positive.

34:00

So they're actually gonna do better

34:02

with medical therapy despite this, despite this same degree

34:04

of stenosis that would make a, a,

34:06

a stent appropriate in other settings.

34:08

Or what if they've been that patient?

34:12

Um, they have tried

34:13

for three months on maximum medical therapy.

34:16

And by the way, that trial,

34:17

I showed you the randomized trial with e of equivocal,

34:20

the BODIN trial, the, uh, courage,

34:21

those patients were all maximally medically managed,

34:24

meaning a nurse was calling in

34:25

and said, did you take your medicines?

34:26

I wanna make sure you have the right doses.

34:28

I wanna see the packs that you've actually taken the pills.

34:30

So, you know, you're comparing actual medical therapy versus

34:33

revascularization, but if you fail that

34:35

and you're still having symptoms

34:36

and they do an invasive angiogram,

34:38

and the FFR here is positive, so it's below 0.75, um,

34:42

then the right thing to do is stent that patient.

34:44

And so there's data to support all these things,

34:46

but all of this transpires over months now.

34:50

Uh, okay, so that's the, uh, the context is everything.

34:53

Comment, uh, alright, when you do these studies,

34:55

what are you gonna expect to find?

34:57

Um, I'll show you back to our emergency registry.

35:00

And this dates back 10 years when I was a new

35:02

faculty to try to start things up.

35:03

We, um, found remarkably stable rates of disease.

35:07

So about half of patients won't have anything.

35:10

Oh, by the way, the same rates

35:11

of disease you see in acute chest pain, you tend

35:13

to see in elective outpatients.

35:15

And the reason is there's a very careful,

35:18

so good selection bias going on with coronary CTA.

35:20

There's lots of, um, checks and balances.

35:23

There's prior auth, so you don't want to scan.

35:25

If you're seeing rates much different than this,

35:27

then you may wanna,

35:28

or if you see your own rates changing over time,

35:31

you just wanna make sure you're reading appropriately

35:33

or that you're selecting appropriately.

35:34

And a lot of the selection is done for us these days.

35:37

So I'm grateful in some ways for all that prior auth.

35:39

Um, but, uh, the, uh, you know, roughly half

35:43

of patients won't have obstruction.

35:45

Uh, and this is just, you know, any given month.

35:47

Uh, and I'd compare the month at hand there.

35:49

Um, and,

35:50

and then another, you know, 30 some odd patients will, uh,

35:53

percent of patients will have just mild disease.

35:55

So normal can just live their life.

35:57

Mild disease or, uh, even moderate maybe,

36:00

but mild disease for sure can just be medically managed.

36:02

And then a minority of patients, um,

36:05

should end up in this moderate care category.

36:07

And then severe. And occlusion is fairly rare

36:09

in a CT population.

36:10

If you look at appropriate cath lab patients,

36:13

the disease burden shifts higher.

36:15

There should be a little higher burden to take on the risk.

36:17

A cat's not risk free. You can bleed,

36:18

you can have an MI just from looking.

36:20

So you do see a little less, um, uh, negatives

36:24

and you see more positives.

36:25

So the rates of occlusions are more like 15%,

36:28

but you should be selecting appropriately one of the ways

36:30

as a ct, and it's turned out to be really good.

36:32

Really, nobody in the normal category should need a cath.

36:35

If you're reading appropriately, uh, it doesn't matter,

36:38

you know, what the volume was

36:40

or what the, um, you know, what the, the rates

36:42

of scanning was that we saw.

36:44

Um, these little bands of colors showing you the, the, the,

36:47

uh, disease levels by worse stenosis didn't change for us.

36:51

And they also lined up really well

36:53

with the Roma CATT two trial.

36:55

So I'm just comparing local mass general data,

36:57

which now we have a network of hospitals around the region.

37:00

Um, I'm comparing to RCAT two, which was

37:02

around the country expert sites, Akron, pa

37:05

that was in Pennsylvania.

37:06

A number of sites, uh, hey, these,

37:08

these numbers are relatively similar.

37:11

Monash medical center's ER trial done in, uh, Australia,

37:16

all of them are 80 some odd percent rates of, of, uh,

37:20

disease, uh,

37:21

being under 50% stenosis or maybe even just negative.

37:24

So if you're selecting a Perri, you odyssey, uh,

37:27

predominance of, of negative cases.

37:29

Um, and how does this all work out?

37:32

How does CTA, um, behave with respect to patient outcomes?

37:37

Um, really cool paper from Jonathan Weir McCall at

37:40

all in, uh, Europe.

37:41

You know, it's a UK as a closed system.

37:43

And they looked at counties that had more CT access

37:46

or counties that use SPECT more.

37:48

So CTA shows you plaque

37:49

and obstruction spec just tells you if

37:52

there's unbalanced ischemia.

37:53

Usually you could also end up unlucky like President Clinton

37:55

and have a false negative.

37:57

So balanced disease can be missed by spect.

37:59

Um, but in addition to that,

38:00

SPECT does not really tell you a lot about plaque.

38:03

And when you do the CTA, um, based, uh, testing,

38:06

you find even the non-obstructive

38:08

and it lets you give medical management.

38:09

So five years after they started switching to CTA widely

38:14

because of their guidelines

38:15

and their, um, payment system, you saw that the counties

38:19

with less cardiovascular deaths were the ones

38:21

that had more CT access.

38:23

So pretty cool CT saving lives over time.

38:26

And it's just small signal and it's early, uh,

38:28

but it shows we should look for disease

38:30

and we should respond to it appropriately.

38:32

Often that's not a stent,

38:33

but just medicines, people will live longer.

38:35

Super cool. So what we do matters, okay, hey,

38:38

when to use CTA.

38:39

We've decided based on guidelines that, um,

38:42

uh, we're gonna follow them.

38:44

Um, the, probably the most relevant one is the, uh, 2021.

38:47

If you're in the us, uh, as I am, uh,

38:49

the 2021 chest pain guidelines.

38:51

There are others, there's European guidelines,

38:53

and then there's different, um, societies

38:56

that have different takes on it.

38:57

But what I like about this is they, they kind

38:59

of dispel the notion that chest pain is the only

39:01

presentation for coronary artery sclerosis.

39:03

And they focus a lot on the fact

39:05

that you no testing is often the right thing.

39:07

So, uh, especially with moderate hs troponins,

39:09

like if an ED physician can feel confident, um,

39:13

based on data ruling out a patient with just a lab test,

39:15

and I don't have to do a CT scan, everybody wins.

39:18

Um, and so we see this, you know, things evolve over time,

39:21

but, um, asymptomatic people

39:23

generally aren't gonna need testing.

39:25

Um, and those at low risk, um, may need no testing

39:28

or you might want to, uh, in the, uh, acute setting.

39:31

Um, or you may just do a calcium score if they're stable

39:34

and they're not acute settings.

39:35

And then you might think about, um, the distinction

39:38

between anatomy and function.

39:39

So anatomy being CTA

39:41

and function being usually nuclear

39:43

testing or treadmill testing.

39:44

So, um, those at intermediate risk get a little more complex

39:47

and then you'll see, um, at the highest risks, then you want

39:51

to think about just going right to the cath lab.

39:52

So there's some people that's probably inappropriate

39:55

to start with A CTA

39:56

because they're such high risk that you should just go right

39:58

to to invasive angiogram.

40:00

And these rules are always local,

40:01

they're always changing on base, what on your availability.

40:03

And then each patient has, uh, unique data.

40:06

But the, this, the data that informs that little, um, set

40:11

of guidelines is massive.

40:13

And coronary CT angiography is the only class one

40:16

non-invasive test with level A evidence for diagnosing,

40:19

atherosclerosis and guiding treatment.

40:20

That's a really powerful statement I just made.

40:22

So there's really tons of trials.

40:25

Um, I've shown you just a few of them,

40:27

and there's many more that inform that.

40:29

So the coronary CTA allows you

40:31

to take decisive informed action.

40:33

You're gonna read based on cataracts,

40:35

and that's gonna match up to recommendations for management.

40:37

Um, let's change gears for one minute

40:40

and talk about cabbage cases.

40:41

So how do you do those? Well, um, you know, you can do it.

40:45

Uh, I just thought this is a really cool, um, study,

40:48

just cutting edge, but, uh, not how we should practice.

40:50

But they actually did coronary CTAs

40:53

before cabbage, uh, angiograms, um, to look at redo cabbage.

40:57

And they showed, uh, shorter procedures,

41:00

better satisfaction, lower rates of,

41:02

we don't cause nephropathy, you know this in the CT world,

41:05

but in the invasive cath lab, they do

41:07

because it's arterial contrast.

41:08

So lower rates of nephropathy

41:10

as associated with the angiogram.

41:11

Um, so really a cool thing.

41:13

Uh, and if it's negative, you may not need to do the, uh,

41:16

uh, cath in the first place

41:17

so you can geek out on all the different, um, you know,

41:21

nuances of how you do a calf.

41:22

But a CTA

41:24

before a calf actually lets you reduce the C duration.

41:27

We see the same thing with chronic total

41:29

occlusions in the angiogram lab.

41:31

So there's definitely edited value.

41:33

Um, we don't worry

41:34

as much about the native arteries

41:35

when we're reading those CTAs.

41:36

You're just looking at the bypass graft patent,

41:38

and you're gonna look at the, the anastomosis

41:41

and you're gonna look at, um, the graft in their course.

41:44

So very, in the course,

41:45

we've talked about tons of these, so I won't belabor that.

41:47

So cabbage, um,

41:49

and looking at grafts, great use for CTA.

41:52

Hey, what about stents?

41:54

Um, should I scan this patient with known stents?

41:56

Um, well, I used to say, um, much less frequent.

42:01

And now that some sites are getting these photon counting

42:05

cts, the, the rules are changing under our feet, literally.

42:09

So EID is energy integrating detector.

42:12

Um, that's the traditional CT that most scanners have.

42:15

Um, so the type of of, uh, photon count, uh,

42:18

photon attenuation, um, measurement, a here's a stent, uh,

42:22

in a, in a, uh, test tube, um, here is, uh, look at

42:25

that stent with an old style detector

42:27

and you can see that the, the lumen of the stent, um,

42:31

and the margin of the stent is big.

42:33

And then if you put that in a human with lots of calcium,

42:36

there can be lots of blooming.

42:38

So it can be very hard to look in this stent.

42:39

You can see how much wider

42:41

that the native artery in this model

42:42

appears above and below the stent.

42:44

Uh, they're all the same size,

42:47

but the the metal, um, takes up a lot more space.

42:51

And so we know that stents based on 2.5

42:54

or really three millimeters for those older scanners,

42:57

or our best bet, you're gonna need a good image quality.

42:59

There's caveats. If you have a really obese patient

43:01

or you have a very tachycardic patient,

43:03

may not be the test for you.

43:04

Now when you look at photon counting, detector scanners

43:07

and just early data here,

43:08

you can see we see the lumen so much better.

43:11

So now, um, the same stent, uh,

43:13

images far differently with a photon counter.

43:16

Um, and you can see this,

43:17

the stent strut width is a lot narrower.

43:20

Um, and so we see a lot more of it

43:21

and we've locally just recently gotten one.

43:25

So we still mostly use the older style.

43:27

Um, but the stented

43:28

and the really more importantly the calcified

43:30

or calcified an stented patients you can see better.

43:33

So it's a nuanced answer

43:34

because, um, if you're wanna look in a stent,

43:37

you're gonna wanna use that best scanner.

43:39

The other thing, um, we know is

43:41

that the non stented segments we're very good with, right?

43:44

That's the basis of everything else I've told you.

43:46

So if we are asked to look get stents,

43:48

we can certainly make sure we look at those native nons

43:50

stented arteries and clear them, um, just

43:53

to see an actual human CTA.

43:55

So here's, um, the still great scans both,

43:57

but here's the energy integrating detector.

44:00

Um, and uh, you can see that, you know,

44:02

there's only a small part of

44:04

that small vessel you see there,

44:06

this small branch look at the photon counter

44:08

and how much better you see the small vessel

44:09

and how much less blooming you see, um,

44:12

obscuring your lumen near the calcium in this LED.

44:15

So same patient, uh,

44:16

but a far better look with a photon counter.

44:19

So whether it's heavy calcium

44:21

or stents, I'm of course gonna prefer the image

44:23

on the right, if I can get it.

44:24

Um, okay, so pointers for stents.

44:27

Uh, do set expectations ahead of time.

44:29

If it's a small stent or you just think there's a low

44:32

likelihood of getting a good image, make sure

44:34

that the referring physician knows that.

44:36

Um, and tell them you're gonna focus on the non stented

44:39

and really the, the segments above

44:40

and um, below the stented artery,

44:42

those are very important clinically.

44:44

Um, do evaluate those native arteries.

44:46

Uh, you don't report calcium score. I I still acquire one.

44:49

We just do the same thing on everybody.

44:50

And sometimes you'll find a stent you didn't know you were

44:53

gonna find, and the non-con can help you there,

44:55

sort out dense calcium from stents.

44:57

Um, but you're not gonna score it

44:58

because those, that metal's gonna score really high

45:00

and there's no relevant database

45:03

to match the non stented vessels.

45:05

Um, this person has a sclerosis if they had a stent.

45:07

So you're probably, um, it, uh, reasonable, um, place

45:12

to give us, uh, preventive medicines no matter

45:14

what you see with a ct.

45:16

So it really becomes an exercise in looking

45:18

for obstruction either in the stent if you can see it,

45:20

or around the stent or in the

45:22

other vessels that aren't stented.

45:23

Um, don't expect an FFR ct.

45:26

We'll get to that in a moment,

45:27

but they can't do it right now.

45:29

Um, by FDA clearances.

45:31

Um, it will, depending on the, uh, vendor

45:33

and the uh, setting, um, do use your best scanner,

45:36

do follow up invasive angiography that result

45:38

because you'll be humbled at how difficult it is for us

45:41

to see the lumen and how well the, uh,

45:44

interventionalists can see the lumen.

45:46

Um, so I've kind of danced around it,

45:47

but what about C-T-F-F-R?

45:49

Uh, you've probably heard of it,

45:50

you've probably seen the marketing.

45:52

Um, so the problem with everything I've talked about

45:55

so far is that the extremes are easy, right?

45:57

Negative scan, negative predict value, we're great there.

46:00

Um, positive scan, it's pretty obvious what to do,

46:02

but sorting out

46:03

what happens in the gray zone here is difficult.

46:06

And the other dirty secret is we don't really have great,

46:09

um, standardization of what to use as a reference segment.

46:12

Um, or, um, what to do with bifurcations.

46:16

Um, what are normal sizes of arteries

46:18

and what about things that aren't just a simple one

46:20

dimensional stenosis.

46:21

You know, CTA was

46:23

before cath, we'd probably be looking at aerial narrowings

46:25

'cause that's, you know, flow is area times velocity.

46:27

Uh, but cath was first, they're two dimensional,

46:29

so we're bound to that 50% diameter narrowing paradigm.

46:33

But we, if anyone that does bone x-rays, no two views is,

46:35

you know, one view is no view.

46:36

So, um, you can have an oblique stenosis,

46:38

you can totally miss it if you just have

46:39

that one angiographic view.

46:42

Um, so how to solve these problems.

46:44

One way is to do, um,

46:46

fractional flow reserve calculated from

46:48

a computer tomography.

46:49

So you take the CT dataset, you do, um,

46:52

this is the first vendor's way of doing it,

46:54

it's computational fluid dynamics.

46:55

So they throw it in a supercomputer model,

46:57

just like a wind tunnel, um,

47:00

or a uh, uh, that kind of, uh, computation.

47:03

They do some assumptions about the blood viscosity

47:05

and how much myocardium needs supplied, uh,

47:08

in that exact patient.

47:09

And then they come out with a map

47:10

and they predict what the invasive

47:12

fractional flow reserve would show.

47:13

And there's similar thresholds.

47:15

So basically this 0.75 lesion is positive here.

47:18

It's a focal trans trans lesional gradient.

47:20

So this is a positive case.

47:22

Uh, and that comes from the base CTA, so you can, um,

47:25

there's different brand names,

47:26

but C-T-F-F-R is the most vendor agnostic.

47:29

So if you look at the SCCT guidelines recently published

47:32

as a multi societal, that's what we should be calling it.

47:35

Um, and in what I'm, what I believe is the best data set

47:40

and not as perfect, but there's a specific trial

47:42

where they did all the tests in everybody stable outpatients

47:45

of course, and they found that, um, the FFR CT

47:50

combined with, which is of course combined with the CTA,

47:52

had the best area under the curve

47:53

to predict obstructive disease.

47:55

So, um, you can see spec's, older technology doesn't do

47:58

as well, PET does very well.

48:00

Um, but C-T-F-F-R, um,

48:02

which inherently implies you have knowledge of the CTA, um,

48:06

had the strongest area under the curve.

48:08

So best accuracy, um, had all, we use it locally,

48:13

we look at it like a wingman.

48:14

Um, so we make an impression of the CT angiogram

48:17

and tell it like we see it without the FFR.

48:19

So this is an intermediate lesion.

48:21

I called, this is my exact words, CTA impression, uh,

48:25

CADRAD three, it's a moderate proximal L led D stenosis.

48:28

We sent it off for FFR ct, there's a focal drop,

48:30

it's very clearly below threshold.

48:32

So we said, Hey, the lesion of concern

48:34

that's we weren't really sure of with our own eyes, um,

48:37

comes back as clearly significant by CT FFR.

48:41

He went to the cath lab, found the same thing, stented,

48:44

they, uh, did an FFR invasively,

48:46

it was positive, patient got better.

48:47

So we treat the right disease here.

48:49

But if, if I looked at this, I'm like,

48:51

eh, it's kind of middling.

48:52

It's not the difficult to predict

48:54

what the hemodynamics will be.

48:56

Um, just so that's one anecdote, but how does it work?

48:59

Well, we looked at, this is pandemic times.

49:01

The volumes are way higher. Now.

49:02

I think we're gonna do 15,000 coronary CTAs this year.

49:05

But anyway, 3000 CTAs.

49:07

Um, can't do cabbages, can't do stents, whatever.

49:11

Um, uh, if the stents in the other side of the heart maybe,

49:13

but, uh, preponderance are outpatients slightly,

49:16

but we do inpatients and emergency patients.

49:18

Um, we decide who gets A-C-T-F-F-R referral based on reader.

49:23

If one of our referring physicians really wants it,

49:25

we'll indulge, but the reader should be the one

49:27

to know whether they need the help.

49:29

Um, a tiny fraction weren't assessed.

49:31

So about, you know, of the 3000, about 10%

49:34

or less, uh, go to FFR

49:36

and the majority of those are negative,

49:38

whether they're in or outpatient.

49:40

So, um, basically C-T-F-F-R greater than point

49:43

A is very clearly negative.

49:44

And then this gray zone where it's kind of on the upper end

49:47

of the gray zone, we, they tend to be less concerning.

49:50

Um, and so those are kind of triaging the disease downward.

49:54

Now, what kind of disease did we send?

49:55

Well, here's our CADRAD score.

49:57

So occasionally we're sending a

49:58

five 'cause there's some other vessel.

50:00

Um, this is a, uh, the cataracts three tends

50:03

to be the main use case.

50:05

So obviously we only send a few of the clearly severe ones.

50:09

And then, um, ev every once in a while you send something

50:12

with mild disease just 'cause it looks funny

50:14

or the referring ones, it's so fine.

50:16

Um, we do two reports.

50:18

We, we don't know for sure the FFR will be successful,

50:20

but, uh, some vendors will sell you, Hey,

50:23

send us all your cases and you pay if you click.

50:25

Um, I don't know how we sustain the world that way,

50:28

but, um, that's what they're offering.

50:30

Um, and you know,

50:31

you could have two different reporting physicians.

50:33

We like to keep it in, in the initial reader's queue.

50:37

Um, also people

50:38

with like these mild distal abnormalities, they don't work out.

50:41

You wanna look for a focal lesion.

50:42

There's good, um, literature on this. This is the paper.

50:46

Um, so you wanna look for, um, uh, look for a distal value

50:51

that's clearly significant beyond a focal stenosis.

50:54

So look for about two centimes beyond it for a drop of,

50:57

you know, 0.15 or so.

51:00

Um, the, uh, that fits into the, uh,

51:05

guidelines, the, the chest pain guidelines that I show you

51:07

that if you have it, you might find that, um,

51:10

where they say stress test is appropriate,

51:12

if it's native arteries, uh, C-T-F-F-R, uh,

51:15

is a potentially appropriate.

51:17

Um, what about plaque analysis?

51:18

I'm seeing so much of this, uh, hearing podcast

51:21

and pop literature talk about it.

51:23

Um, these are all the same knots that I gave you for A CTA

51:26

or a calcium score, which is

51:28

you're not doing it, have a look.

51:29

You're not doing it 'cause you heard, you know, a podcaster

51:33

or a, uh, bestselling author say you need it.

51:36

Um, not because the marketing company uh, comes to you

51:39

and says that you need one.

51:40

Um, you don't come do plaque analysis

51:43

if it's not gonna change management.

51:44

And that's where we're still struggling

51:45

to find exactly when we're gonna change management

51:47

and not if there's a more appropriate test.

51:48

So if you're, you know, if, if it's going to the cath lab,

51:51

it's probably better to do the plaque analysis there.

51:53

This is one vendor's analysis on a patient we had.

51:56

I just wanna show how you have, um, you know,

51:59

they're giving you the breakdowns of what's calcified,

52:01

what's noncalcified, what's very low density.

52:03

Um, and so those things may be informative

52:05

and help you follow them over time.

52:07

Or what I suspect I'm just speculating, is

52:10

that once these expensive therapies are out there,

52:13

like PCSK nine inhibitors, um, probably need

52:16

to do some kind of a selection.

52:17

And I'm not aware of any, um, anybody doing that now,

52:20

but would be a good way

52:21

to gatekeep is see who's at highest risk, uh,

52:24

by looking for their plaque scores.

52:26

Uh, and then I wanted to speculate for just a moment

52:28

before we open it up for questions.

52:29

What do I think the future of CTA will look like?

52:31

Well, um, this is a cool paper from a colleague of mine, Mar

52:35

Ari, um, where they use radios, um,

52:38

and they could distinguish patients with atherosclerosis,

52:41

um, and tell whether the atherosclerosis was from cocaine

52:44

use from just traditional risk factors

52:47

or from HIV infection or some combo.

52:49

So I can't tell what's causing the plaque.

52:51

I'm not that, um, much of a pattern recognizer,

52:54

but the supercomputer is,

52:55

and they fairly very clearly based on radio mic features,

52:58

which we don't even know what we're looking at, um,

53:00

they can distinguish types of disease.

53:02

So maybe that has some, um, patient benefits.

53:05

Um, so they, they found structural features that I,

53:08

I certainly can identify, um, between cocaine

53:10

and HIV related plaque.

53:12

Um, and, and then maybe more useful would be, um, uh,

53:16

sorting out, uh, well, this one actually is cool,

53:18

so I'd try, men

53:19

and women tend to have slightly

53:20

different sub patterns of disease.

53:22

Um, older patients

53:23

and younger patients broke down differently.

53:25

Um, and so interesting, um,

53:28

to support a distinguished sex stent age.

53:30

Um, but, but this, what I thought was really cool is

53:32

the unstable plaques.

53:33

So those patients in the ER might have multiple stenosis.

53:37

What's the one we should go after first?

53:38

Or what's the one that I should send electively

53:40

first to prevent disease?

53:41

And we don't do preventive stend right now,

53:43

but uh, maybe this gets us there.

53:45

Um, so it's early days,

53:46

but radios sounds like a, a pretty cool, um, way to do that

53:50

and add a kind of a, uh, really good, um,

53:55

cyborg like future to, to my brain that would make,

53:57

uh, me a more accurate reader.

53:58

Um, so anyway, we talked about kind of trends

54:01

and basics of CTA,

54:02

but we talked about, uh, how it's becoming mainstream, um,

54:06

how population level data is there.

54:08

Um, how I, I didn't get into much,

54:10

but I think the democratization

54:12

of CT is only just beginning.

54:13

Um, like I said, our sites volume has gone up

54:17

amazingly in the last few years.

54:19

Post pandemic, um, guidelines are accepting it.

54:22

There's gonna be some screening rules.

54:24

Um, we're gonna make everything more efficient and,

54:27

and, uh, do more of it.

54:28

So be ready. Um,

54:30

and I'm sure you already are encountering

54:31

what we're encountering and then I think the post-processing

54:34

is gonna really help us cope with these things.

54:36

So, uh, I'll call it the era of big recon,

54:38

whether it's F-F-R-C-T

54:40

or whether it's um, uh, augmented radios.

54:44

Um, but I thought it might be a great time to, um,

54:48

take some questions.

54:50

So, oh, we have a QA here and a chat.

54:52

Let's see if anyone knows. Um, okay, here we go.

54:58

So how, okay, I'll let just go in order here.

55:02

How, um, does, do you usually set your window width

55:05

and level for evaluating stented images?

55:07

Answer very carefully.

55:08

Um, I want to see, you don't want it so white

55:12

that you can't distinguish, um, contrast from calcium

55:15

from, uh, stent.

55:17

And so it's impossible for me

55:19

to tell you, uh, an exact number.

55:21

The dynamic range of the scan changes based on the patient's

55:24

size, the KV selected, which could vary, um,

55:27

and the amount of contrast enhancement you have.

55:30

So, um, I would say, um, the glib answer is very carefully.

55:36

The more real answer is windows,

55:38

so you can distinguish those.

55:39

Um, and it's gonna, you know, gotta go up

55:41

and down until you see a distinction between, um, those, uh,

55:45

those boundaries if you're lucky.

55:47

Um, second question is treating stent like a cabbage?

55:51

Don't look at native vessels.

55:53

Uh, I do look at the native vessels, um, on the cabbage,

55:57

but only when they're not revascularized.

56:00

So say you have a left main occlusion, um,

56:02

and you have a, a, a lima bypass, well,

56:04

I'm not worried about that le uh, left main or proximal LED,

56:07

but I am gonna worry about the distal.

56:09

Um, and, uh, uh, so you may want to,

56:12

you're not gonna spend all day quantitating.

56:14

What's obstructed? Um, by the way, when you apply cadrad,

56:17

you wanna say, hey, um, assuming that the, um,

56:21

vessels bypassed, uh, you don't hold that worst stenosis

56:25

unless it's, it's unprotected.

56:27

Meaning say you have, um, a lima bypass graft to the LAD

56:31

and its patent, but you have a new RCA severe stenosis in

56:34

your non revascularized RCA, that would get you

56:38

to at least a cataracts foray with a modifier for graft.

56:41

Or, um, hopefully that answered your question.

56:45

Um, and oh, or should we look at the native vessels

56:47

because of new disease?

56:49

Um, yeah, actually exactly that.

56:51

Do the best you can with a stent, um,

56:53

and then be really nice to administrators.

56:55

Maybe it'll get you a better scanner if you have trouble.

56:57

Um, and exactly that's the next question here is main role

57:00

of photon counting CT and CTA.

57:03

It's gonna be for stents

57:05

and really heavily diseased patients.

57:07

I, um, I work at Mass General.

57:10

We have 13 sites, uh, I think, no, sorry,

57:14

I live in sites 13 scanners

57:15

and we're kind of in, uh,

57:19

gradual marriage with Brigham and women.

57:20

So I guess you just up those numbers, just a touch.

57:22

But we only have a couple of photon counters

57:25

and you can't do all your patients.

57:26

We're doing 80 coronary, 80 cardiac CT day a day,

57:29

the majority of which are coronary you.

57:31

Not everyone can fit on the, um,

57:33

photon counting scanner we just opened up.

57:36

So probably the best way to select for

57:38

that is if you know they have a stent

57:39

or maybe it's a cabbage, maybe it's your TAVR patients,

57:41

we clear them on all the, um, ooh.

57:44

Uh, another, um, question here.

57:46

Is there really beneficial to give, um, tablets?

57:49

So I think you were asking for, um, uh, an just said,

57:52

but maybe, um, nitroglycerin?

57:54

Yes. Um, I've tested it myself

57:57

and it's a randomized controlled trial.

57:58

You can look me up, but it's in, uh, JAK imaging.

58:01

A few years back we tr tested nitroglycerin, um, pills,

58:05

patches, and sprays, and we looked at the before and the

58:08

after, um, they, uh,

58:10

the nitroglycerin dilates you about 17%.

58:13

Um, it's preferred if you can get it.

58:16

And it also helps you, um, not under call disease

58:18

because the disease, the atherosclerotic artery, um,

58:22

won't dilate whereas the native should, um,

58:24

and it's alleged to make your F-F-R-C-T more accurate.

58:28

So, um, if you can do it, give nitroglycerin,

58:30

we use patches when we can

58:31

because it keeps us outta the room

58:33

and the nurses apply it for it.

58:35

Um, is there any role for Aden in use in F-F-R-C-T?

58:38

Great question. I'm not aware of that.

58:40

Um, nitroglycerin, they prefer you use it if you can.

58:43

Um, though we do get away

58:44

with it in TAVR patients where it's contraindicated.

58:47

Um, let's see.

58:48

What method do you use in practice

58:50

for interpretation of ct ctm?

58:51

It's recon images for axial versus vessel walkthrough.

58:54

If you look at my course, we go through this a lot.

58:56

Um, I'm a purist, so I'm gonna start with axials,

58:59

but then always do another plane,

59:00

especially for the left main.

59:01

You can miss left main diseases.

59:02

You don't look at all two views.

59:04

Um, we use, um, uh, multiplanar reformative images

59:08

and then we have a 3D lab, um,

59:10

and they make multiplanar reformats with curves.

59:13

The danger there is if the, uh,

59:14

the center line's off, you can get into trouble.

59:16

So always wanna look at at least two.

59:18

Um, there's a great paper by Mars Forensic who succeeded me

59:21

as president of FF of A, uh, the Society

59:24

of Cardiac CT showing the fundamentals

59:27

and multiplanar reformative images are better than axials.

59:29

That's a proven known.

59:31

Um, do I have any articles regarding photon counting ct?

59:35

Not yet. Personally. I just got it.

59:36

So I'm just having fun geeking out with it.

59:38

But there are a lot. Um, I would say they're early

59:42

and they're very technical right now.

59:43

Um, but PubMed should be a great, uh, adjunct for that.

59:47

Um, nitro spay is the spray is the best facets at what time

59:51

spray in pills have to be given.

59:52

Ideally within three to five minutes of the, uh, scan

59:55

patches can be done.

59:57

You wanna do it a little early, you wanna do it 40 minutes.

59:59

So we do it early and let it kind of, I call it marinating,

60:02

but just let that, uh, take effect.

60:03

Uh, if you do an nitro spray, you need

60:05

to know it wears off within 10 minutes.

60:07

So you wanna redose it if something goes wrong.

60:09

What's the best scan time?

60:11

I'm assuming that's a related, uh, time.

60:12

Oh yeah, so we than five minutes.

60:15

We'll, CT profusion suppress MRII kind of hope it does

60:19

'cause the MRIs are hard, but in reality, um, the, we'll see

60:23

what photon counting brings, but tissue contrast, uh,

60:26

as far it's like five times, uh, better with MR than ct.

60:30

So, um, for now, uh, r Profusions probably the way you want

60:33

to go if you can get it.

60:35

Um, but it kind of is nice to have ct.

60:37

I written some papers about it

60:38

and it's, it's a very appealing to be able

60:40

to get everything in one, one stop shop.

60:42

So, uh, and Melissa, thank you for your, uh, uh,

60:45

and hello to the residents.

60:46

You picked the right field. Um, thank you for the, uh,

60:49

um, uh, feedback.

60:51

Any other, uh, oh, I see the same question was in the,

60:56

um, chat as well.

60:57

I think you, I think you answered all the questions. Dr.

61:00

Kra, excellent job.

61:03

Thank you so much for sharing your lecture with us today

61:05

and taking the time to answer questions.

61:08

Thank you so much. Spectral CT gonna be similar to Photon.

61:11

I think it's cool, uh, new technology,

61:13

but thanks for all the questions and uh, I'll,

61:15

uh, let you take it from here.

61:17

Alright, and thank you to everyone

61:19

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61:21

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61:23

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61:26

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61:27

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61:30

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61:35

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61:37

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61:40

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61:43

Density Insights and Cases from Past, present, and Future.

61:47

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61:51

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61:54

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61:55

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61:57

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