0:00

So let's just start off with, uh,

0:02

some basic anatomy review.

0:03

Each of these will be a real case,

0:04

but we'll just kind of go back and forth.

0:06

Here's a 56-year-old woman

0:08

with new onset atypical chest pain.

0:10

And this is one of the first parts of the way

0:13

that we do a cardiac ct.

0:14

And you don't have to do a coronary CT with, uh,

0:17

specific protocols, but we find

0:19

that being comprehensive helps.

0:20

So, um, this is the axial dataset from

0:24

a calcium scoring scan.

0:25

Uh, and as you know, that's not enough

0:26

to call it a coronary ct.

0:28

Uh, but you can see here we've conned down on the chest.

0:31

So we've maximized our space over resolution.

0:33

We have motion free images,

0:34

and we're looking at the aortic root.

0:35

And you can see my cursor circling the

0:38

right coronary artery.

0:39

Uh, the right coronary artery is the most likely

0:41

to suffer from motion artifacts, but we don't see that here.

0:43

I also don't see any calcified plaque.

0:45

You can tell calcium because it would

0:47

be the density of bone.

0:48

Let's look at the left system here.

0:49

So there's a left main

0:51

or LAD, left anterior

0:52

descending, moving to the anterior side.

0:54

And as it plays one more time, we'll try

0:56

to follow the circumflex, which is probably non-dominant

0:58

as it usually is, and lives here.

1:01

So that's a nice look at the anatomy on a non-contrast ct.

1:04

But what makes things a lot easier is to look

1:06

through contrast, uh, ct.

1:08

So this is a different patient, uh,

1:10

and this is, uh, a gentleman with chest pain

1:13

and he'd actually been into an emergency department, so

1:16

not known disease, but um, soon to be a known disease.

1:19

Um, and you can see there's a lot more slices here

1:21

and that helps us sort out anatomy.

1:23

This is the, uh, ascending aorta.

1:25

This is the pulmonary artery,

1:27

and I'm just gonna, uh,

1:28

focus your eye on the right coronary artery.

1:30

Here's the left, uh, and some plaque.

1:33

Um, but as you can see, we'll, we'll kind

1:35

of watch the right coronary artery as it scrolls down.

1:38

Again, many finer cuts

1:40

and obviously a little cumbersome to look through.

1:42

Just source axial data.

1:44

So there's your right coronary artery

1:45

and we already see some plaque and start to lose the vessel.

1:48

You can also look in here

1:49

and see the left anterior descending,

1:51

some diagonal branches,

1:52

and then the obtuse marginal branch

1:54

of the circumflex artery.

1:56

So, um, we've kind

1:57

of honed our eye on the right coronary artery

1:59

because that's the anatomy of interest

2:01

as you're about to find out.

2:02

Now, when we do these studies, um, it's important

2:05

to look at the source axial data.

2:07

Know that you have high quality data sets,

2:09

and I know there's some other courses that have already

2:10

touched on the basics of coronary ct,

2:12

including one by Dr. Zimmerman.

2:14

And so you could refer to

2:15

that if you're still catching up on, um, how to perform it

2:18

and reformat the ct.

2:20

Uh, I'm gonna now show you how we reformat this case,

2:23

and we'll do this at the workstations in a few minutes.

2:26

But here's that right coronary artery as we spin around it.

2:29

And you can see here this is the right coronary artery

2:31

living in the atrial ventricular groove.

2:33

Um, and this is something that's, um,

2:35

sharpening into the C view, which is a, a view

2:38

that looks like the letter C and it in the cath lab.

2:40

That's the way that the anatomy is displayed.

2:42

And so you can see here a stenosis.

2:44

This is called a multiplanar reformatted image, NPR, uh,

2:48

and it's important to lay out the vessel in the long axis.

2:51

'cause in anyone's, uh, axial slice

2:53

or anyone's short axis slice, it's hard to discern whether

2:56

or not there's a stenosis. Um,

2:58

And then once you've decided whether you think it's a

3:01

significant or not stenosis,

3:02

you'll fit things into boxes here.

3:04

This is the CAD rads, uh, paradigm.

3:06

So it's a reporting and data system,

3:08

multi societal, uh, support.

3:10

Uh, and these are now curved plane reformative views.

3:13

So, uh, this now lays the same vessel out in

3:16

a one single slice.

3:17

In long axis, you would have to spin it

3:19

to see the entire vessel, but, uh,

3:21

we're gonna now decide on stenosis grading.

3:22

So it's no plaque, no stenosis,

3:25

that'll be cadrad zero if there's atherosclerotic plaque,

3:28

but only minimal stenosis, uh, that's cadrad one.

3:31

So maybe up to 20, so percent, 25%.

3:33

Uh, the exact percentage of the grading doesn't matter

3:36

as much as what you think it'll be physiologically.

3:38

So cadrad two, again, it's just mild,

3:40

so nothing even over 50% stenosis.

3:43

Um, here's a CT angiogram with plaque,

3:45

and you can see that dense calcified plaque, plaque blooms.

3:48

So it looks a little bigger, uh, especially relative

3:51

to a small, uh, coronary lumen.

3:53

Depending on your technology, it has more blooming or less,

3:56

but that's, uh, very apparent by ct.

3:59

Less apparent by invasive angiogram.

4:01

In fact, uh, we know

4:02

that the CT scanner can show us

4:04

10,000 densities more than a human.

4:05

I can see we have to window width

4:07

and level to display what we can look at,

4:08

whereas in the Lumino Graham that you get in the cath lab,

4:11

it's basically five densities.

4:12

And here we're really just looking at the lumen of

4:14

that same vessel, um,

4:15

and looking at the degree of narrowing.

4:17

So when you read a cardiac CT

4:18

or you look at the anatomy, you want to think

4:20

that you're probably over representing the calcified plaque,

4:23

um, and that you are, uh, seeing much more the things

4:27

that cause the luminal narrowing, uh,

4:29

than the invasive angiogram that might result.

4:31

And then of course, there's intermediate stenosis, kind

4:34

of a 50, less than 70%, uh, stenosis Here, it's hard

4:37

to say the physiologic significance.

4:39

There's the angiogram.

4:41

Cadres four is the severe stenosis,

4:42

and that's the case I just showed you.

4:44

This is the right coronary artery laid

4:45

out in a long axis view.

4:46

A curved plane, a reformat view, there's a matched cath.

4:50

One last thing to remember when you're looking at normal

4:52

anatomy is that the, the basis of ct, which really happens

4:56

before you have known cad, is

4:58

that the negative predictive value is the sweet spot.

5:00

Meaning if the CT is negative, no further workup needed.

5:03

And that requires looking at all of the coronary segments.

5:06

So this is just a stripped out volume rendered view.

5:08

And what you're seeing here is the aortic root.

5:10

You're seeing the right coronary artery

5:12

where we saw the stenosis in the last patient.

5:13

Different patient, of course, this is the left main,

5:16

the left anterior descending got diagonal branches

5:19

coming off perpendicularly.

5:20

And then towards the septum you'd have small septal

5:22

perforators, circumflex artery, usually non-dominant.

5:25

And that has OBT two marginal branches.

5:27

So in order to call a CT negative, you have

5:29

to have seen every single vessel segment

5:31

and seen that there's no stenosis.

5:33

Now the focus of this course will be much more in the

5:35

setting of known coronary disease, so either higher risk

5:38

or people where we already know that there is stenosis

5:40

and we need to work it up, or we're looking at complications

5:43

of said stenosis.