- So what is a PET scan analogous to?
If you can imagine injecting tiny little light bulbs that go
to a patient's heart, and then the camera is measuring
at what light is coming out
and creating a picture from that light.
That's about as close as I could come to any type
of analogy, but what I just described clearly, isn't real.
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- So nuclear imaging from a cardiovascular perspective
is a noninvasive technique where we're able
to look at various aspects of the heart,
whether it be function or flow,
a variety of different components of the heart
using nuclear materials that are injected
into the bloodstream.
They're safe, they're quickly expelled
but they provide unique information
about the heart and the heart function.
Nuclear imaging and cardiology evolved alongside each other
throughout the 1900s.
Their paths gradually interweaving as our knowledge
of both feels broadened until the two were united
through the modern advancements in technology.
We've been looking into the human body
for over a hundred years, but how did we get there?
November the 8th, 1895, x-rays are discovered
by German physicist Wilhem Renkin.
He takes the first x-ray image
showing the skeletal structure of his wife's left hand.
1911, the first practical application of a radio isotope
used by George de Hevesy.
1924, the American Heart Association is formed.
1929, the first right heart catheterization is performed
by Werner Forssmann, on himself.
Later, 1950s, Framingham Heart Study
identifies saturated fat as a cause of heart disease.
First attempts at urging Americans to change their diets
for better heart health.
October 30th, 1958, first coronary angiogram
is accidentally performed by Cardiologist F Mason Sones.
1960s, first usages of endoscopes and bypass surgery.
1973, first myocardial stress perfusion imaging
is performed using potassium 43 radioactive tracers.
1974, the first PET camera is developed.
1980s, first use of stents and MRI scanners are installed
in hospitals.
2000, Time magazine names the PET CT scanner
the medical invention of the year.
- PET is an acronym for positron emission tomography.
And it's a fancy way of saying, taking pictures
using positrons.
So the obvious question is, what is a positron?
So a positron is a certain type of particle
that's the size of an electron,
but has an actual opposite charge of an electron.
And positrons have a strange and unique property
that when they run into an electron, both the electron
and the positron vanish.
Their mass disappears and the energy is released
in a straight line, 180 degrees apart.
So, what we do is, we take a camera
that can identify these energy waves that come across
and we put the camera around the person.
- The PET camera looks a lot like a CT scanner
or an MRI machine in that the patient lies
on a gantry and is encircled by the camera.
So the camera goes 360 degrees around the patient.
And as these positrons leave the patient's body,
they're hitting the PET camera all around the patient.
And that enables us to collect the data or the information
from the patient's heart.
- Because we are able to not only take pictures of where
that radioactive material went to in the heart
but we can measure numbers of how quickly it got there,
we're able to really put together a treatment plan,
really even without knowing
what's going on with the patient.
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So we're now in our reading room,
which is where all of the images,
after the camera has acquired them
and processed all the data.
All of that data and images are sent into this area
where we can pull everything up on monitors
and make our clinical interpretation and do our reports.
The way that we do it is we inject the radio tracer,
which is like little light bulbs that go inside
and then shine the light and then our camera measures all
of that light and what the camera and computer systems
will do is now take all of those light beams
that were emitted and it's gonna make an image of a heart.
We measure not only where the light comes out of the heart,
okay, but how fast it's doing so
and that's where things become very complicated.
And that's really where the power of PET is,
where we can measure the the speed of the blood moving
through the heart itself.
So, this is an example of a normal study
and you can see there's no chunks of green or blue
or any dark splotches.
Everything is nice and uniform and it looks pretty.
But as we look at some abnormal studies,
we want to focus on when there's blue capacity,
that's when really stents and bypass surgeries really help.
When there's no blue, you're not seeing a benefit
with bypass and stents from a mortality standpoint.
You're not seeing a reduction in heart attacks
if you're doing procedures when there's no blue.
So this is another example of a patient
who, actually, for other reasons, had an angiogram
and it was recommended that he actually have bypass surgery
and the patient really felt well and questioned the need
for bypass and ended up coming to us to get a PET scan
to determine really if the bypass was necessary.
- I was running a 5k and noticed that I was short of breath
after about a mile which is a little unusual,
but thought, well, I'm getting older,
not as good a shape as I used to be.
I had my annual check up with my primary care physician.
Told him about these instances
and he said, well, why don't we do a stress test?
The stress test revealed what they call a left bundle block.
After receiving an angiogram, I was suggested
to have bypass surgery.
- When a patient goes for an angiogram,
we're basically getting an anatomic assessment
meaning we're able to see that patient's arteries
and if there's plaque in there
or if there's blockage in there.
But what we don't know is if that blockage
is causing a problem.
Is it causing that patient's heart
to get an inadequate amount of blood flow?
And one thing we know is that we're notoriously bad
at being able to judge which blockages are significant
on an angiogram and which are not.
And this is where the PET stress can help us
because it's giving us a physiologic assessment
of those blockages in an individual patient
and allows us to determine, is that a blockage
that needs a mechanical revascularization or not?
- I received a call from my cardiologist saying, look
you don't need bypass surgery
and the relief of hearing those words was incredible.
- You know, I kind of joke,
I say for your first 18 or 20 years, do whatever you want,
enjoy the fried chicken, enjoy your cow.
And then after that, you really have to focus
on risk factors and lifestyle.
The vast majority of coronary disease and diabetes
and hypertension and high cholesterol can actually
be prevented by just good lifestyle.
As we age, I think we should be moving
into a plant-based diet.
And when that isn't good enough, we start adding medicines.
- The way that it was explained to me is,
look, you've got blockage.
Most of us have blockage.
It's the flow which is critical.
If I got serious about my diet and exercising,
that this would be the best treatment for me.
- As a former interventionalist, I can say
that using PET stress in my own practice
has really changed how I treat my patients.
I was used to revascularizing or stenting, really
any type blockages that we saw on a coronary angiogram.
And what I've now found is that with the information
from the PET stress, I'm stenting much fewer patients
and really getting excellent results just
with medical therapy and lifestyle changes.
- People don't realize this, but you can actually
unclog arteries just by your diet and exercise.
So these are things that we never thought were possible.
And oddly enough, the reversal studies,
showing reversal of coronary disease,
the initial studies were done using PET scans.
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