When you think about looking inside your own body, you may only be able to picture
images like this or this.
But an emerging technique gives us pictures that look like this...using laser-induced
sound waves.
Early technologies that use this technique seem to provide us with highly detailed, super
clear images of the structures inside our bodies...with no discomfort or dangerous ionizing
radiation involved.
This promising technique is called photoacoustic imaging.
A basic breakdown goes like this:
Different biological materials have different chemical structures.
The hemoglobin in your blood, for example, is chemically different from the calcium in
your bones, and this means that they’re able to absorb different amounts of energy.
Photoacoustic imaging takes advantage of these differences in composition by tuning laser
light to the wavelength that can be absorbed by the tissue you want to look at.
So an apparatus sends tuned pulses of laser light to a specimen or body part
and the tissue that can absorb that wavelength of
light absorbs that energy...and heats up.
And when the tissue heats up, it expands ever so slightly.
That expansion and then rapid cooling generates a wave of oscillating pressure in the surrounding
material: the rest of your body or the air...which is, in the simplest possible interpretation,
a sound wave—that’s the ‘acoustic’ part of the name, giving us ‘photoacoustic
imaging’.
Then, ultrasonic detectors capture these microscopic changes in pressure and processing software
reconstructs an image based on what those sensors "hear".
It’s pretty different from other current imaging technologies.
CT scans and X-rays and PET scans use damaging ionizing radiation to see inside your body,
so we want to limit how many times we expose someone to that radiation.
An MRI involves an extremely strong magnetic field, which can be a problem for anyone with
any kind of metal implants, and they often take many minutes to form an image.
Even ultrasounds, which also use sound waves, actually aren’t as clear as this newer option.
Ultrasounds are more of a catch-all: you see everything, all the tissues in a specific
area, whereas with photoacoustic imaging, you can pick and choose what you want to see
just by tuning the wavelength of the laser beam.
And while this technique is only just starting to be clinically explored as an alternative
to more traditional imaging and prototype clinical machinery is just now being developed,
the idea has actually been around for more than a century.
Alexander Graham Bell—you know, the guy who invented the telephone?—was the first
to observe that electromagnetic waves could induce sound waves when applied to materials.
But the technology that’s started to emerge and be refined in just the last decade takes
that initial observation and makes it into something that could seriously revolutionize medicine.
Imaging veins and arteries this way, for example, can tell us more than ever before about changes
in someone’s circulation, or abnormalities in blood flow related to cardiovascular diseases.
We can see how tissues are faring after surgeries, we can see what kind of effect a drug is having...the
applications are really kind of stunning when you start to think about them all.
Because not only can this technology be used to image tissues at extremely high resolution.
You can also introduce a foreign material, like a contrast dye or a specially designed
nanoparticle, to see things you might not be able to otherwise.
These substances can be tailor-made to bind to certain kinds of cancer cells or other
forms of gene expression.
And then you can tune the laser to the wavelength absorbed by that contrast or nanoparticle,
giving you an extremely detailed and accurate pictures of how a disease manifests in your
body.
And I guarantee you’re not ready for what’s maybe the coolest part: there are several
companies that are making versions of this technology that’s highly portable, and are
designing software that uses machine learning to identify different structures on the image
for the user.
Both of these developments mean it’s possible that some patients could use this technology
themselves to monitor their own health and things like progress during recovery from
a condition or a surgery.
Technologies like this are an exciting look into how we’re improving our understanding
of our own bodies and the way we can look at and treat them.
I love how physics and engineering and computer science and medicine are all coming together
to make this happen, I think it’s a great example of how big leaps in science are, by
necessity, cross-disciplinary collaborations that, by the sound of it, will continue to
improve lives all over the world.
If you want even more on new and improved ways that we can monitor our own health, check
out this video here, and make sure you subscribe to Seeker for all your medical innovation news.
If you have another emerging medical technology you’d like to see us cover, let us know
down in the comments and as always, thank you so much for watching and we’ll see you next time.