JUN 03, 2017 6:45 AM PDT

Can You Hear that Laser Beam: a New Photoacoustic Imaging Technique that Explores Anatomy and Physiology with High Spatiotemporal Resolution

Can you imagine pointing a flash light toward a cave and hearing the echo from within? No? The analogy appears absurd, but photoacoustic effect is real. It describes the occurrence of sound, or more accurately sound waves caused by the absorption of photonic energy. Photoacoustic tomography (PAT) is an imaging method that applies such phenomenon to examine anatomic structures and even physiological functions in biomedical research.

You might wonder how this imaging modality is compared to the ones that are already used routinely in the clinics. To generate images, X-ray, CT, SPECT (single photon emission computed tomography) and PET (positron emission tomography) all rely on a source of ionizing radiation, either external or internalized one. MRI (magnetic resonance imaging) requires strong magnetic field and radio waves, the monetary and time cost could easily add up. Compared to ultrasonic imaging, PAT has better optical contrasts and is free of speckle – noise caused by sound wave scattering. Finally, unlike other purely optical-based imaging techniques that are under development, PAT can penetrate deeper and sustain high spatial resolution.

Related reading: Photoacoustic tomography

Now the PAT family has a new member, which is designed to take the technique to a whole new level. According to an article recently published on Nature Biomedical Engineering, a new technique called single impulse panoramic-photoacoustic computed tomography (SIP-PACT) was developed by a team of researchers from Duke University and Caltech. It did a lot to improve upon the current PAT, and achieved several outstanding qualities: high spatiotemporal resolution, deep tissue penetration, multiple contrasts, and full-view fidelity.

The imaging device consists of a short-pulse laser as light source and a ring-shaped detector made from 512 ultrasonic transducer elements. To investigate the oxygenation status of hemoglobin and hemodynamics through the body, the authors used a head-focused and a whole-body tomographic slicing illumination scheme respectively. Thanks to the excellent performance of SIP-PACT, the joint research team not only captured real time images/videos of hemodynamic of small animals with exquisite detail of anatomic structures and physiological changes, but also tracked down circulating melanoma cells in the rat brains without any labeling.

“This penetration range enables functional imaging of whole bodies of small animals. It is expected to enable all kinds of biological studies in small animals and to accelerate drug discovery,” said the corresponding author of the paper Lihong Wang, who is a PAT pioneer of Caltech.

Article title image: an SIP-PACT cross section image of a rat's torso. Credit: Lihong Wang

Source: Optics.org 

About the Author
  • Graduated with a bachelor degree in Pharmaceutical Science and a master degree in neuropharmacology, Daniel is a radiopharmaceutical and radiobiology expert based in Ottawa, Canada. With years of experience in biomedical R&D, Daniel is very into writing. He is constantly fascinated by what's happening in the world of science. He hopes to capture the public's interest and promote scientific literacy with his trending news articles. The recurring topics in his Chemistry & Physics trending news section include alternative energy, material science, theoretical physics, medical imaging, and green chemistry.
You May Also Like
NOV 20, 2019
Chemistry & Physics
NOV 20, 2019
What are "Tears of Wine"?
Have you noticed: every time after pouring wine, near the top of a wine glass there's always a ring of liquid, where droplets form and continue to fall...
NOV 24, 2019
Space & Astronomy
NOV 24, 2019
SpaceX's Starship Prototype Explodes During Pressure Test
SpaceX is best known for its Falcon-series of rockets that often resupply the International Space Station and ferry satellites into space to deploy an orbi...
JAN 14, 2020
Space & Astronomy
JAN 14, 2020
How Much Do You Know About Jupiter?
Jupiter, recognized by most as the largest known planet in our solar system, is a particularly interesting place. So interesting, in fact, that NASA sent a...
JAN 20, 2020
Microbiology
JAN 20, 2020
Microbes Create a More Sustainable Building Material
Concrete is the second most widely consumed resource on the planet (after water), and it has a massive carbon footprint....
JAN 20, 2020
Chemistry & Physics
JAN 20, 2020
Oldest Materials on Earth - They Predate Our Solar System
In 1969, a meteorite crashed through the sky and landed near the small town of Murchison, Australia. Had shattered into many fragments after its dramatic l...
JAN 30, 2020
Chemistry & Physics
JAN 30, 2020
New Infrared Spectroscopic Method Grants Scientists Unprecedented "Seeing" Power
Infrared spectroscopy is a popular scientific method to identify and study molecules based on their absorption of infrared light. Scientists at the Max Pla...
Loading Comments...