Published on the March 22, 2012, DiagnosticImaging.com Website
By Whitney L.J. Howell
If you had the opportunity to test a technology that gave you clear, full-color images from deeper within the body, would you do it? You could soon find yourself faced with this question as photoacoustic tomography works its way through the clinical trial process.
Investigators have researched this technology that pairs light and sound for roughly 20 years. Now, biomedical engineers from Washington University at St. Louis have taken steps to make the health-hazard-free imaging method available to providers and patients. And clinical trials are already under way to visualize sentinel lymph nodes for breast cancer staging – just one of several potential applications of this technology.
“My hope is that photoacoustic tomography will impact both basic science research and clinical utility,” said Lihong Wang, PhD, Washington University’s Gene K. Beare Distinguished Professor of Biomedical Engineering, who details this new imaging technology in the March 23 issue of Science. “Photoacoustic enables bio-research on many scales. Clinically, we hope it accelerates the translation of microscopic lab discoveries to the macro clinical practice. Very few discoveries ever translate
to the clinic, and we believe photoacoustic will make bridging that gap much smoother.”
How It Works
Instead of relying solely on the easily-scattered light photons used in X-rays to provide images, photoacoustic tomography converts light absorbed in soft tissue into sound waves and irradiates the targeted tissue with a nanosecond-pulsed laser set to an optical wavelength. These sound waves break apart 1,000 times less than light, allowing you to gather images at a depth of 7 centimeters — 70 times deeper than X-ray.
According to Lihong Wang, some of the molecules absorbed in tissues produce heat that pushes sound waves to the skin’s surface. Ultrasound receivers collect that data and create images, similar to photographs, that have higher contrasts than X-rays. Naturally-colored molecules, such as hemoglobin and melanin, work as they body’s own contrast agents and cooperate with organic dyes or other genetically-engineered genes to help produce the images.
“A lot of the information we have comes from the visual world,” he said. “By using photoacoustic in the body, we can mimic what we see with the naked eye. Firing these photons into tissue produces very good images.”
To read the remainder of the article: http://www.diagnosticimaging.com/ct/content/article/113619/2049780