Biomedical engineer Lihong Wang and his research team at Washington University in Missouri have developed a new, composite imaging technique — photo-acoustic tomography (PAT) — that provides greater functional information about potential cancerous tissue than present x-ray-based imaging techniques.
Light and sound are both forms of electromagnetism and can be inter-mingled, even transformed into each other.
“Instead of looking at optical structures, we are listening to optical structures.”, says Prof. Wang.
The new PAT technique utilizes laser light to generate pressure waves (or ‘acoustic’ waves) within tissue. Laser light inside densely-layered tissue tends to get absorbed and/or scattered throughout the tissue. Thus, it does not reflect back to its source and subsequently provide information.
But the laser light does rapidly increase the temperature of targeted tissue, and this increase in temperature leads to an increase in pressure (Boyle’s Law) which creates pressure waves. The pressure waves are picked up by sound transducers, which send their signals to a computer. The computer program records and measures the arrival times of the waves, then optically re-constructs a real-time, 3D image of the tissue (on the molecular level); from millions of these photo-acoustic readings (‘slicings’) the researchers are able to pinpoint the location of potential cancer cells with greater accuracy.
The researchers believe that the new technique is superior to x-ray mammography (used in breast cancer screenings), which utilizes ionizing radiation and produces many false positives. The imaging technology can also identify areas where oxygen uptake is greatest — often a sign of tumorous growth.
“[the new technique] uses more functional and varied information [so that] we can identify real cancers from the false positives,” says Wang.
The new imaging technique is still in its early testing phase.
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For more information and photos relating this innovation, check out this WUSTL news article.
Top photo: (Normal (left) versus cancerous (right) showing standard mammography image; not a PAT image) US Gov / NIH