Detecting cancer through laser-induced ultrasound

Researchers at the University of Missouri use photoacoustic technique to locate melanoma cells, thus helping doctors more accurately identify melanoma stages.

Viator uses a tabletop device to scan a lymph node biopsy with laser pulses. Pinar Istek

To determine if there is cancer in one's lymph nodes, a typically advanced stage requiring more aggressive treatment, pathologists are stuck performing several specific, detailed tests that may or may not target the cancerous cells. Using the needle-in-a-haystack analogy would be apt.

But thanks to the work of researchers at the University of Missouri in Columbia, a technique using photoacoustics could scan a lymph node biopsy with laser pulses, whereby the pigment of melanin reacts to the laser's beam, absorbing the light, and heating and cooling (read: expanding and contracting) rapidly. This produces a popping sound that's detectable by special sensors.

Using this new method, pathologists could soon be able to examine an entire biopsy and identify the general area of the node that has cancer, giving pathologists a better (and faster) idea of where to look for the cancer.

"It's very similar to identifying a prize inside a cake," says John Viator, assistant professor in the departments of biological engineering and dermatology, in a news report this week:

"Instead of looking through the entire cake, we can use our ultrasound to pinpoint a slice or two that might contain the 'prize,' he said. "In the case of the lymph nodes, when you get a signal, this alerts the pathologist that this is an area of the node that might contain cancer cells. At that point, a pathologist would be able to narrow down the search, saving time and money."

Photoacoustic Detection of Melanoma in Lymph Nodes from MU News Bureau on Vimeo.

Since a paper outlining Viator's research, titled "Photoacoustic Detection of Melanoma Micrometastatis in Sentinel Lymph Nodes," was published in the Journal of Biomedical Engineering in July 2009, he has partnered up with University of Missouri Professor Jae Kwon, whose home cancer detection kits we covered last week . The team is investigating how gold nanoparticles might be able to "tag" non-melanoma particles to extend this work to other types of cancer, such as breast cancer.

"Melanoma has its own native pigment, melanin, but the breast cancer cell, say, doesn't have its own color, so is invisible to laser light," Viator said. "But we're working with a group on campus that is functionalizing nanoparticles, basically painting these cells with color so we can do this same type of photoacoustic identification in other cancers."

Viator says he hopes to commercialize this new technology, which he calls "an important tool in our fight against cancer," in the near future. His most recent work on photoacoustics is due to appear in the Journal of Biomedical Engineering in the coming months.

 

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