New Imaging Technique Could Spot Early Cancers

Lasers heat nanotubes, then docs listen for ultrasound waves released showing tumors

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MONDAY, Aug. 18, 2008 (HealthDay News) -- Nanotechnology may offer doctors a noninvasive way to detect early stages of cancer and also help monitor treatment, a new report says.

Researchers at Stanford University School of Medicine recently demonstrated the new approach using "smart" targeted carbon nanotubes to zero in on cancer cells in living mice, followed by laser scans of the animals in which the nanotubes absorbed the laser energy and released ultrasound waves to highlight the locations of the tumor cells.

"This imaging modality allows us to see things we've never been able to see before," study author Adam de la Zerda, a doctoral student in Stanford electrical engineering, said in a news release issued by the university.

The findings were expected to be published online Aug. 17 in Nature Nanotechnology.

The technology takes advantage of the "photoacoustic effect," a physical phenomenon in which light hits an object and is converted into sound. Shining light on an object heats it up, de la Zerda said.

"Think of a black car parked in the sun," he said. The car warms up, and the metal expands. Later, the cooling, shrinking metal makes little "tink" sounds.

"We shine light on a nanotube and listen to the ultrasound waves coming out of it," de la Zerda said.

The technique is faster and costs less than an MRI scan and requires no ionizing radiation like a PET-CT scan, the researchers said. Its ability to look 2 inches deep into the body would make it helpful for looking at tissues in the breast or prostate gland.

The method is sensitive enough to detect minute, early tumors that normally can't be seen, the researchers said. Also, the scanners could also be adapted to endoscopes, enabling views of internal organs.

Coatings on the nanotubes could also be altered so doctors could receive diagnostic information about a tumor, de la Zerda said. For instance, molecules put on nanotubes could tell a doctor which anti-cancer drugs would work on a breast tumor.

"We will be able to ask a tumor: Are you responding to chemotherapy or not?" de la Zerda said. "This should give us early information long before the tumor shrinks or grows."

A companion study in mice, published in Nature Nanotechnology in April, found the carbon nanotubes appear to be safe to inject, although further testing is needed before testing can begin in humans.

More information

The National Cancer Institute has more about nanotechnology uses in cancer treatment.

SOURCE: Stanford University School of Medicine, news release, Aug. 17, 2008


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