New imaging technique could speed cancer detection

April 4, 2012

(Medical Xpress) -- A new imaging technique relies on light and sound to create detailed, color pictures of tumors deep inside the body. The technology, called photoacoustic tomography, may eventually help doctors diagnose cancer earlier than is now possible and to more precisely monitor the effects of cancer treatment — all without the radiation involved in X-rays and CT scans or the expense of MRIs.

Clinical trials are in the planning stages, but studies in animal models have given researchers a lot to get excited about. That’s because the technology can easily penetrate the body’s tissues to visualize tumors at depths never before possible.

“This technology is potentially a game changer, both in how we monitor cancer and in how soon we know it’s there,” says biomedical engineer Lihong V. Wang, PhD., who led the team of developers at Washington University in St. Louis.
For example, the technique could reveal the presence of cancer earlier by showing oxygen use by tissues. Excessive oxygen-burning, called hypermetabolism, is a hallmark of the disease. In the early stages, there isn’t much else to go on, so photoacoustic could alert physicians to the presence of the disease at its earliest stage, Wang says.

Wang explained the technology April 3 at the annual meeting of the American Association for Cancer Research in Chicago. Wang’s presentation follows his publication of a related paper March 23 in Science.

Wang, who is affiliated with the Alvin J. Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine, is working with Washington University physicians to evaluate the technology for four uses: identifying the sentinel lymph nodes for breast cancer staging, which may eliminate the need for surgical lymph node biopsies; monitoring early response to chemotherapy; imaging melanomas; and imaging the gastrointestinal tract.

A major challenge for diagnosing is the inability to see small tumors growing in the body. Physicians have come to accept the grayness of X-ray images and CT scans (which are based on X-rays), where structures appear as lights and shadows. But they are a poor substitute for “photographs” of our insides.

No such photographs exist because light can’t penetrate soft tissue. Tissues scatter light, which limits the ability to see anything beyond the depth of about a millimeter. But scattering doesn’t destroy the light, which can reach a depth of about 7 centimeters, or about 3 inches.

Photoacoustic imagery brings together the best of both worlds — light and sound. It converts light absorbed by soft tissues in the body into sound waves, which easily penetrate tissues. The tissue to be imaged is then irradiated by a nanosecond-pulsed laser at an optical wavelength.

Absorption of light by molecules beneath the surface creates a thermally induced pressure jump that launches sound waves, which are measured by ultrasound receivers at the body’s surface and reassembled to create what is, in effect, a photograph.

Photoacoustic images have a much higher contrast than X-ray images because there are many highly colored molecules in the body that naturally serve as contrast agents. These include hemoglobin, which changes color as it gains or loses oxygen, but also melanin, the pigment that makes moles dark, and DNA, which in its condensed form in the cell nucleus is darker than the cell cytoplasm.

With a little help from organic dyes or genes engineered to express colorful products, photoacoustic tomography can also image tissues, such as lymph nodes, that would otherwise blend in with their surroundings.

“Every issue of every top journal publishes exciting lab discoveries, but only a tiny fraction of them are ever translated into clinical practice,” he says. “My hope is that photoacoustic tomography can help translate microscopic lab discoveries into macroscopic clinical practice.”

Explore further: Photoacoustic tomography can 'see' in color and detail several inches beneath the skin

Related Stories

Photoacoustic tomography can 'see' in color and detail several inches beneath the skin

March 22, 2012
Every new imaging technology has an aura of magic about it because it suddenly reveals what had been concealed, and makes visible what had been invisible. So, too, with photoacoustic tomography, which is allowing scientists ...

Photoacoustics technique detects small number of cancer cells

March 27, 2012
Researchers have developed multiple techniques and procedures to detect cancer cells during the earliest stages of the disease or after treatment. But one of the major limitations of these technologies is their inability ...

Recommended for you

Stem cell therapy attacks cancer by targeting unique tissue stiffness

July 26, 2017
A stem cell-based method created by University of California, Irvine scientists can selectively target and kill cancerous tissue while preventing some of the toxic side effects of chemotherapy by treating the disease in a ...

Understanding cell segregation mechanisms that help prevent cancer spread

July 26, 2017
Scientists have uncovered how cells are kept in the right place as the body develops, which may shed light on what causes invasive cancer cells to migrate.

Study uncovers potential 'silver bullet' for preventing and treating colon cancer

July 26, 2017
In preclinical experiments, researchers at VCU Massey Cancer Center have uncovered a new way in which colon cancer develops, as well as a potential "silver bullet" for preventing and treating it. The findings may extend to ...

Compound shows promise in treating melanoma

July 26, 2017
While past attempts to treat melanoma failed to meet expectations, an international team of researchers are hopeful that a compound they tested on both mice and on human cells in a petri dish takes a positive step toward ...

Study may explain failure of retinoic acid trials against breast cancer

July 25, 2017
Estrogen-positive breast cancers are often treated with anti-estrogen therapies. But about half of these cancers contain a subpopulation of cells marked by the protein cytokeratin 5 (CK5), which resists treatment—and breast ...

Breaking the genetic resistance of lung cancer and melanoma

July 25, 2017
Researchers from Monash University and the Memorial Sloan Kettering Cancer Center (MSKCC, New York) have discovered why some cancers – particularly lung cancer and melanoma – are able to quickly develop deadly resistance ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.