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12-08-2010 | Oncology | Article

New 3D photoacoustic imaging technique may improve accuracy of melanoma excision

Abstract

Free abstract

MedWire News: US researchers have developed a new three dimensional (3D) imaging technique known as photoacoustic tomography that they hope will help improve the accuracy of melanoma excision surgery.

The technique works on the principle that absorption of light heats a material slightly resulting in a small thermoelastic expansion. Using light pulsed at a specific frequency, this effect can be used to generate a sound wave.

"We detect the sound signal outside the tissue, and from there on it's a mathematical problem," said study author Lihong Wang (Washington University in St. Louis, Missouri) who developed the photoacoustic system. "We use a computer to reconstruct an image."

"We're essentially listening to a structure instead of looking at it," he said.

The 5-year survival rate is currently around 98% for people treated for early-stage melanoma, but this drops dramatically if the cancer is detected late or if there is recurrence. This makes the accuracy of initial surgery to excise melanoma very important, but currently available imaging techniques lack the accuracy for guiding surgery.

When used with a contrast agent consisting of hollow gold nanoparticles, photoacoustic tomography is particularly useful for detection of melanoma due to its high accuracy.

Writing in the journal ACS Nano, Wang and colleagues describe the improved accuracy they obtained with this technique in mice by attaching an α-melanocyte-stimulating hormone to the gold nanoparticles, which allows increased binding to hormone receptors on the melanoma cells.

They found that compared with nanoparticles tagged with an inert chemical, mouse melanoma cells took up four times as many hormone tagged nanoparticles, increasing the resulting photoacoustic signal by 36%.

Wang and co-authors believe the combination of high-resolution photoacoustic tomography and the hormone-enhanced gold nanoparticle contrast agent holds great promise for improving melanoma treatment and survival and hope to develop the technique further.

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Helen Albert

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