Tracking tumours is a tricky business. Scientists have discovered recently, however, that ‘listening’ might make it easier. This image of a melanoma (represented in gold) and blood vessels (in red) growing under mouse skin, was produced by doing just that. Photoacoustic imaging exploits small differences in the chemical make-up of tissues, cells and molecules that mean they absorb light differently. When a laser beam is directed through tissue, absorbed light causes temperature and pressure changes that create sound waves. The symphony of sound waves is detected at the tissue surface and converted into photographic images. Finely tuned images are possible because, unlike light waves, sound waves don’t scatter much and cause little interference. This technique detects differences in tissue chemistry by ‘listening’ out for changes like altered blood flow, which might betray the presence of disease, Clinical trials are now underway to sound out photoacoustic imaging for detecting early-stage cancers.
Written by Caroline Cross
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