A new device called a photoacoustic mammoscope combines infrared light and ultrasound to create 3-D maps of the breast. Its creators hope that it could someday replace the x-rays used in traditional mammography for routine breast cancer screenings. Breast cancer is one of the most common forms of the disease and a leading cause of death among women worldwide. Traditional mammography, which uses x-rays, is routinely used to screen women. But a new imaging tool developed at the University of Twente might one day help detect breast cancer early, when it is most treatable. The photoacoustic breast mammoscope uses a combination of infrared light and ultrasound to create 3-D maps. In the new technique, infrared light is delivered in billionth-of-a-second pulses to tissue, where it is scattered and absorbed. The high absorption of blood increases the temperature of blood vessels slightly, causing them to undergo a slight but rapid expansion. While imperceptible to the patient, this expansion generates detectable ultrasound waves that form a 3-D map of the breast vasculature. Since cancer tumors have more blood vessels than the surrounding tissue, they are distinguishable in this image. Top: A top and side view of a 3-D reconstructed phantom object made of gels and other materials that mimic human tissue. The background of this phantom mimics normal breast tissue, while several objects embedded within the material mimic blood vessels and tumors. Bottom: Two slices of images of a reconstructed phantom taken with the new device. The locations of five objects are indicated with arrows: Objects 1 and 2 mimic blood vessels, while objects 3 to 5 mimic tumors. Images courtesy of Wenfeng Xia, Biomedical Photonic Imaging group, University of Twente. Currently, the resolution of the images is not as fine as that obtained with existing breast imaging techniques like x-ray mammography and MRI. In future versions, assistant professor Srirang Manohar, who led the research, graduate student Wenfeng Xia and colleagues expect to improve the resolution. They also plan to add the capability of using several different wavelengths of light at once, which is expected to improve detectability. The Twente researchers, who belong to the Biomedical Photonic Imaging group run by professor Wiendelt Steenbergen, have tested their prototype in the laboratory using phantoms — objects made of gels and other materials that mimic human tissue. In a small clinical trial last year, they showed that an earlier version of the technology could successfully image breast cancer in women. If the instrument is commercialized, it will likely cost less than MRI and x-ray mammography, Manohar and colleagues said. A schematic illustration of the imaging system and the ultrasound detector. "We feel that the cost could be brought down to be not much more expensive than an ultrasound machine when it goes to industry," said Xia, who is first author on a new paper about the research. But before it can be used routinely, the device first has to prove it's at least as effective as the mammography, MRI and ultrasound already widely used for breast cancer screenings and diagnosis. That will happen in larger clinical trials. "We are developing a clinical prototype that improves various aspects of the current version of the device," said Manohar. "The final prototype will be ready for first clinical testing next year." The device is described in a paper published in The Optical Society's open-access journal Biomedical Optics Express. (http://dx.doi.org/10.1364/BOE.4.002555). For more information, visit: www.utwente.nl/tnw/bmpi/