Photoacoustic device in development could diagnose breast cancer accurately

A team of researchers at the University of Twente (Enschede, Netherlands) and collaborators is developing a device that intends to remove the discomfort and uncertainty involved in breast cancer diagnosis. The device employs both light and sound together in a technique called photoacoustics, which combines lasers and photonics with ultrasound detection.

The size of a hospital bed, a patient lies face down placing their breast snugly into the hemispherical bowl-shaped reader that is lined with up to a hundred optical fibers and several ultrasound detectors. Multiple images of a suspect breast and tumor are then acquired from dozens of different angles before assembling the multiple shots into a single 3D image.

The Photoacoustic Ultrasound Mammoscopy for Evaluating Screening-detected Abnormalities in the Breast (PAMMOTH) project hopes to lead the research into photoacoustic, real-time 3D imaging of suspicious lesions. "We are creating an imaging device that we hope will reduce all of the stages involved in spotting breast cancer into one convenient appointment in order to reduce time, uncertainty, and the number of unnecessary biopsies," explains PAMMOTH project coordinator Srirang Manohar.

The device works by sending short pulses of light into the breast towards the suspected lesion. Some of the delivered energy will be absorbed in the tissue and converted into heat, leading to transient thermoelastic expansion, or a mechanical 'push' signal from the suspected tumor.

Ultrasound detectors on the surface of the breast, from the hemispherical reader where the breast is placed, can then detect and measure these 'push' signals before analyzing them on site. Here, the imager can look into the hemoglobin (the oxygen-carrying protein in the blood) activity within the suspected tumor.

Since tumors consume oxygen at high rates to survive, lower oxygenation levels around a suspect lesion could tell a physician that a suspect lump is more likely to be a malignant growth than not. The imager employs a multiwavelength illumination in the near-infrared wavelength region to extract information about blood oxygenation, using PAMMOTH's own image reconstruction methods.

As part of the PAMMOTH team, researchers at University College London (UCL) are working on the mathematics, the image reconstruction, and the analysis of the signals to determine how aggressive a tumor could be.

By gathering key information about the hemoglobin and oxygenation levels to and from the suspected tumor, the user could diagnose how likely it would be for the tumor to spread or whether it was simply benign. "An aggressive tumor has a high metabolism and consumes oxygen more rapidly than normal tissue or a benign lesion," Manohar says. "Our instrument and the mathematical approaches we are developing could allow us to check the oxygen saturation rate accurately. If a patient's oxygen saturation rate was found to be considerably lower than surrounding tissue, then we could pinpoint where an aggressive tumor could be and radiologists could understand how the tumor is likely to behave."

Current techniques to diagnose breast cancer such as x-ray mammography, ultrasound, or magnetic resonance imaging (MRI) scans can sometimes fail to spot a tumor from healthy tissue or a benign abnormality, resulting in tumors that are missed and unnecessary biopsies being carried out.

"A prime focus of the PAMMOTH project is to develop an imager and data analysis to be able to intervene at a very early stage," Manohar says. "We need to be able to say whether a suspect lesion is good or bad. This technique would have a substantial impact upon the money spent on unnecessary biopsies, as well as to remove the trauma involved in a diagnosis for women around the world."

The PAMMOTH team hopes to have a prototype ready for completion in 2021.

For more information, please contact Srirang Manohar at [email protected].