Photoacoustics Shows Promise for Identifying Breast Cancer

May 14, 2012

Researchers are in the first stages of testing a new technology that may allow radiologists to detect breast tumors with improved accuracy without exposing patients to radiation.

Researchers in The Netherlands are in the first stages of testing a new technology that may allow radiologists to detect and see breast tumors with improved accuracy without exposing patients to radiation.

Working with 12 patients with known malignancies, researchers at the University of Twente and Medisch Spectrum Twente Hospital in Oldenzaal, tested whether they could identify and see breast tumors through a technique called photoacoustics. Although the research, published in the open-access journal Optics Express, isn’t yet ready for clinical implementation, the findings are encouraging, according to some industry experts.

Photoacoustics is a hybrid optical and acoustical imaging technique that uses red and infrared light technology, known as optical mammography, to image tissue and detect tumors. This method can identify cancers because the blood hemoglobin feeding the tumors absorbs red wavelengths, exposing the contrast between tumors with increased blood vessel activity and normal areas of the breast.

"While we're very early in the development of this new technology, it is promising,” said Michelle Heijblom, a researcher and PhD student at the University of Twente in Enschede, in a statement about the study. “Our hope is that these early results will one day lead to the development of a safe, comfortable, and accurate alternative or adjunct to conventional techniques for detecting breast tumors."

However, targeting tumors with photoacoustics can be difficult. The limited bandwidth of the photoacoustic detector can sometimes convey the wrong size or shape of a tumor. To overcome the hurdle, researchers paired the technique’s ability to differentiate between benign and malignant tissues with ultrasound and created the Twente Photoacoustic Mammoscope (PAM).

The device uses a 1,064-nanometer-wavelength laser to scan the breast, and the increased light absorption causes the malignant tumor’s temperature to rise. The result is a pressure wave. An ultrasound detector on the side of the breast picks up the wave and sends it to the PAM system for image reconstruction.

According to study data, this photoacoustic technique compares favorably for clinical breast cancer diagnosis against conventional diagnostic X-ray, ultrasound imaging, MRI, and tissue exams. Results also indicate this method produces higher contrast malignant tissue images than traditional X-ray mammographies.

These positive outcomes have caught the eye of breast cancer experts in the United States. The results, they said, are an encouraging step in the fight against breast cancer.

“It sounds very promising,” said Cherie Zumiak, DO, associate professor of radiology and director of breast imaging at the University of North Carolina at Chapel Hill School of Medicine and the North Carolina Cancer Hospital. “I look forward to more research in this area.”

Further exploration is, in fact, the next step, according to investigators.

“PAM needs some technical improvements before it is a really valuable clinical tool for diagnosis or treatment of breast cancer,” Heijblom said in the statement. “Our next step is to make those improvements and then evaluable less obvious potential tumors, benign lesions, and normal breasts with it.”

These are diagnostic images of a mixed infiltrating lobular and ductal carcinoma in the right breast of a 57-year-old patient. The cranio-caudal X-ray mammogram (left) showed an architectural distortion of about 22 mm in the lateral part of the right breast. Ultrasonography (middle) showed the presence of an unsharply edged hypoechoic lesion with a hyperechoic border at the expected location. Photoacoustic mammography (right) showed a confined high-contrast abnormality with a contrast in excess of five and a maximum diameter of 14 mm at the expected lesion depth. Here, a transversal cross-section through this abnormality is visualized. Credit: Michelle Heijblom, University of Twente