Ultrasonic Screening May Provide More Effective Breast Cancer Detection

The team, from the National Physical Laboratory (NPL; Teddington, Middlesex, UK), the UK’s National Measurement Institute, working with the University Hospitals Bristol NHS [National Health Service] Foundation Trust, are now looking to develop the technique into a clinical device.

Annually, 46,000 women are diagnosed with breast cancer in the United Kingdom, cutting-edge breast screening methods, based on X-ray mammography. Only approximately 30% of suspicious lesions turn out to be malignant. Each lesion must be confirmed by invasive biopsies, estimated to cost the NHS GBP 35 million per year. Ionizing radiation also has the potential to cause cancer, which limits the use of X-rays to single screenings of at risk groups, such as women over 50 through the National Breast Screening Program.

There is a compelling need to develop improved, ideally nonionizing, methods of detecting breast lesions and solid masses. Improved diagnosis would reduce unnecessary biopsies and consequent patient trauma from being wrongly diagnosed.

Ultrasound fulfills many of the requirements it is safe, low cost, and already extensively used in applications such as fetal scanning. However, the quality of the images is not yet good enough for reliable diagnoses. Part of the difficulty lies with the current detectors used. Different biologic tissues have different sound speeds, and this affects the time taken for sound waves to arrive at the detector. This can distort the arriving waves, in extreme cases causing cancellation them to cancel each other out. This results in imaging errors, such as suggesting abnormal inclusions where there may be none.

The new method works by detecting the intensity of ultrasonic waves. Intensity is converted to heat that is then sensed by a thin membrane of pyroelectric film, which generates a voltage output dependent on the temperature rise. Imaging detectors based on this new principle should be much less susceptible to the effects caused by the uneven sound speed in tissues.

This technique, when used in a computed tomography (CT) configuration, should produce more accurate images of tissue properties and so provide better identification of breast tissue abnormalities. The goal of CT imaging is to generate a cross-section map of the tissue, which defines how the acoustic characteristics vary across the tissue. Using this map, it is possible to identify abnormal inclusions.

An initial feasibility project has proved the theory by testing single detectors using purpose-built artifacts. These artifacts were designed to include well-defined structures, enabling the new imaging technique to be compared with more conventional techniques. The findings validated that the new detectors generated more effective maps of the internal structure of the artifacts than existing techniques.

Having received positive findings and validated the potential of the project, NPL is now seeking funding to develop the work further. They hope to produce a demonstrator using a full array of 20 sensors, which should allow more rapid scanning and move the concept towards a system, which might eventually be used clinically. It is hoped that this will provide both a suitable resolution and fast enough scanning to become a viable replacement for current clinical scanners. Following successful completion of the demonstrator, NPL and partners will look to work with a manufacturer to commercialize the technology.

Dr. Bajram Zeqiri, who leads the project at the National Physical Laboratory, said, “Our initial results are very promising. […] we’re very excited about its potential and with the right funding, support, and industry partners, we may well have something here which could have a huge and positive impact on cancer diagnosis and the lives of many thousands of women.”

Related Links:
UK National Physical Laboratory