A gamma camera has been customized to detect the earliest signs of breast cancer, before it can be felt as a lump or seen in a mammogram.

The functional imaging device, presented at the 26th Annual San Antonio Breast Cancer Symposium earlier this month, has been tested with promising results in artificial breasts. Human testing is planned for the spring.

Whitaker investigator Martin Tornai, PhD, associate professor of radiology and biomedical engineering at Duke University, built a miniature gamma camera mounted to a rotating platform. The camera encircles the breast up close to get a high-resolution, 3-D image.

The device is sensitive enough to detect some of the earliest chemical changes that precede malignancy. Lab tests suggest the camera will be able to see into dense breast tissue and large breasts that X-ray mammography has more difficulty penetrating. It can examine the axillary lymph nodes for spreading cancer cells. These lymph nodes lie around and behind the pectoral muscle, another area largely inaccessible to X-ray mammography.

"If we can detect subtle changes in cells before a tumour has developed, we have a better chance of treating the abnormal cells," Tornai said.

Tornai's device relies on radioactive tracers--sestamibi, for one--that are injected into the patient's bloodstream. Tracers carry a short-lived radioactive atom visible to the gamma camera. These tracers, which are eliminated from the body after a short while and are relatively safe, accumulate in cancer cells and cells with a very high metabolic rate, characteristic of precancerous cells.

Tornai's group tested the device in artificial breasts to detect imbedded spheres that simulated tumours ranging from 4 millimeters, the size of very early malagnancies, to about 1 centimeter (less than half an inch.) These tests demonstrated that it should be possible to find some of the earliest signs of breast cancer in women.

"This technology could potentially be applied to screening women who are at high risk for breast cancer, particularly younger women who have denser breast tissue, which X-ray mammography cannot easily penetrate," Tornai said.

If successful in clinical trials, the technology could possibly supplement, not replace, mammography for cancer screening. Tornai's device gives functional information about the patient, while X-ray mammography gives structural information. Both are useful in making a diagnosis.

Tornai's research on the 3-D imaging device was supported by a Whitaker Foundation Biomedical Engineering Research Grant awarded in 2000.