The use of 3D ultrasound is feasible for mapping and studying breast ductal systems, according to a study published this month in the Journal of Ultrasound in Medicine.

According to Mark J. Gooding, PhD, from the department of obstetrics and gynecology at the University of Oxford in Oxford, England, and colleagues, while most research into breast ultrasound analysis has been concerned with the detection and diagnosis of lesions, the fact that most malignancies original in the epithelial tissues of the ducts makes the ductal system an important area of study.

“The ability to generate a 3-dimensional (3D) map of the ductal structure of the breast could have applications in the detection of cancer by highlighting abnormal ductal structures and in the planning and monitoring of its treatment by defining interconnected functional regions or lobes,” wrote the authors, adding that the use of quantitative 3D ultrasound could enable further research into lactation and breast-feeding.

The researchers acquired 3D ultrasound data of the breast using a mechanical system, which captures data in a conical shape covering most of the breast without excessive compression. Manual mapping of the ductal system was performed using custom software for data from four volunteers. The volunteers were lactating mothers who had successfully established a breast-feeding routine with a single infant. Both breasts of each volunteer were scanned before a breast-feeding session.

The researchers used customized software to manually trace the ductal structures. The software enables researchers to view the data set in the radial and coronal planes. A 3D model of the ductal systems was exported to 3D Slicer, a medical visualization program created that the Massachusetts Institute of Technology Artificial Intelligence Laboratory in Cambridge, Mass., in collaboration with the Surgical Planning Laboratory at the Brigham and Women’s Hospital in Boston, from which the “arborescent” structure of the ductal system could be displayed in 3D.

According to the authors, mapping the structures in 3D allowed viewers to better differentiate between ducts and blood vessels, which both appeared as dark linear structures in 2D.

The authors found that for each of the four subjects of the study, only a small number of ductal structures were engorged with milk, “suggesting that the lactiferous activity of the breast may be localized.” The enlarged ducts were found in the inferior lateral quadrant of each breast and the researchers also observed that the enlarged, milk-storing parts of the duct were spread throughout the ductal system.

They concluded that 3D mapping of the ductal system of the breast could have a number of clinical applications, including aiding visualization of 3D ultrasound data, detecting and diagnosing breast lesions, defining surgical excision margins based on the extent of the connected lobe rather than the lesion size, guiding ductal endoscopy, and aligning 3D breast scans taken of the same breast at different times.” Further applications may be found in the study of the anatomy and mechanisms of lactation and breast-feeding,” the authors wrote.

The authors also concluded that while it was possible to use ultrasound to visualize 3D structure of the milk-laden ducts in an uncompressed breast and to manually trace milk-laden ducts less than 1 mm in diameter, it was not possible to delineate all ducts in the rest of the breast. This means, the authors wrote, that if ductal mapping from 3D ultrasound is to be used for purposes such as detecting and diagnosing breast lesions or guiding lobe size for surgical excisions, improved ultrasound resolution will be a necessity.