Pursuing Novel, Affordable Screening for Dense Breast Tissue
Larry Fitzgerald, Ph.D.
Core
Funding Manager
The CBCRP has funded Dr. Thomas Nelson since 2005 with two grants to develop a novel, three-dimensional, whole breast ultrasound scanner. Ultrasound has been used to image the human body for at least 50 years and is one of the most widely used diagnostic tools in modern medicine. The technology is relatively inexpensive and portable when compared with magnetic resonance imaging (MRI) and computed tomography (CT).
Breast ultrasound, also known as sonography or ultrasonography, is used to evaluate breast abnormalities that are detected with mammography or a clinical breast exam. It is not FDA approved for primary screening. Ultrasound may help detect certain breast masses, and it is the best way to determine whether a benign cyst is present without using a needle to aspirate fluid. Ultrasound is also used to guide a biopsy (tissue sampling) to confirm whether a breast abnormality is cancerous.
Some advantages of ultrasound include: (1) the ability to detect lesions in dense breasts often missed by mammography, and (2) it requires no radiation or compression. However, ultrasound using typical hand-held scanners has drawbacks, such as: (1) it is operator-dependent and less standardized, (2) abnormalities in deep breast locations are difficult to detect, and (3) early breast lesions (e.g. DCIS) with micro-calcifications cannot be detected.
Dr. Nelson has a long standing in breast imaging extending back to the early days of breast MRI when his group published one of the first articles using MRI to follow changes in the breast tissues during the menstrual cycle.1 Since then he has expanded his interests in multi-dimensional imaging to 3D breast ultrasound and collaborated with Dr. Boone at University of California, Davis, in the development of a dedicated breast CT scanner.
More recently, Dr. Nelson‘s team at University of California, San Diego, is developing a dedicated volume breast ultrasound (VBUS) scanning system to improve early detection of breast cancer in patients with dense breasts by using more sophisticated analysis of breast tissue properties without the radiation dose or compression discomfort associated with mammography or the cost of MRI.
Dr. Nelson‘s team is developing their VBUS scanning system from both the medical physics imaging technology perspective and as a platform used to stabilize the breast for imaging and potentially minimally-invasive biopsy guidance. The aims are to: (1) image the entire breast in a 3-D mode, (2) increase sensitivity beyond the current 10 mm range typical for mammography, (3) allow scanning to be completed quickly, and (4) standardize the instrument to reduce operator variability.
These goals are being achieved, first, by constructing a scanning table to support the patient and expose the breast in a pendant (hanging) position to eliminate compression artifacts. The current hand held transducer is attached to a scanning gantry with motors to image the entire breast and software to process the images. This system is able to image the breast all the way to the chest wall. A total of 270 images are acquired during a complete rotation around the breast in less than 20 seconds. The software is able to process the images in a variety of ways to present the data as slices, similar to CT scanning, or as a 3-D volumetric image. The device has been tested using mock breast gel “phantoms” and tested with several volunteer women. The next phase will involve testing women with suspicious breast abnormalities (BIRADS 4 & 5).
Dr. Nelson believes that the VBUS system will offer a more affordable, readily implemented and thus widely available strategy for the earlier detection of breast cancer in patients with dense breasts. The VBUS system could be widely deployed in the community to provide a compression-free, radiation-free, low-cost, lowrisk approach to screening in an important and often poorly served population.
This work has been performed in collaboration with other CBCRPfunded investigators, including Dr. John Boone’s group at the University of California, Davis and Anne Wallace, M.D. & Christopher Comstock, M.D. also at University of California, San Diego.
Dr. Nelson received his B.A. degree in Mathematics from San Diego State University in 1972, his M.S. in Radiological Physics from San Diego State University in 1974 and his Ph.D. degree from in Medical Physics from the University of California, Los Angeles in 1977. Dr. Nelson is a fellow of the American Association of Physicists in Medicine and the American Institute of Ultrasound in Medicine.
1Nelson TR, Pretorius DH, and Schiffer LM, Menstrual variation of normal breast NMR relaxation parameters, Journal of Computer Assisted Tomography, 9(5):875-879, 1985.
