3D Ultrasound Elastographic Imaging and Characterization of Breast Cancer In Vivo

Breast cancer has a high mortality rate and caused about 13.7% of all cancer types deaths in women. Mammography imaging, having a good sensitivity to cancer, is used along with biopsy in a routinely manner, to differentiate between malignant and benign masses. Biopsy is an invasive procedure, and to reduce the necessity for performing it, ultrasound elastography was proposed. Elastography is a potential imaging technique to characterize breast masses, and to differentiate malignant from benign lesions, based on imaging estimated tissue strains under compression. This can result in lowering the number of unnecessary biopsies. Using 3D elastography, lesion relative stiffness with the surrounding soft tissue is estimated at different compression levels, and used as a classification parameter to judge the malignancy of the lesion. In addition, elastography provided a means of emphasizing the strain difference of the lesion from the surrounding soft tissue, which can be used as an additional classification parameter. A pilot study on volunteered patients was performed, and results were compared with biopsy diagnosis as a reference. Initial elastography results showed good agreement with biopsy outcomes. Moreover, we constructed different strain elastograms including first principal, maximum shear and von Mises strains. Those new types of elastographic volumes incorporated the normal axial and shear strains together, which provided better distinction of the hard lesion from the soft tissue. In summary, the proposed elastographic techniques can be used as a noninvasive quantitative characterization tool for breast cancer, with the capability of visualizing and separating the masses in three dimensional space.