Project Summary/Abstract Rush River Research Corporation, in collaboration with the Mayo Clinic, proposes to develop a novel, user- friendly, non-invasive diagnostic tool to measure viscoelasticity of breast tissue which can be used to characterize breast lesions as benign or malignant. Breast cancer is the second most common malignancy among women in the United States and a leading cause of cancer-related deaths in females. The diagnostic journey typically involves multiple screenings and follow-on diagnostics techniques. Following positive results from these less invasive diagnostics, a biopsy is typically performed. However, most biopsies performed on women who screened positive for breast cancer using typical screening methods are found to be benign. This results in a large physical, emotional, and economic burden experienced by women who do not have cancer. Additionally, the cost of potentially unwarranted benign biopsies is more than $2 billion annually in the United States. The proposed new tool to measure viscoelasticity of tissue will provide quantitative feedback on who should receive a biopsy as well as a 2D colormap image of the tumor. The novel tool uses existing ultrasound machines and ultrasound heads and can be done at the same appointment as a diagnostic ultrasound using the same machine. A mechanical attachment is required to provide an automated, force-controlled, dynamic, axial compression and will be developed and tested using phantoms in this project. This technology will provide physicians with a better tool for decision-making and help women avoid unnecessary biopsies.