This phase I trial studies the performance, including ultrasound visibility, of an optimized ultrasound twinkling marker in imaging lymph nodes in patients with clinically node-positive breast cancer. In patients with biopsy-proven breast cancer, biopsy markers are used to identify the sites of cancer involvement in both the breasts and lymph nodes. These biopsy markers are critical for guiding surgical management many months after the marker is placed. For breast radiologists and breast surgeons, there is a need for simple, consistent visibility of biopsy markers by ultrasound, particularly several months after marker placement. Ultrasound is the imaging method of choice, particularly for lymph nodes in the armpit (axilla). Ultrasound is non-ionizing and is more comfortable for patients compared to mammography. However, ultrasound visibility of these markers is challenging and inconsistent, with ultrasound failing to detect the marker approximately 25% of the time. The Mayo-designed investigational biopsy marker takes advantage of an ultrasound phenomenon called twinkling artifact. The Mayo-designed optimized ultrasound twinkling marker may work better than standard biopsy clip marker in imaging lymph nodes in patients with clinically node-positive breast cancer.

Inclusion Criteria:

• Patient 18 years or older with breast cancer and biopsy-proven malignant involvement of an axillary lymph node
• Surgical management will be determined by the surgeon, who will decide if preoperative Iodine (I)-125 seed localization of the positive node is necessary or if they will retrieve the positive node with intraoperative ultrasound guidance. During surgery, the targeted node, its associated biopsy markers, I-125 seed if placed, and optimized twinkling marker will be resected. The position of the marker in the lymph node or proximity to the node will be noted from the surgical and pathology documentation
• Surgery will be performed by one of the surgeons in the Division of Breast and Melanoma Surgical Oncology (Doctor [Dr.] Judy Boughey, Dr. Amy Degnim, Dr. Tina Hieken, Dr. Jeffrey Johnson, Dr. Mary Mrdutt, Dr. Shon Black)
• Patients must be able to understand the study procedures and comply with them for the entire length of the study
• No contraception is necessary or required

Exclusion Criteria:

• Patients who are pregnant
• Current drug or alcohol use or dependence that, in the opinion of the site investigator, would interfere with adherence to study requirements
• Current or past participation within a specified timeframe in another clinical trial, as warranted by the administration of this intervention