This proof of concept study will evaluate the ability of a new, ultrasound based technology called Bullseye Constructive Shearwave Interference (CSI) (trade name, Bullseye Elasticity Quantification) to measure lymphedema of the upper arm among breast cancer survivors.

The study's hypothesis is that the CSI device can detect the presence of clinically significant lymphedema when compared with the standard arm tape measurement.

Inclusion Criteria:

• Any subject with a history of unilateral breast cancer who has completed definitive treatment for breast cancer (i.e. previously undergone surgical resection, with or without adjuvant radiotherapy and/or chemotherapy). Subjects must have completed all recommended adjuvant radiotherapy. Subjects who continue on systemic therapy may be included at the discretion of the treating physician.
• Subjects with a history of unilateral axillary sentinel biopsy, lymphadenectomy or dissection are eligible for inclusion.
• Subjects taking hormonal therapy are eligible for inclusion
• Subject has any stage lymphedema

Exclusion Criteria:

• Active rash or skin tears/injury in bilateral upper extremities
• Subjects with history of contralateral breast cancer treatment