Inclusion Criteria:  Women 18 years or older with histologically confirmed unifocal breast lesion and identified as a candidate for BCS, this includes patients with high-risk, premalignant (eg. ductal carcinoma in-situ), or malignant (eg. invasive ductal carcinoma) lesions Lesions must be non-palpable and require pre-operative localization for surgical guidance Lesions must be visible as determined by preoperative breast mammogram and / or ultrasound imaging. Pre-operative MRI is at the discretion of the treating surgeon.  Exclusion Criteria:  Biologically male patients Locally advanced malignant breast cancer Any absolute contraindications to BCS Pregnancy or lactation Existing allergy to metallic seed materials Patients requiring MRI after MOLLI seed placement