Statement: Patients with invasive breast cancer with a diameter of less than 4 cm are included in the primary trial.
Primary_evidence: Inclusion Criteria:   18 years or older.   Ipsilateral biopsy-proven invasive breast cancer <5 cm in maximal dimension by Ultrasound or Mammography.   No abnormal axillary nodes identified on grayscale AUS, or abnormal nodes with benign subsequent FNA biopsy. Exclusion Criteria:   Pregnant or nursing women   Prior SLN dissection   Neoadjuvant chemotherapy.   Prior axillary lymph node surgery.   Prior history of ipsilateral breast cancer. Known or suspected: Cardiac shunts Known or suspected: hypersensitivity to perflutren, blood, blood products or albumin Known or suspected: hypersensitivity to a prior OPTISON administration