Inclusion Criteria:

          -  Men and women between 18 and 80 years of age

          -  Able and willing to give informed consent

          -  Metastatic Her2-positive breast cancer with brain metastases

          -  Karnofsky performance score 70-100

          -  ASA score 1-3

          -  Able to communicate sensations during the ExAblate BBBD procedure

          -  Able to attend all study visits (i.e., life expectancy of at least 3 months)

          -  At least 14 days passed since last brain surgery

          -  At least 6 weeks passed since last radiation treatment

        Exclusion Criteria:

          -  Brain metastases not visible on the pre-therapy imaging

          -  The sonication pathway to the tumour involves:

             i. Extensive scalp scars ii. Clips or other metallic implanted objects in the skull or
             the brain, except shunts

          -  The subject presents with symptoms and signs of increased intracranial pressure (e.g.,
             headache, nausea, vomiting, lethargy, and papilledema)

          -  Cardiac disease or unstable hemodynamics including:

             i. Documented myocardial infarction within six months of enrolment ii. Unstable angina
             on medication iii. Congestive heart failure iv. Left ventricular ejection fraction <
             50% v. Right-to-left, bidirectional, or transient right-to-left cardiac shunts vi.
             History of a hemodynamically unstable cardiac arrythmia vii. Cardiac pacemaker viii.
             Contraindications to perflutren including subjects with a family or personal history
             of QT prolongation or taking concomitant medications known to cause QTc prolongation

          -  Severe hypertension (diastolic BP > 100 on medication)

          -  Anti-coagulant therapy or medications known to increase risk of hemorrhage within
             washout period prior to treatment (i.e. antiplatelet or vitamin K inhibitor
             anticoagulants within 7 days, non-vitamin K inhibitor anticoagulants within 72 hours,
             or heparin-derived compounds within 48 hours of treatment)

          -  History of a bleeding disorder, coagulopathy or with a history of spontaneous tumour
             hemorrhage

          -  Abnormal level of platelets (< 100000) or INR > 1.3

          -  Documented cerebral infarction within the past 12 months

          -  Transient Ischemic Attack (TIA) in the last 1 month

          -  Known allergy sensitivity or contraindications to gadolinium-diethylenetriamine
             penta-acetic acid (DTPA), CT contrast, or perflutren or trastuzumab

          -  Allergy to eggs or egg products

          -  Contraindications to MRI such as non-MRI-compatible implanted devices

          -  Large subjects not fitting comfortably into the MRI scanner (generally >250 lbs)

          -  Difficulty lying supine and still for up to 4 hours in the MRI unit or claustrophobia

          -  Untreated, uncontrolled sleep apnea

          -  Positive pregnancy test (for pre-menopausal women)

          -  Known life-threatening systemic disease

          -  Severely impaired renal function

          -  Respiratory: chronic pulmonary disorders, e.g. severe emphysema, chronic obstructive
             pulmonary disease (COPD), pulmonary vasculitis, or other causes of reduced pulmonary
             vascular cross-sectional area, subjects with a history of drug allergies

          -  Any illness or medical condition that in the investigator's opinion precludes
             participation in this study