The purpose of this study is to evaluate the safety and efficacy of the ExAblate® Model 4000 Type 2.0 system as a tool to open the blood-brain barrier (BBB) in patients with probable Alzheimer's Disease (AD).

This study is a prospective, open label, single-arm, non-randomized, phase IIa trial to evaluate the feasibility, safety and efficacy of repeated, BBB opening using the ExAblate® Model Type 2.0 (220 kHz) system. Patients with diagnosis of Probable Alzheimer's Disease may qualify for a clinical trial to have three serial ExAblate BBB disruption procedures in specific areas in the brain.This study will be conducted at a single center in Canada and will enroll up to 30 patients.

Inclusion Criteria:

1. Male or Female between 50-85 years of age
2. Probable Alzheimer's Disease (AD)
3. If taking concurrent Alzheimer's medication, has been on the medication for at least 2 months with a stable dose for at least 3 months
4. Able to communicate sensations during the ExAblate MRgFUS procedure
5. Ambulatory

Exclusion Criteria:

1. MRI Findings
2. Presence of unknown or MR unsafe devices anywhere in the body
3. Significant cardiac disease or unstable hemodynamic status
4. Relative contraindications to ultrasound contrast agent or PET amyloid tracer
5. History of a bleeding disorder
6. History of liver disease
7. Known cerebral or systemic vasculopathy
8. Significant depression and at potential risk of suicide
9. Any contraindications to MRI scanning
10. Any contraindication to lumbar puncture for collection of cerebral spinal fluid
11. Untreated, uncontrolled sleep apnea
12. History of seizure disorder or epilepsy
13. Severely Impaired renal function
14. Currently in a clinical trial involving an investigational product or non-approved use of a drug or device or in any other type of medical research
15. Chronic pulmonary disorders
16. Positive human immunodeficiency virus (HIV)
17. Known apolipoprotein E allele (ApoE4) homozygosity