Inclusion Criteria:
1. 25-64 years, inclusive.
2. Patients who are able and willing to give consent and able to attend study visits, as determined by both study psychiatrist and the surgeon.
3. DSM-5 diagnosis of Obsessive-Compulsive Disorder (OCD), at least 5-year illness history, with a minimum score of 28 on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) for stage I and a minimum score of 24 on Y-BOCS for stage II.
4. Medication-refractoriness as determined by an adequate dose and duration of standard psychiatric treatments (including psychotherapy and/or pharmacology) as determined by psychiatrists associated with the study. Including specifically:
1. Failed adequate trial of three or more medications accepted as first line in the treatment of OCD such as selective serotonin reuptake inhibitors (SSRIs, e.g. fluoxetine, citalopram), selective serotonin-norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs, e.g. clomipramine) or other antidepressants at the maximal tolerated dose. Adequate maximal doses and minimal duration of these medication are listed in Table 2 below.
2. Attempted augmentation, if tolerated, by at least two medications known to be second line treatments for OCD such as clonazepam, haloperidol, risperidone, olanzapine, gabapentin.
3. An adequate trial of cognitive behavioral therapy (CBT) delivered by a therapist experienced in treating OCD. Criteria for an adequate CBT are listed in Table 3 below.
4. In stage II patients that cannot tolerate pharmacotherapy or participate in psychotherapy will be included in the study.
5. A consistent dose of all medications in the 30 days prior to study entry
6. Able to communicate sensations during the ExAblate MRgFUS treatment
Exclusion Criteria:
1. Presence of significant cognitive impairment (as measured by a score \<25 on the mini-mental state examination, MMSE)
2. Lifetime diagnosis of psychosis or bipolar disorder or presence of suicidality (as measured by a score \>=2, item 9 of the BDI or high suicidal risk measured by the Columbia Suicide Severity Rating Scale (C-SSRS)). Subjects with stable, chronic anxiety or depressive disorders may be included provided their medications have been stable for at least 3 months prior to study entry and if deemed appropriately managed by the site psychiatrist.
3. DSM-5 diagnosis of substance use disorder (SUD) within the past 6 months
4. Patients with unstable cardiac status \[e.g. unstable angina pectoris on medication; patients' medication (other than diuretic); patients on anti-arrhythmic drugs; severe hypertension (diastolic BP \> 100 on medication)\]
5. Cerebrovascular disease (e.g. CVA within 6 months), history of intracranial hemorrhage or intracranial aneurysms requiring treatment or arterial venous malformations (AVMs) requiring treatment
6. Untreated, uncontrolled sleep apnea
7. Patients with brain tumors, epilepsy, neurodegenerative disease or any other major neurological disorder
8. Patients with standard contraindications for MR imaging such as non-MRI compatible implanted metallic devices including cardiac pacemakers, size limitations, etc.
9. Known intolerance or allergies to MRI contrast agent (e.g. Gadolinium or Magnevist) including advanced kidney disease
10. Subjects who weigh more than the upper weight limit of the MR scanner table and who cannot fit into the MR scanner
11. An Overall Skull Density Ratio of less than 0.40 as calculated from the screening CT
12. Severely impaired renal function (estimated glomerular filtration rate \< 30ml/min/1.73 m2) or receiving dialysis
13. Laboratory biochemical evidence of abnormal bleeding and/or coagulopathy, including risk factors for intraoperative or postoperative bleeding (platelet count less than 100,000 per cubic millimeter or abnormal INR)
14. Current medical condition resulting in abnormal bleeding and/or coagulopathy.
15. Receiving anticoagulant (e.g. warfarin) or antiplatelet (e.g. aspirin) therapy within one week of focused ultrasound procedure or drugs known to increase risk of hemorrhage (e.g. Avastin) within one month of focused ultrasound procedure. Receiving medications or supplements that increase the risk of bleeding such as NSAIDS, Ginko Baloba and Ginseng within one week of focused ultrasound procedure.
16. Individuals who are not able or willing to tolerate the required prolonged stationary supine position during treatment
17. Are participating or have participated in another clinical trial in the last 30 days
18. Patients unable to communicate with the investigator and staff
19. Currently pregnant (as determined by history and serum HCG) or lactating
20. Life-threatening systemic disease that include and not limited to the following will be excluded from the study participation: HIV, liver failure, blood dyscrasias, etc.
