To evaluate the safety and efficacy of using NaviFUS™ system in patients with drug resistant epilepsy

This is a pilot, single blind, randomized crossover design, and single center. DRE patients with a determined epileptogenic foci will be enrolled. After completing the informed consent, patients will enter the 28-day screening period for baseline observation. Patients who had at least 3 seizures during the screening period will be eligible to participate the clinical trial. Eligible patients will be randomized into two groups to receive Sham treatment or FUS treatment on day 1. After FUS/Sham treatment, patients will be under home monitor to record the seizure by daily diary card for 1 month. After 1 month (Day 30±7), patients will be crossed over to the other treatment. Another one month observation will be necessary. In this trial, patients will totally receive 2 treatments: one FUS treatment, and one Sham treatment. Sixty (±7) days after day 1, patients will have a follow-up visit and overall evaluation.

Inclusion Criteria:

1. Male or female patients aged ≥20 years old.
2. Patients with drug-resistant epilepsy (defined as at least 3 ASM failed) and 1-4 ASM at the time of study entry.
3. An epileptogenic foci is determined by comprehensive presurgical evaluation
4. Seizure number is countable and had been recorded at least 6 times within 2-month in medical history before screening period.
5. Seizure number had been recorded at least 3 times within 28-day screening period.
6. Willing and able to sign written informed consent and be able to comply with the study protocol during the study period.

Exclusion Criteria:

1. Patients with concurrent active psychiatric or mood disorders that in the opinion of the investigator would interfere with participation in the study.

2. Presence of pacemaker, implantable cardioverter-defibrillator (ICD), permanent medication pumps, cochlear implants, or deep brain stimulation (DBS)

3. The skull bone area traversed by the sonication pathway is covered by scars, scalp disorders (e.g., eczema), or atrophy of the scalp.

4. Clips or other metallic implanted objects in the FUS exposure path, except shunts.

5. Abnormal coagulation profile:

   1. Platelet (PLT) < 100,000/μL.
   2. prothrombin time (PT) >14 sec.
   3. activated partial thromboplastin time (APTT) >36 sec.
   4. and international normalized ratio (INR) > 1.3.

6. Pregnant or breast-feeding women.

7. Coexisting medical problems of sufficient severity to limit compliance with the study.

8. Known sensitivity/allergy to Magnetic Resonance Imaging (MRI) contrast agents or any of its components.

9. Use of any recreational drugs or history of drug addiction or known history of substance or alcohol abuse.

10. Patients have received an investigational drug or an investigational device within 4 weeks prior to the study.

11. Any other condition that, in the investigator's judgment, might affect study endpoints or might increase the risk to the patients or decrease the chance of obtaining satisfactory data needed to achieve the objectives of the study.

12. Any ASM treatment change during the baseline (screening period)

13. Vagus nerve stimulation (VNS) dosing changes within 2 months before baseline (screening period).

14. Radiofrequency thermocoagulation (RFTC) within 2 months before baseline (screening period).

15. Any other condition that, in the investigator's judgment, patient not applicable to participate this study.