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A Review of the Current Therapies, Challenges, and Future Directions of Transcranial Focused Ultrasound TechnologyAdvances in Diagnosis and Treatment

 

Key Points

Question  What are the neurological applications of focused ultrasound technology?

Findings  This review found that focused ultrasound technology can be applied for tissue ablation, neuromodulation, and opening of the blood-brain barrier. The US Food and Drug Administration has approved it for treating refractory essential tremor.

Meaning  Focused ultrasound is an emerging technology that has ablative and nonablative applications for neurological and psychiatric diseases.

Abstract

Importance  Magnetic resonance imaging–guided focused ultrasound ablation has been approved for the treatment of refractory essential tremor and is being studied for other neurological indications, including dyskinesias and tremor in Parkinson disease, dystonia, neuropathic pain, obsessive-compulsive disorder, epilepsy, and brain tumors.

Objective  To review the scientific foundations of FUS technology, existing neurological applications, and future advances.

Evidence Review  PubMed was searched for the past 10 years using the terms “transcranial ultrasound,” “focused ultrasound,” and “neurological applications.” Relevant references were selected from the author's reference collection. From the 2855 unique records, 243 publications were screened. After excluding abstracts detailing in vitro studies or non-neurological applications, 86 full texts were retrieved for qualitative review.

Findings  Advances in the transducer design and electronic phase correction have allowed efficient focusing of ultrasounds for transcranial treatment. The mid-frequency (650 kHz) transducer can make small (4-6 mm in diameter) and precise (accuracy of <2 mm) brain lesions. The treatment monitoring is achieved via “live” anatomical thermography imaging and clinical feedback. The initial results from its clinical application in movement disorders are encouraging. Emerging applications in epilepsy and neurobehavioral and cognitive disorders are being explored. The low-frequency (220 kHz) transducer coupled with microbubbles can potentially enable targeted drug delivery for novel applications, such as Alzheimer disease and brain tumors. Finally, neuromodulation with subthreshold sonications may allow the interrogation of brain areas previously not accessible for electrical stimulation.

Conclusions and Relevance  Transcranial focused ultrasound for both ablative and nonablative applications is noninvasive, making it suitable for selected patients who are not candidates for conventional surgical options. Future advancements in imaging and sonication algorithms will improve the safety and efficacy of this technology.

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Source 

jamanetwork