MR Guided Focused Ultrasound Neuromodulation
Li Min Chen1, William A Grissom2, and Charles F Caskey3
1Vanderbilt University, TN, United States, 2Biomedical Engineering, Vanderbilt University, Nashville, TN, United States, 3Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, United States

Synopsis

Transcranial focused ultrasound (tFUS) is an emerging technology that has ablative and nonablative applications for neurological and psychiatric diseases. As a neuromodulation tool, tFUS offers high precision targeting, stimulation of deep brain structures, and focal drug or gene delivery via blood-brain barrier opening (BBBO). MR-acoustic radiation force imaging (MR-ARFI) and functional MRI (fMRI) add capabilities of real-time feedback on tFUS beam location and functional monitoring of FUS in action. Advanced MRI contrasts provide tFUS safety assessment. In this talk, I will review these methods and discuss how they are applied to modulate brain function in humans and animals.

Complementing MRI with Other Modalities: Hardware & Method Development

Today, there are three major applications for FUS in the brain, each of which dictates different system designs. The first is ablation in which brain tissue is destroyed thermally. MRI-guided FUS ablation has been FDA approved in the US for treatment of refractory essential tremor and is being studies for other neurological indications, including dyskinesias and tremor in Parkinson disease, dystonia, neuropathic pain, obsessive-compulsive disorder, epilepsy, and brain tumors. In this application, relatively short, high power sonications are applied to rapidly raise the tissuetemperature with a very tight focus, but cavitation is avoided. MRI temperature mapping provides localization feedback of the FUS ablation target. The second application is neuromodulation, in which low-pressure FUS isapplied to inhibit or excite neurons, and both thermal rises and cavitation are to be avoided. In this application, MR-acoustic radiation force imaging (MR-ARFI) and functional MRI (fMRI) add capabilities of real-time feedback on tFUS beam location and functional monitoring of FUS in action. The third is BBB opening using FUS and microbubbles,and the first clinical trials in using this for delivering therapeutic agents in the brain for Alzheimers are underway. Inthis application, a wider focus is tolerated to enable off-center brain steering, and cavitation is actually used tomonitor treatment. Advanced MRI contrast such DCE can provide safety assessments after FUS application. In thistalk, I will discuss these applications

Acknowledgements

NIH U18 EB029351, R01MH111877, R24MH109105, 1S10OD012297-01A1, 5T32EB014841, and 1F31EB026928, and the Focused Ultrasound Foundation.

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Proc. Intl. Soc. Mag. Reson. Med. 30 (2022)