Considerable progress in human brai

Considerable progress in human brain HIFU was madein the 1950s by the Fry brothers, who developed a 4-beamtechnology and demonstrated the therapeutic potential of FUSfor treating neurological disorders by creating lesions deep insidea primate brain (4). Although these advances demonstratedthe great potential of HIFU for treating diverse neurological diseases, successful clinical application would require realtime imaging to accurately visualize and verify target location.To this end, a multi-element phased-array system (Figure 1)was combined with magnetic resonance imaging (MRI), thusallowing for MR-guided FUS (MRgFUS) (5–7). Starting within vitro studies in 1998, this technique permitted simultaneousvisualization of anatomical and temperature maps and providedthe feedback needed to perform a completely incisionless andclosed-loop procedure.In 1998, Hynynen and Jolesz (8) reported using pretreatmentcomputed tomography (CT) scans to inform a phased-arrayHIFU system with phase-correction methods to further mitigateskull attenuation by tightening the focus, thereby increasingthe energy deposition density. This approach led to Food andDrug Administration (FDA)–approved MRgFUS system thatuses thermoablation to treat essential tremor (ET) and tremordominant Parkinson’s disease (PD) in 2016, and more recentlyFDA approved thermoablation of internal globus pallidus,pallidotomy, as an alternative MRgFUS treatment for PDdyskinesia in November 2021. Research to expand the clinicalapplication of FUS technology to other neurological disorders hassince increased greatly (Figure 2).