New Technique for Direct Targeting of the Ventral Intermediate Nucleus Using Magnetic Resonance-Guided Focused Ultrasound

Juan Aibar^1*Rodrigo Akira Watanabe²Nathan McDannold³Garth Rees Cosgrove³

• ¹Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain
• ²Federal University of São Paulo, São Paulo, São Paulo, Brazil
• ³Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States

Background: Accurate targeting and lesion placement are critical in treating movement disorders with magnetic resonance-guided focused ultrasound (MRgFUS). Indirect atlasbased targeting often lacks precision. Direct anatomical targeting with 3T MRI offers a promising alternative. This report aims to refine MRgFUS thalamotomy by integrating advanced imaging and lesion conformality strategies. Material and methods: Preoperative and postoperative white matter null (WMn) MRimaging was employed for direct Vim detection. Essential anatomical landmarks are identified. Dual-lesion conformality was used to adapt to the spatial distribution of the Vim. Results: Lesions of the Vim were identifiable using the postoperative WMn MRI sequence. The direct visualization of the Vim usually avoids extension into the internal capsule and the sensory thalamic nucleus. Sagittal imaging confirmed the dual-lesion conformational strategy which conforms to the antero-superior orientation of the Vim. Conclusions: Direct Vim targeting for MRgFUS is feasible for individual cases with the use of WMnMPRAGE MRI sequences. The use of lesion conformality adapts well to the anatomical and spatial distribution of Vim. Further studies will be needed to confirm the safety profile of this approach and correlate with clinical outcomes. Con formato: Sangría: Primera línea: 0 cm Eliminado: Direct targeting of Vim using WMn MRI 80 sequences is accurate, safe and feasible in a clinical 81 environment. The lesion conformality strategy encompasses 82 the critical Vim volume to reduce long-term tremor 83 recurrences.… Con formato: Fuente: (Predeterminada) Times New Roman, 12 pto Eliminado: MRgFUS is typically performed using indirect, 156 atlas-based coordinates to localize the Vim. The intra-157 operative MRI obtained with the patient in the Insightec FUS 158 treatment helmet is used to identify the anterior commissure 159 (AC) and posterior commissure (PC) and then by selecting a 160 target ¼ distance of the AC/PC length in front of PC and 14 161 mms from the midline. These images provide very limited 162 visualization of the thalamus or its surrounding structures 163 (Figure 1). ¶ 164 Eliminado: improve upon this situation, 165 Con formato: Superíndice Con formato: Inglés (americano)