1167 Personalized Tremor Control Targeting for MRgFUS Using Tractography

INTRODUCTION: The use of tractography as a clinical and research tool is increasingly growing, and presents promising results for targeting and improvement of neuromodulation procedures outcomes. However, tractography suffers from several limitations and lack of standardization while validation in cadavers is complex and limited. Magnetic Resonance guided Focused Ultrasound Surgery (MRgFUS) is a well-established non-invasive technology that induce a focal thermal lesion with sub-millimeter precision to treat patients with tremor. The ventral intermediate nucleus of the thalamus (VIM) is a well-studied target for tremor reduction, however, can't be visualized radiologically. Indirect targeting is the most common approach for VIM targeting based on patients' anatomy. Nevertheless, it correlates with suboptimal tremor control up to 20% with inconsistency of the treatment's outcome, such as long-term tremor control and side effects. METHODS: Pre- and postoperative MRI scans were acquired from 81 patients who underwent MRgFUS. Using the preoperative scan, three tracts (pyramidal tract [PT], medial lemniscus [ML], and dentatorubrothalamic tract [DRT]) were located for each patient using tractography, while utilizing a-priori anatomical knowledge. Day one postoperative T1 weighted images were used for lesion evaluation. Advanced analysis was applied to find correlations between the postoperative clinical outcome (up to 2 years) and the image analysis. RESULTS: A specific segmented region of the DRT with respect to the PT and ML was correlated with superior outcomes, and personalized optimal targeting coordinates were determined based on these results. CONCLUSIONS: These results imply the existence of sweet spot within the DRT. The tractography and analysis approach yielded reliable results while using scans acquired in clinical conditions. This approach can be used as a tool for personal identification of the tremor and improvement of clinical results.