Speakers

Differential tractography as a track-based biomarker for focused ultrasound thalamotomy
1110 10:10-10:20
Functional Neurosurgery & Epilepsy/304A
Objective: Magnetic resonance imaging-guided focused ultrasound (MRgFUS) has emerged as a promising treatment option for essential tremor (ET) and tremor-dominant Parkinson's disease (TDPD). Although it has the best precise targeting method, unfavorable long-term responders were still noted. The need for precise targeting and objective quantification of image metrics and their correlation with clinical response remained unclear. In our study, we proposed delineating the dentorubrothalamic tract (DRTT) and measuring the change of diffuse tensor imaging (DTI) metrics between long-term responders and short-term responders. Material and Method: We retrospectively reviewed the patients with ET or TDPD who underwent MRgFUS thalamotomy from 2020 to 2024. Every patient underwent pre-treatment and post-treatment MRI scans. We used DSI studio to identify the white matter tracts with major changes in the DTI metrics (fractional anisotropy (FA), quantitative anisotropy (QA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD)) inside the thalamus on the treatment side. The Clinical Rating Tremor Scale (CRST) reduction was measured in each patient at the time of pre-treatment, one day post-treatment, and 3 months post-treatment. Correlation of tremor reduction and DTI metrics change was performed. Result: Thirty-eight patients were included in the study. Five patients were defined as short-term responders, who had tremor reduction greater than 50% immediately after treatment but had tremor relapse greater than 50% at 3-month follow-up after treatment.CRST reduction >50% on the day after treatment. There was a significantly greater major QA and FA change between pre-treatment and one-day post-treatment scans in DTI metrics, including tract number and tract volume of DRTT in long-term responders. Conclusion: Differential tractography and its measurement of DTI metrics immediately after MRgFUS thalamotomy could be a predictor of long-term tremor reduction. Further investigation of the correlation between the extent of tremor reduction and DTI metrics change is needed.