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DTI Indices and Tractography in Evaluating Treatment Efficacy in FUS on Essential Tremor

Poster No:

91 

Submission Type:

Abstract Submission 

Authors:

Yan-Hua Su1,2, Shin Tai Chong3, Cheng-Chia Lee4, Ching-Po Lin5,6

Institutions:

1National yang ming chiao tung university, Taipei City, Beitou Dist., 2Division of Neurosurgery, Department of Surgery, Fu Jen Catholic University Hospital, New Taipei City, Taiwan, 3Institute of Neuroscience, National Yang Ming Chiao Tung University, Taiepi, Taiwan, 4Taipei Veteran General Hospital, Taipei, Taiwan, 5Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei, Taiwan, 6Department of Education and Research, Taipei City Hospital, Taipei, Taiwan

First Author:

Yan-Hua Su  
National yang ming chiao tung university|Division of Neurosurgery, Department of Surgery, Fu Jen Catholic University Hospital
Taipei City, Beitou Dist.|New Taipei City, Taiwan

Co-Author(s):

Shin Tai Chong  
Institute of Neuroscience, National Yang Ming Chiao Tung University
Taiepi, Taiwan
Cheng-Chia Lee  
Taipei Veteran General Hospital
Taipei, Taiwan
Ching-Po Lin  
Institute of Neuroscience, National Yang Ming Chiao Tung University|Department of Education and Research, Taipei City Hospital
Taipei, Taiwan|Taipei, Taiwan

Introduction:

Essential Tremor (ET) is a prevalent movement disorder characterized by involuntary rhythmic tremors. [1] The Dentate tract (DRTT) plays a crucial role in modulating movement[2]. The DRTT consists of two portions: the decussating DRTT (dDRTT), the more prominent one, crosses the midline to the contralateral red nucleus and thalamus[3]; the less prevalent non-decussating DRT (ndDRTT) proceeds ipsilaterally from the dentate nucleus to the red nucleus and thalamus. Focused Ultrasound (FUS) is a non-invasive method gaining popularity for treating movement disorders, including ET, by precisely targeting the DRT to alleviate symptoms. Currently, there is still no radiological parameter to predict the outcome after MRgFUS. We plan to apply MRI techniques, including Diffusion Tensor Imaging (DTI), to reconstruct the corticospinal tract (CST), dDRTT and ndDRTT and investigate changes in the tract after FUS treatment in ET patients. We aim to correlate the changes in the DRT with the treatment outcome

Methods:

Seven patients diagnosed with ET were enrolled in the study. Pre-treatment, post-treatment, and 3 months post-treatment TETRAS scores (The Essential Tremor Rating Assessment Scale) were measured. All patients underwent 3T magnetic resonance imaging for high resolution T1-weighted image (T1w) and diffusion-weighted images (DWI). All images were pre-processed with iDIO package[5]. We used generalized q-sampling imaging inDSI-Studio for fiber tracking. Whole brain deterministic fiber tracking with 100,000 seeds were used, the CST, nd-DRTT, and dDRTT were reconstructed with the following related region of interest: primary motor area, red nucleus, dentate nucleus, and spinal cord. ( Figure 1) All images were registered to the pre-treatment images for extracting all diffusion indices along each fiber tracts (only target on treatment field of view). Finally, we then used the paired T-tests to compare Fractional Anisotropy (FA), Radial Diffusivity (RD), Mean Diffusivity (MD), and Axial Diffusivity (AD) before treatment, immediately after treatment, and 3 months later at the lesion site.[5]
Supporting Image: Figure1.png
   ·Demonstration of CST, dDRTT and ndDRTT. The indice was measure over the lesion site where focus ultrasound produce lesion.
 

Results:

The average TETRAS score was 23.6 points preoperatively, 17.8 points immediately after MRgFUS, and 12.8 points 3 months after MRgFUS. No significant side effects were noted after MRgFUS. In the treatment side DTI analysis, we performed three groups of paired T-tests (Group 1: pre-treatment vs post-treatment, Group 2: pre-treatment vs 3 months follow-up, Group 3: post-treatment vs 3 months follow-up). We found a decrease in FA of the corticospinal tract (CST), a decrease in FA, and an increase in RD in dDRT, and a decrease in FA in ndDRT in Group 1. In Group 2, we found a decrease in FA in CST, a decrease in AD in dDRT, and ndDRT. In Group 3, we discovered an increase in FA in CST, an increase in FA, and a decrease in RD and MD in dDRT; an increase in FA and a decrease in MD in ndDRT. Figure 2 showed the change of dDRTT in pre-treatment, post treatment and 3 months follow up.
Supporting Image: Figure2.png
   ·Figure 2.A-D shows changes of AD, FA, MD and RD of dDRTT in pre-treatment (blue), post-treatment (orange) and 3 months follow up (grey). Figure 2A showed significance decrease of AD in 3 months follow
 

Conclusions:

There is a significant improvement in TETRAS after MRgFUS treatment, with further tremor improvement observed 3 months later. The changes in FA could indicate microstructural changes after FUS, observable in CST, dDRT, and ndDRT. However, the changes in RD and AD observed in dDRT and ndDRT could serve as MRI evidence of tract destruction after MRgFUS, suggesting that RD and AD in dDRT and ndDRT could serve as MRI markers for ET patients.

Brain Stimulation:

Sonic/Ultrasound 1

Neuroanatomy, Physiology, Metabolism and Neurotransmission:

White Matter Anatomy, Fiber Pathways and Connectivity 2

Keywords:

WHITE MATTER IMAGING - DTI, HARDI, DSI, ETC
Other - essential tremor, MRgFUS

1|2Indicates the priority used for review

Provide references using author date format

1. Ferreira JJ et al. 2010: How common is the most common adult movement disorder? Update on the worldwide prevalence of essential tremor. Movement Disorders 2010, 25(5):534-541.
2. Reinacher PC et al. 2020: The dentato-rubro-thalamic tract as the potential common deep brain stimulation target for tremor of various origin: an observational case series. Acta Neurochirurgica 2020, 162:1053-1066.
3. Fernandez-Miranda JC et al. 2016: The nondecussating pathway of the dentatorubrothalamic tract in humans: human connectome-based tractographic study and microdissection validation. Journal of neurosurgery 2016, 124(5):1406-1412
4. Heinsen H et al. 2021: Use of computational fluid dynamics for 3D fiber tract visualization on human high thickness histological slices: histological mesh tractography. Brain Structure and Function 2021, 226:323-333.
5. Lin CP et al. 2023: Integrated diffusion image operator (iDIO): A pipeline for automated configuration and processing of diffusion MRI data. In.: Wiley Online Library; 2023.