Date of Thesis

Spring 2025

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Description

Introduction

Deep brain stimulation (DBS) of the ventral intermediate (VIM) nucleus of the thalamus is a proven treatment for essential tremor (ET). Neurosurgeons rely on thalamic atlases to locate relevant nuclei for stimulation; however, many atlases are available, with different divisions of motor and sensory subnuclei. Segmenting anatomical targets using diffusion tensor imaging (DTI) offers a patient-specific alternative to traditional atlas-based approaches. This work compares the effectiveness of multiple atlases and segmentation techniques in defining motor and sensory subnuclei, evaluated based on the correspondence of clinical outcomes with tissue activation models of an ET patient dataset.

Objective

This research investigates the differences between thalamic atlases, how segmentation techniques are used to parcellate patient thalami, and the clinical correspondence of various atlases and segmentation techniques to determine the relative effectiveness of atlases in defining the motor and sensory subnuclei. Materials and Methods 22 ET patients who underwent unilateral VIM DBS were analyzed retrospectively. Six prominent thalamic atlases were obtained from LEAD-DBS. The atlases segmented the patient thalami in two ways: atlas-based segmentation (ABS) used the atlas to determine subnuclei divisions, and DTI-based segmentation (DTIBS) incorporated tissue properties to create clusters of subnuclei.

Results

High motor and low sensory activation are expected for tremor reduction stimulation, and ABS produced this trend across all atlases, whereas DTIBS produced this trend in only half of the atlases. Greater sensory stimulation is expected for paresthesia outcomes compared to tremor reduction outcomes, and ABS yielded this trend in almost all atlases, whereas DTIBS yielded this trend in only half of the atlases. ABS was more generalizable than DTIBS across atlases. The Jakab atlas was the only atlas to show the expected motor and sensory stimulation trend associated with each clinical outcome when using either ABS or DTIBS, making it the most clinically accurate atlas investigated.

Significance

This work presents an analysis of six prominent atlases that are used for indirect targeting of the VIM thalamus for DBS. The findings of this study may be used to inform the choice of atlas and segmentation approach used in surgical planning for DBS lead localization.

Keywords

Deep Brain Stimulation, Essential Tremor, Diffusion Tensor Imaging, Thalamic Segmentation, Thalamic Atlas

Access Type

Honors Thesis (Bucknell Access Only)

Degree Type

Bachelor of Science in Biomedical Engineering

Major

Biomedical Engineering

Minor, Emphasis, or Concentration

Russian Studies

First Advisor

Karlo A. Malaga

Second Advisor

James W. Baish

Third Advisor

Keegan Kang

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