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  • Reliability of Diffusion-tractography-based Thalamic Segmentation for Identifying Targets for Noninvasive Neuromodulation using MR-guided Focused Ultrasound

    Final Number:

    Angela Elizabeth Downes MD; W. Jeffrey Elias MD; Nader Pouratian MD, PhD

    Study Design:
    Clinical Trial

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2013 Annual Meeting

    Introduction: While noninvasive modalities like MR-guided focused ultrasound and radiosurgery may provide opportunities for neuromodulation, the success and risk profile will ultimately depend on optimizing targeting. Diffusion tractography based thalamic segmentation has previously been shown to be a reliable method for identifying final targets in invasive neuromodulation, namely deep brain stimulation. The objective of this study was to investigate the role of tractography-based thalamic segmentation for noninvasive neuromodulation, evaluating final MRgFUS thalamotomy sites with that predicted by the proposed imaging technique. This analysis has potential significant implications for noninvasive neuromodulation.

    Methods: Fifteen patients with medically refractory essential tremor who underwent MRgFUS generated thalamotomy (ExAblate InSightec) at the University of Virginia Health System were studied. Targeting was performed using indirect targeting methodologies on baseline T1-weighted MR images obtained in all patients. The authors retrospectively performed image analysis for each patient comparing the final thalamotomy location with the predicted optimal site based connectivity-based thalamic segmentation.

    Results: Fifteen unilateral thalamotomies were performed with MRgFUS using indirect targeting. The location of the thalamotomy had a high degree of colocalization to the site predicted by connectivity-based segmentation.

    Conclusions: This report demonstrates the patient-specific reliability of diffusion tractography based thalamic segmentation to predict final target thalamotomies generated by MRgFUS in the treatment of tremor. This imaging technique can be utilized in other noninvasive modalities such as stereotactic radiosurgery to create targets in neuromodulation that are both accurate and precise as well as specific to the patient’s anatomic variations.

    Patient Care: improve targeting in neuromodulation and provide patient specific variations

    Learning Objectives: By the conclusion of this session, participants should be able to 1) describe the importance of precise and accurate targeting in neuromodulation 2) describe a novel imaging method using Diffusion tractography to improve targeting


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