probabilistic_tractography [Neurosurgery Wiki]

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The goal of probabilistic [[tractography]] is to obtain a connectivity index along with a [[white matter]] [[pathway]] that reflects [[fiber]] organization and is sensitive to pathological abnormalities contributing to disability.
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Krishna et al., [[prospective]]ly assessed the [[outcome]]s of [[Focused ultrasound thalamotomy]] (FUS-T) in 10  [[essential tremor]] (ET) patients using [[tractography]]-based [[target]]ing of the [[ventral intermediate nucleus]] ([[VIM]]).

VIM was identified at the [[intercommissural]] plane based on its neighboring [[tract]]s: the [[pyramidal tract]] and [[medial lemniscus]]. FUS-T was performed at the center of tractography-defined VIM. [[Tremor]] outcomes, at baseline and 3 months, were assessed independently by the [[Tremor Research Group]]. They analyzed targeting [[coordinate]]s, clinical [[outcome]]s, and [[adverse event]]s. The FUS-T lesion location was analyzed in relation to unbiased thalamic parcellation using [[probabilistic tractography]]. Quantitative [[diffusion weighted imaging]] changes were also studied in [[fiber tract]]s of interest.

The [[tractography]] [[coordinate]]s were more anterior than the standard. Intraoperatively, therapeutic [[sonication]]s at the tractography target improved tremor (>50% improvement) without motor or sensory side effects. Sustained [[improvement]] in tremor was observed at 3 mo (tremor score: 18.3 ± 6.9 vs 8.1 ± 4.4, P = .001). No motor weakness and sensory deficits after FUS-T were observed during 6-mo follow-up. [[Ataxia]] was observed in 3 patients. FUS-T lesions overlapped with the VIM parcellated with probablisitic tractography. Significant microstructural changes were observed in the [[white matter]] connecting VIM with [[cerebellum]] and [[motor cortex]].

This is the first report of prospective [[VIM targeting]] with tractography for FUS-T. These results suggest that tractography-guided targeting is safe and has satisfactory short-term clinical outcomes
((Krishna V, Sammartino F, Agrawal P, Changizi BK, Bourekas E, Knopp MV, Rezai
A. Prospective Tractography-Based Targeting for Improved Safety of Focused
Ultrasound Thalamotomy. Neurosurgery. 2019 Jan 1;84(1):160-168. doi:
10.1093/neuros/nyy020. PubMed PMID: 29579287.
)).