Department of Neurosurgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
Department of Neurosurgery, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY, USA.
Neuroimage Clin. 2024;41:103587. doi: 10.1016/j.nicl.2024.103587. Epub 2024 Feb 27.
Deep brain stimulation (DBS) studies have shown that stimulation of the motor segment of the thalamus based on probabilistic tractography is predictive of improvement in essential tremor (ET). However, probabilistic methods are computationally demanding, requiring the need for alternative tractography methods for use in the clinical setting. The purpose of this study was to compare probabilistic vs deterministic tractography methods for connectivity-based targeting in patients with ET.
Probabilistic and deterministic tractography methods were retrospectively applied to diffusion-weighted data sets in 36 patients with refractory ET. The thalamus and precentral gyrus were selected as regions of interest and fiber tracking was performed between these regions to produce connectivity-based thalamic segmentations, per prior methods. The resultant deterministic target maps were compared with those of thresholded probabilistic maps. The center of gravity (CG) of each connectivity map was determined and the differences in spatial distribution between the tractography methods were characterized. Furthermore, the intersection between the connectivity maps and CGs with the therapeutic volume of tissue activated (VTA) was calculated. A mixed linear model was then used to assess clinical improvement in tremor with volume of overlap.
Both tractography methods delineated the region of the thalamus with connectivity to the precentral gyrus to be within the posterolateral aspect of the thalamus. The average CG of deterministic maps was more medial-posterior in both the left (3.7 ± 1.3 mm) and the right (3.5 ± 2.2 mm) hemispheres when compared to 30 %-thresholded probabilistic maps. Mixed linear model showed that the volume of overlap between CGs of deterministic and probabilistic targeting maps and therapeutic VTAs were significant predictors of clinical improvement.
Deterministic tractography can reconstruct DBS thalamic target maps in approximately 5 min comparable to those produced by probabilistic methods that require > 12 h to generate. Despite differences in CG between the methods, both deterministic-based and probabilistic targeting were predictive of clinical improvement in ET.
深部脑刺激（DBS）研究表明，基于概率示踪的丘脑运动节段刺激可预测原发性震颤（ET）的改善。然而，概率方法计算量很大，需要替代示踪方法用于临床环境。本研究旨在比较基于 ET 患者连接性的概率与确定性示踪方法。
回顾性地将概率和确定性示踪方法应用于 36 例难治性 ET 患者的弥散加权数据集。选择丘脑和中央前回作为感兴趣区，并在这些区域之间进行纤维追踪，以产生基于连接性的丘脑节段化，如先前的方法所示。将得到的确定性目标图与阈值概率图进行比较。确定每个连接图的重心（CG），并描述示踪方法之间的空间分布差异。此外，还计算了连接图和 CG 与治疗性组织激活体积（VTA）之间的交集。然后使用混合线性模型评估重叠体积与震颤改善的关系。
两种示踪方法都描绘了与中央前回有连接的丘脑区域，位于丘脑的后外侧。与 30%-阈值概率图相比，左（3.7±1.3mm）和右（3.5±2.2mm）半球的确定性图谱的平均 CG 更靠中后。混合线性模型显示，CG 与治疗性 VTAs 的确定性和概率靶向图之间的重叠体积是临床改善的显著预测因素。
与需要超过 12 小时生成的概率方法相比，确定性示踪可以在大约 5 分钟内重建 DBS 丘脑目标图。尽管两种方法的 CG 存在差异，但基于确定性和概率的靶向治疗都可预测 ET 的临床改善。
