Objectives: Navigated transcranial magnetic stimulation (nTMS) provides significant benefits over classic TMS. Yet, the acquisition of individual structural magnetic resonance images (MRIindividual) is a time-consuming, expensive, and not feasible prerequisite in all subjects for spatial tracking and anatomical guidance in nTMS studies. We hypothesize that spatial transformation can be used to adjust MRI templates to individual head shapes (MRIwarped) and that TMS parameters do not differ between nTMS using MRIindividual or MRIwarped. Materials and Methods: Twenty identical TMS sessions, each including four different navigation conditions, were conducted in 10 healthy subjects (one female, 27.4 ± 3.8 years), i.e., twice per subject by two researchers to additionally assess interrater reliabilities. MRIindividual were acquired for all subjects. MRIwarped were obtained through the spatial transformation of a template MRI following a 5-, 9-and 36-point head surface registration (MRIwarped_5, MRIwarped_9, MRIwarped_36). Stimulation hotspot locations, resting motor threshold (RMT), 500 μV motor threshold (500 μV-MT), and mean absolute motor evoked potential difference (MAD) of primary motor cortex (M1) examinations were compared between nTMS using either MRIwarped variants or MRIindividual and non-navigated TMS. Results: M1 hotspots were spatially consistent between MRIindividual and MRIwarped_36 (insignificant deviation by 4.79 ± 2.62 mm). MEP thresholds and variance were also equivalent between MRIindividual and MRIwarped_36 with mean differences of RMT by −0.05 ± 2.28% maximum stimulator output (%MSO; t(19) = −0.09, p = 0.923), 500 μV-MT by −0.15 ± 1.63%MSO (t(19) = −0.41, p = 0.686) and MAD by 70.5 ± 214.38 μV (t(19) = 1.47, p = 0.158). Intraclass correlations (ICC) of motor thresholds were between 0.88 and 0.97. Conclusions: NTMS examinations of M1 yield equivalent topographical and functional results using MRIindividual and MRIwarped if a sufficient number of registration points are used.

中文翻译：

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在健康受试者的导航 TMS 研究中，个体化模板 MRI 是个体 MRI 的有效且可靠的替代方案

目标：导航经颅磁刺激 (nTMS) 比经典 TMS 具有显着优势。然而，对于 nTMS 研究中的空间跟踪和解剖指导，获取单个结构磁共振图像 (MRIindividual) 是一项耗时、昂贵且不可行的先决条件。我们假设空间变换可用于将 MRI 模板调整为个体头部形状 (MRIwarped)，并且 TMS 参数在使用 MRIindividual 或 MRIwarped 的 nTMS 之间没有差异。材料和方法：在 10 名健康受试者（一名女性，27.4 ± 3.8 岁）中进行了 20 个相同的 TMS 会话，每个会话包括四种不同的导航条件，即由两名研究人员对每个受试者进行两次，以额外评估交互者之间的可靠性。为所有受试者采集了 MRI 个体。MRIwarped 是通过 5、9 和 36 点头部表面配准（MRIwarped_5、MRIwarped_9、MRIwarped_36）后模板 MRI 的空间变换获得的。使用 MRIwarped 变体或 MRIindividual 在 nTMS 之间比较刺激热点位置、静息运动阈值 (RMT)、500 μV 运动阈值 (500 μV-MT) 和初级运动皮层 (M1) 检查的平均绝对运动诱发电位差 (MAD)和非导航 TMS。结果：M1 热点在 MRIindividual 和 MRIwarped_36 之间在空间上是一致的（4.79 ± 2.62 毫米的微小偏差）。MEP 阈值和方差在 MRIindividual 和 MRIwarped_36 之间也相同，RMT 的平均差异为 -0.05 ± 2.28% 最大刺激器输出（%MSO；t(19) = -0.09, p = 0.923），500 μV-MT 为 -0.15 ± 1.63% MSO (t(19) = -0.41, p = 0。686) 和 MAD 为 70.5 ± 214.38 μV (t(19) = 1.47, p = 0.158)。运动阈值的组内相关性 (ICC) 介于 0.88 和 0.97 之间。结论：如果使用足够数量的配准点，使用 MRIindividual 和 MRIwarped 对 M1 的 NTMS 检查产生等效的地形和功能结果。