Semi‐automated generation of individual computational models of the human head and torso from MR images

Kalloch, Benjamin; Bode, J.; Kozlov, Mikhail V.; Pampel, André; Hlawitschka, Mario; Sehm, Bernhard; Villringer, Arno; Möller, Harald E.; Bazin, Pierre‐Louis

doi:10.1002/mrm.27508

Cited by 10 publications

(9 citation statements)

References 47 publications

(71 reference statements)

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“…Due to an inconsistent estimation of the skull thickness, we pursued an alternative approach uncoupled from mri2mesh for the segmentation of the scalp, skull and CSF for all subjects. A multi-atlas-based approach was employed which computed a head segmentation in a majority voting process (Kalloch et al, 2019), resulting in a more robust representation of the thickness of the skull and CSF. Aside from this change in the segmentation routines, any further processing was done utilizing the SimNIBS mri2mesh pipeline again.…”

Section: Methodsmentioning

confidence: 99%

Anodal Transcranial Direct Current Stimulation Over S1 Differentially Modulates Proprioceptive Accuracy in Young and Old Adults

Muffel

Kirsch

Shih

et al. 2019

Front. Aging Neurosci.

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Background: Proprioception is a prerequisite for successful motor control but declines throughout the lifespan. Brain stimulation techniques such as anodal transcranial direct current stimulation (a-tDCS) are capable of enhancing sensorimotor performance across different tasks and age groups. Despite such growing evidence for a restorative potential of tDCS, its impact on proprioceptive accuracy has not been studied in detail yet. Objective: This study investigated online effects of a-tDCS over S1 on proprioceptive accuracy in young (YA) and old healthy adults (OA). Methods: The effect of 15 min of a-tDCS vs. sham on proprioceptive accuracy was assessed in a cross-over, double blind experiment in both age groups. Performance changes were tested using an arm position matching task in a robotic environment. Electrical field (EF) strengths in the target area S1 and control areas were assessed based on individualized simulations. Results: a-tDCS elicited differential changes in proprioceptive accuracy and EF strengths in the two groups: while YA showed a slight improvement, OA exhibited a decrease in performance during a-tDCS. Stronger EF were induced in target S1 and control areas in the YA group. However, no relationship between EF strength and performance change was found. Conclusion: a-tDCS over S1 elicits opposing effects on proprioceptive accuracy as a function of age, a result that is important for future studies investigating the restorative potential of a-tDCS in healthy aging and in the rehabilitation of neurological diseases that occur at advanced age. Modeling approaches could help elucidate the relationship between tDCS protocols, brain structure and performance modulation.

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Section: Methodsmentioning

confidence: 99%

Anodal Transcranial Direct Current Stimulation Over S1 Differentially Modulates Proprioceptive Accuracy in Young and Old Adults

Muffel

Kirsch

Shih

et al. 2019

Front. Aging Neurosci.

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“…In our approach, we segment the scalp, the skull, the air-filled sinuses of the skull, the subarachnoid CSF, the CSF in the ventricles, the gray matter (GM) and the white matter (WM) only from T1-weighted MRI data. The involved segmentation process is described in our previous work [23]. In short, we rely on robust, atlasbased segmentation techniques and image-processing capabilities implemented in JIST, a plugin of MIPAV.…”

Section: Set-up Of the Volume Conductor Modelmentioning

confidence: 99%

A flexible workflow for simulating transcranial electric stimulation in healthy and lesioned brains

et al. 2020

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Simulating transcranial electric stimulation is actively researched as knowledge about the distribution of the electrical field is decisive for understanding the variability in the elicited stimulation effect. Several software pipelines comprehensively solve this task in an automated manner for standard use-cases. However, simulations for non-standard applications such as uncommon electrode shapes or the creation of head models from non-optimized T1-weighted imaging data and the inclusion of irregular structures are more difficult to accomplish. We address these limitations and suggest a comprehensive workflow to simulate transcranial electric stimulation based on open-source tools. The workflow covers the head model creation from MRI data, the electrode modeling, the modeling of anisotropic conductivity behavior of the white matter, the numerical simulation and visualization. Skin, skull, air cavities, cerebrospinal fluid, white matter, and gray matter are segmented semiautomatically from T1-weighted MR images. Electrodes of arbitrary number and shape can be modeled. The meshing of the head model is implemented in a way to preserve the feature edges of the electrodes and is free of topological restrictions of the considered structures of the head model. White matter anisotropy can be computed from diffusion-tensor imaging data. Our solver application was verified analytically and by contrasting the tDCS simulation results with that of other simulation pipelines (SimNIBS 3.0, ROAST 3.0). An agreement in both cases underlines the validity of our workflow. Our suggested solutions facilitate investigations of irregular structures in patients (e.g. lesions, implants) or new electrode types. For a coupled use of the described workflow, we provide documentation and disclose the full source code of the developed tools.

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“…We previously introduced a semi-automatic processing pipeline to generate individualized surface-based models of the human head and upper torso from the MR images of individual subjects [29]. A key feature of this workflow is that the resulting models have a single surface between adjacent structures.…”

Section: Introductionmentioning

confidence: 99%

Patient-Specific RF Safety Assessment in MRI: Progress in Creating Surface-Based Human Head and Shoulder Models

Kozlov

Kalloch

Horner

et al. 2019

Brain and Human Body Modeling

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Semi‐automated generation of individual computational models of the human head and torso from MR images

Cited by 10 publications

References 47 publications

Anodal Transcranial Direct Current Stimulation Over S1 Differentially Modulates Proprioceptive Accuracy in Young and Old Adults

Anodal Transcranial Direct Current Stimulation Over S1 Differentially Modulates Proprioceptive Accuracy in Young and Old Adults

A flexible workflow for simulating transcranial electric stimulation in healthy and lesioned brains

Patient-Specific RF Safety Assessment in MRI: Progress in Creating Surface-Based Human Head and Shoulder Models

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