Transcranial Magnetic Stimulation-coil design with improved focality

Rastogi, Priyam; Lee, Erik; Hadimani, Ravi L.; Jiles, David

doi:10.1063/1.4973604

Cited by 48 publications

(40 citation statements)

References 18 publications

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“…Fig.1 has illustrated the distance of 5 mm from the surface of each coil to the scalp. To illustrate and compare the results of each set of simulations, two metrics, E-Max (the maximum E-field intensity in the cerebellum, we used mean value from the voxels with the largest 100 values) and V-Half (the volume of the cerebellum exposed to E-field intensities at least half E-Max), were employed [16].…”

Section: Methodsmentioning

confidence: 99%

Investigating the Role of Coil Designs and Anatomical Variations in Cerebellar TMS

et al. 2019

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Transcranial magnetic stimulation (TMS) is a non-invasive neuromodulation technique that is used for treating various neurological disorders such as major depressive disorder. TMS has been gaining popularity in the field of neurostimulation of the cerebellum, since the cerebellum is a complex structure connected with almost the entire central nervous system and TMS has promise for non-invasively probing cerebellar function. Recent studies have discovered that the cerebellum plays an important role not only in motor planning and behavior but also in the cognitive domain. However, few studies have explored how different coil designs and anatomical variations affect the effectiveness of cerebellar TMS. Therefore, in this paper, we investigated the effects of cerebellar TMS with different coil designs positioning on several locations. Finite-element modeling was conducted with Figure-8 coil and D-B80 coil. Each coil was positioned in the center, 1 and 3 cm to the left of center of the cerebellum, and all the locations were tangential to the scalp at a distance of 5 mm. Furthermore, 50 MRI derived head models were used in the computer modeling to examine how anatomical variations affect the distribution and intensity of electric field in cerebellar TMS.

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Section: Methodsmentioning

confidence: 99%

Investigating the Role of Coil Designs and Anatomical Variations in Cerebellar TMS

et al. 2019

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“…The linear inequality constraint on the second line of Eq. (19) ensures that energy is bounded from above by ̃. We replace each quadratic constraint of the form λ 2 ≤ with Δ linear ones.…”

Section: Mixed Integer Linear Programming Algorithm For Finding Optimmentioning

confidence: 99%

Design of Transcranial Magnetic Stimulation Coils with Optimal Trade-off between Depth, Focality, and Energy

Gomez

Goetz

Peterchev

2018

Preprint

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DECLARATION OF INTERESTThe fdTMS technology described in this paper is subject to a provisional patent application by Duke University with the authors as inventors. Additionally: L.J.G. is inventor on a patent pertaining to the design of focal multicoil TMS systems. S.M.G. is inventor on patents and patent applications; he has received royalties from Rogue Research, TU Muenchen, and Porsche; furthermore, he has been provided with research support and patent fee reimbursement from Magstim Co. A.V.P. is inventor on patents and patent applications, and has received research and travel support as well as patent royalties from Rogue Research; research and travel support, consulting fees, as well as equipment loan from Tal Medical / Neurex; patent application and research support from Magstim; and equipment loans from MagVenture, all related to technology for transcranial magnetic stimulation. ABSTRACTBackground: Transcranial magnetic stimulation (TMS) is a noninvasive brain stimulation technique used for research and clinical applications. Existent TMS coils are limited in their precision of spatial targeting (focality), especially for deeper targets.Objective: This paper presents a methodology for designing TMS coils to achieve optimal trade-off between the depth and focality of the induced electric field (E-field), as well as the energy required by the coil. Methods:A multi-objective optimization technique is used for computationally designing TMS coils that achieve optimal trade-offs between stimulation focality, depth, and energy (fdTMS coils). The fdTMS coil winding(s) maximize focality (minimize stimulated volume) while reaching a target at a specified depth and not exceeding predefined peak E-field strength and required coil energy. Spherical and MRI-derived head models are used to compute the fundamental depth-focality trade-off as well as focality-energy tradeoffs for specific target depths.Results: Across stimulation target depths of 1.0-3.4 cm from the brain surface, the stimulated volume can be theoretically decreased by 42%-55% compared to existing TMS coil designs. The stimulated volume of a figure-8 coil can be decreased by 36%, 44%, or 46%, for matched, doubled, or quadrupled energy. For matched focality and energy, the depth of a figure-8 coil can be increased by 22%. Conclusion:Computational design of TMS coils could enable more selective targeting of the induced Efield. The presented results appear to be the first significant advancement in the depth-focality trade-off of TMS coils since the introduction of the figure-8 coil three decades ago, and likely represent the fundamental physical limit.

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“…Also, electric fields induced by TMS decrease rapidly with distance (inversely varies as cube of distance), and hence their effect is generally limited to the surface of cerebral cortex, cerebellum, and spinal cord structures. Stimulation in smaller and deeper regions of brain is typically challenging to achieve, and literature exists showing promise for deeper penetration and focality of fields with better coil designs 11,12,13,14 . These coil designs must thoroughly be tested to ascertain their viability for either mice or human clinical trials, making numerical simulations and interactive visualization a necessary prior step in advancing their development.…”

Section: Why Are Simulations Of Tms Necessary?mentioning

confidence: 99%

Real-time visualization of magnetic flux densities for transcranial magnetic stimulation on commodity and fully immersive VR systems

2017

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Transcranial Magnetic Stimulation (TMS) is a non-invasive procedure that uses time varying short pulses of magnetic fields to stimulate nerve cells in the brain. In this method, a magnetic field generator ("TMS coil") produces small electric fields in the region of the brain via electromagnetic induction. This technique can be used to excite or inhibit firing of neurons, which can then be used for treatment of various neurological disorders such as Parkinson's disease, stroke, migraine, and depression. It is however challenging to focus the induced electric field from TMS coils to smaller regions of the brain. Since electric and magnetic fields are governed by laws of electromagnetism, it is possible to numerically simulate and visualize these fields to accurately determine the site of maximum stimulation and also to develop TMS coils that can focus the fields on the targeted regions. However, current software to compute and visualize these fields are not real-time and can work for only one position/orientation of TMS coil, severely limiting their usage. This paper describes the development of an application that computes magnetic flux densities (h-fields) and visualizes their distribution for different TMS coil position/orientations in real-time using GPU shaders. The application is developed for desktop, commodity VR (HTC Vive), and fully immersive VR CAVETM systems, for use by researchers, scientists, and medical professionals to quickly and effectively view the distribution of h-fields from MRI brain scans.

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Transcranial Magnetic Stimulation-coil design with improved focality

Cited by 48 publications

References 18 publications

Investigating the Role of Coil Designs and Anatomical Variations in Cerebellar TMS

Investigating the Role of Coil Designs and Anatomical Variations in Cerebellar TMS

Design of Transcranial Magnetic Stimulation Coils with Optimal Trade-off between Depth, Focality, and Energy

Real-time visualization of magnetic flux densities for transcranial magnetic stimulation on commodity and fully immersive VR systems

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