Electric field properties of two commercial figure-8 coils in TMS: calculation of focality and efficiency

Thielscher, Axel; Kammer, Thomas

doi:10.1016/j.clinph.2004.02.019

Cited by 260 publications

(183 citation statements)

References 22 publications

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“…1d) replacing the TMS coil in these measurements represents an axis that is perpendicular to the coil plane and runs through the midpoint of the coil. It corresponds to the peak of the induced electric field (10). The accuracy of coil rotations around this axis was not tested.…”

Section: Coil Positioning Method: Calibration and Validationmentioning

confidence: 99%

New coil positioning method for interleaved transcranial magnetic stimulation (TMS)/functional MRI (fMRI) and its validation in a motor cortex study

Moisa

Pohmann

Ewald³

et al. 2008

Magnetic Resonance Imaging

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Purpose:To develop and test a novel method for coil placement in interleaved transcranial magnetic stimulation (TMS)/functional MRI (fMRI) studies. Materials and Methods:Initially, a desired TMS coil position at the subject's head is recorded using a neuronavigation system. Subsequently, a custom-made holding device is used for coil placement inside the MR scanner. The parameters of the device corresponding to the prerecorded position are automatically determined from a fast structural image acquired directly before the experiment. The spatial accuracy of our method was verified on a phantom. Finally, in a study on five subjects, the coil was placed above the cortical representation of a hand muscle in M1 and the blood oxygenation level-dependent (BOLD) responses to short repetitive TMS (rTMS) trains were assessed using echo-planar imaging (EPI) recordings. Results: :The spatial accuracy of our method is in the range of 2.9 Ϯ 1.3 (SD) mm. Motor cortex stimulation resulted in robust BOLD activations in motor-and auditoryrelated brain areas, with the activation in M1 being localized in the hand knob. Conclusion:We present a user-friendly method for TMS coil positioning in the MR scanner that exhibits good spatial accuracy and speeds up the setup of the experiment. The motor-cortex study proves the viability of the approach and validates our interleaved TMS/fMRI setup.

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Section: Coil Positioning Method: Calibration and Validationmentioning

confidence: 99%

New coil positioning method for interleaved transcranial magnetic stimulation (TMS)/functional MRI (fMRI) and its validation in a motor cortex study

Moisa

Pohmann

Ewald³

et al. 2008

Magnetic Resonance Imaging

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“…Subjects were stimulated with a Medtronic Magpro stimulator X100 (Skovlunde, Denmark), using a figure-of-eight coil, MC-B70 (for physical details see Thielscher and Kammer (2004)), fixed on a tripod. Double pulses with various SOAs were triggered by the PC with a precision of 100 ls using the digital output port of the graphics board VSG 2/3 (Cambridge Research Systems, Rochester, UK).…”

Section: Subjects and Apparatusmentioning

confidence: 99%

Phosphene thresholds evoked with single and double TMS pulses

Kammer

Baumann

2010

Clinical Neurophysiology

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“…(15) to (17). Where k r y k β are the radius and the angle for the kdipole respectively, whose values were reported in Table 1.…”

Section: Circular Coilmentioning

confidence: 99%

“…It has been shown that the electromagnetic field induced by a circular coil can be modeled by the superposition of the fields produced by several dipoles located at specific positions [17]. In particular, the approach firstly requires dividing the coil area into subregions, and subsequently locating a dipole in the center of each of them.…”

Section: Circular Coilmentioning

confidence: 99%

FDTD-based Transcranial Magnetic Stimulation model applied to specific neurodegenerative disorders

Fanjul-Vélez

Salas-García

Ortega-Quijano

et al. 2015

Computer Methods and Programs in Biomedicine

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Non-invasive treatment of neurodegenerative diseases is particularly challenging in Western countries, where the population age is increasing. In this work, magnetic propagation in human head is modeled by Finite-Difference Time-Domain (FDTD) method, taking into account specific characteristics of Transcranial Magnetic Stimulation (TMS) in neurodegenerative diseases. It uses a realistic high-resolution three-dimensional human head mesh. The numerical method is applied to the analysis of magnetic radiation distribution in the brain using two realistic magnetic source models: a circular coil and a figure-8 coil commonly employed in TMS. The complete model was applied to the study of magnetic stimulation in Alzheimer and Parkinson Diseases (AD, PD). The results show the electrical field distribution when magnetic stimulation is supplied to those brain areas of specific interest for each particular disease.Thereby the current approach entails a high potential for the establishment of the current underdeveloped TMS dosimetry in its emerging application to AD and PD.

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Electric field properties of two commercial figure-8 coils in TMS: calculation of focality and efficiency

Cited by 260 publications

References 22 publications

New coil positioning method for interleaved transcranial magnetic stimulation (TMS)/functional MRI (fMRI) and its validation in a motor cortex study

New coil positioning method for interleaved transcranial magnetic stimulation (TMS)/functional MRI (fMRI) and its validation in a motor cortex study

Phosphene thresholds evoked with single and double TMS pulses

FDTD-based Transcranial Magnetic Stimulation model applied to specific neurodegenerative disorders

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