Table 1.
Geometrical details of the three modeled coils.
Table 2.
Coil current values used in simulation.
Fig 1.
On the left (Fig 1A) is shown the plot of the electric field of the coil, while on the right (Fig 1B) it is shown the resulting current profile. The DC approximation in red (shaded area) Fig 1B. Both subplots are idealized and given for 50% machine power.
Fig 2.
Experimental and virtual setup.
On top (Fig 2A) photo of physical phantom; holder; MR flex coils. Fig 2Aa, top right, the actual TMS figure-of-8 coil with capsules visible in red. On bottom (Fig 2B) is shown a visualization of the phantom T2, coil model BSM-811 as well as a single slice of MR phase accumulation measurements.
Fig 3.
Volumetric tetrahedral mesh of the human head (FEM) model.
On the left (Fig 3A) a mid-coronal slice with well conforming to anatomy boundaries for each tissue. On the right (Fig 3B) a closer view of 3A, the black sided rectangle in Fig 3A, where individual pyramidal shapes for each tetrahedron are easy to discern.
Fig 4.
The three coil models and the empirical results.
From top to bottom BSM-811, BSM-819 and BSM-879: Fig 4A the 3D models of the three coils under investigation. Fig 4B shows the Bz results, coming from MR measurements (all slices are the same). Fig 4C shows the Bz results, coming from computer simulations. Finally, Fig 4D gives the AD (absolute difference) metric for each coil model, between MR measurements (Fig 4B) and numeric calculations (Fig 4C). The slice views (Fig 4B, C and D) correspond to the 1mm thick slice depicted in Fig 2B.
Fig 5.
Plot of Bz field at distance 4cm away from the coil.
On top Fig 5A absolute value of the measured magnetic field in the MRI and the predicted values for all three coil models. On bottom Fig. 5B The value of BSM-811 used as a baseline; MRI measures, BSM-819 and BSM-879 prediction relative to the baseline.
Fig 6.
Total electric field results from FEM.
On the left an overview image of the coil, the cortical gray matter sheet, semi-transparent skin rendering. On the right a close-up view (zoom-in) of the area just under the coil (M1 moto-cortex gyrus). Fig 6A coil model BSM-811 orthogonal to the M1 gyrus. Fig 6B coil model BSM-819 orthogonal to the M1 gyrus. Fig 6C coil model BSM-811 parallel to the M1 gyrus. Fig 6D coil model BSM-819 parallel to the M1 gyrus.
Fig 7.
Results for the electric field(s) inside our ROI.