Fig. 3.

a-b MR images of the human brain acquired with the thermal MR 8-channel applicator at 7.0 T. A gradient echo technique is shown with a spatial resolution of (0.5 × 0.5 × 2.0) mm³. c MRTh maps of an RF heating experiment on a cylindrical phantom using the applicator to focus SAR in the center of the phantom and to acquire MR images to be used for the MRTh method. The pulsed power RF amplifier of the MR system was used at 300 MHz (¹H proton excitation frequency at 7.0 T) to induce a temperature difference of ~11 °C in the center of the phantom after 3 min of RF heating. d Demonstration of 2D hotspot steering feasibility of the given setup with RF phase modulation between the channels [20]. A temperature of >7 °C in the vicinity of the phantom could be reached for an RF heating duration of 2 min. e-f Thermal simulations in human voxel model “Ella” [27] in order to demonstrate the capabilities of the applicator to generate a hotspot in (e) the center of the brain and (f) the periphery applying the same phase setting as in (d)