A simulation study on safety and efficacy of tFUS

Transcranial Focused Ultrasound Stimulation (tFUS) is a non-invasive technique for brain stimulation, which has a better spatial resolution and depth penetration with respect to other non-invasive techniques. Computational analysis could be a useful tool to predict tFUS propagation in biological tissue in order to guarantee safety and efficacy of the stimulation. This work aims at evaluating, by the means of a computational model, the maximum pressure and the average acoustic intensity generated by a pulsed tFUS stimulation waveform, whose duty cycle (DC) was modulated in the range from 100% to 40%. The main goal was to investigate the efficacy and the safety, respectively in terms of pressure and intensity, of the stimulus waveform when the DC is decreased. Moreover, the Full Width at Half Maximum (FWHM) intensity at the focus was observed. The obtained results showed that the amount of average acoustic intensity decreased with the DC and the maximum pressure remains constant. Therefore, low value of DC permits to effectively and safely extend the stimulation duration. Moreover, the FWHM did not vary during DC modulation; hence, the spatial resolution of the focus remained unchanged. These results suggest that tFUS can be adopted to safely stimulate the somatosensory cortex, properly modulating the stimulus duration, in order to elicit different sensations in the human hand.