Therapeutic effects of low-intensity transcranial focused ultrasound stimulation on ischemic stroke in rats: an in vivo evaluation using electrical impedance tomography

Although previous studies have demonstrated that transcranial focused ultrasound stimulation protects the ischemic brain, clear criteria for the stimulation time window and intensity are lacking. Electrical impedance tomography enables real-time monitoring of changes in cerebral blood perfusion within the ischemic brain, but investigating the feasibility of using this method to assess post-stroke rehabilitation in vivo remains critical. In this study, ischemic stroke was induced in rats through middle cerebral artery occlusion surgery. Transcranial focused ultrasound stimulation was used to treat the rat model of ischemia, and electrical impedance tomography was used to measure impedance during both the acute stage of ischemia and the rehabilitation stage following the stimulation. Electrical impedance tomography results indicated that cerebral impedance increased after the onset of ischemia and decreased following transcranial focused ultrasound stimulation. Furthermore, the stimulation promoted motor function recovery, reduced cerebral infarction volume in the rat model of ischemic stroke, and induced the expression of brain-derived neurotrophic factor in the ischemic brain. Our results also revealed a significant correlation between the impedance of the ischemic brain post-intervention and improvements in behavioral scores and infarct volume. This study shows that daily administration of transcranial focused ultrasound stimulation for 20 minutes to the ischemic hemisphere 24 hours after cerebral ischemia enhanced motor recovery in a rat model of ischemia. Additionally, our findings indicate that electrical impedance tomography can serve as a valuable tool for quantitatively evaluating rehabilitation after ischemic stroke in vivo. These findings suggest the feasibility of using impedance data collected via electrical impedance tomography to clinically assess the effects of rehabilitatory interventions for patients with ischemic stroke.