Reduced Apparent Diffusion Coefficient in Various Brain Areas following Low-Intensity Transcranial Ultrasound Stimulation

Abstract

Diffusion of water molecules closely related to physiological and pathological information of brain tissue. Low-intensity transcranial ultrasound stimulation (TUS) has advantages of noninvasive, high spatial resolution and penetration depth. Previous studies have demonstrate that TUS can modulate neuronal activity and alter cortical hemodynamic. However, how TUS affect diffusion of water molecules remain unclear. In this paper, in order to evaluate the effect of low-intensity TUS on the diffusion of water molecules in brain tissue, diffusion-weighted magnetic resonance (MR) imaging was performed in 19 healthy Sprague-Dawley rats in sham surgery group (six rats) and TUS group (thirteen rats) Subsequently, rats were stimulated by low-intensity transcranial ultrasound for 5 min in TUS group. Finally, rats of sham surgery group and TUS group were imaged again by diffusion-weighted MR imaging. The apparent diffusion coefficient (ADC) was measured in caudate putamen region and middle brain motor-related region of each rat in sham surgery group and TUS group. Surgery-related and TUS-related changes were calculated using a statistical analysis. The mean ADC values of marked regions of six rats in sham surgery group were 0.743 ± 0.031 (pre-surgery) and 0.745 ± 0.029 (post-surgery). The mean ADC values of marked regions of 13 rats in TUS group were 0.749 ± 0.032 (pre-TUS) and 0.712 ± 0.033 (post-TUS) Compared to the pre-TUS values, the mean ADC values of the rats decreased 4.9% (*P < 0.05) post-TUS. These results of this study demonstrate that low-intensity TUS can restrict the diffusion of water molecules in brain tissue.

Localized Modification of Water Molecule Transport After Focused Ultrasound-Induced Blood–Brain Barrier Disruption in Rat Brain

“…Earlier studies on ultrasound stimulation via DTI measures have shown a reduction in the ADC signal ( Schneider et al, 2006 ; Chu et al, 2014 ; Yuan et al, 2017 ). Yuan et al (2017) reported a restriction in water molecules by low-intensity transcranial ultrasound stimulation.…”

“…Earlier studies on ultrasound stimulation via DTI measures have shown a reduction in the ADC signal ( Schneider et al, 2006 ; Chu et al, 2014 ; Yuan et al, 2017 ). Yuan et al (2017) reported a restriction in water molecules by low-intensity transcranial ultrasound stimulation. Schneider et al (2006) reported a dose-dependent damaging effect and a significant decrease in the ADC and an increase in the T2 relaxation time by transcranial low-frequency 20 kHz ultrasound, which infers vasogenic and cytotoxic brain edema.…”

“…A decrease in ADC in sonication regions indicates relatively slower water diffusion arising from restrictions as compared to the water diffusion in the contralateral regions ( Sotak, 2004 ). An early report by Yuan et al (2017) showed a restriction in water molecules by low-intensity transcranial ultrasound stimulation and suggested that a decrease in ADC signal might be related to the swelling of astrocytes resulting from neuronal excitability caused by ultrasound stimulation. Chu et al (2014 , 2015) found a transient decrease in the ADC signal and suppressed neuromodulation accompanying FUS–BBBD.…”

Neuroprotective Effect of Low-Intensity Transcranial Ultrasound Stimulation in Moderate Traumatic Brain Injury Rats

“…Studies have demonstrated LITUS's regulatory effects on epilepsy, depression, anxiety, and other neurological disorders (Stuart et al, 2013;Panczykowski et al, 2014). Our previous study found that LITUS has a regulatory effect on the diffusion of brain water molecules, and this leads to a change in the apparent diffusion coefficient (ADC) value of brain tissue in the LITUS stimulation region (Yuan et al, 2017). Recent studies have shown that LITUS brain stimulation can awaken patients with severe post-TBI consciousness disorders, and patients can recover successfully under ultrasound stimulation (Monti et al, 2016).…”

Low-Intensity Pulsed Ultrasound Stimulation Modulates the Nonlinear Dynamics of Local Field Potentials in Temporal Lobe Epilepsy

“…Previous studies used LIPUS to stimulate different regions of the brain of rodent animals, monkeys, and humans. They found that LIPUS can modulate neuronal activity (Tyler et al, 2008; Tufail et al, 2010), neural network connections (Yu et al, 2016), cerebral hemodynamics (Yang et al, 2018; Yuan et al, 2018), and water molecular diffusion (Yuan et al, 2017). Previous studies have also shown that LIPUS can cause a reduction in the occurrence of epileptic EEG bursts and severity of epileptic behavior and can also result in fewer spontaneous recurrent seizures and improved performance in behavioral tasks assessing sociability and depression in the chronic period of epilepsy (Min et al, 2011; Hakimova et al, 2015).…”