Influence of Skull Anisotropic Mechanical Properties in Low-Intensity Focused Ultrasound

2016 ◽  
Vol 24 (01) ◽  
pp. 1650003 ◽  
Author(s):  
Mohamed K. Metwally ◽  
Hee-Sok Han ◽  
Hyun Jae Jeon ◽  
Sang Beom Nam ◽  
Seung Moo Han ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Wave Propagation ◽  
Normal Stress ◽  
Brain Stimulation ◽  
Transverse Direction ◽  
Focused Ultrasound ◽  
Anisotropic Properties ◽  
Low Intensity ◽  
Anisotropic Mechanical Properties ◽  
The Brain

Low-intensity focused ultrasound (LIFU) is a new noninvasive brain stimulation technique where ultrasound is applied with low frequency and intensity to focus at a target region within the brain in order to exhibit or inhibit neuronal activity. In applying LIFU to the human brain, the skull is the main barrier due to its well-known high anisotropic mechanical properties which will affect the ultrasound focusing thereby affecting the neuromodulation or brain stimulation. This study aims at investigating the influence of the anisotropic mechanical properties of the skull on ultrasound propagation and focusing in LIFU. In this study, we used 2D finite element (FE) head models incorporating the isotropic and anisotropic properties of the skull. Three kinds of stresses were examined and shown within the skull: namely the normal stress in the direction of wave propagation ([Formula: see text]-stress), normal stress in the transverse direction to the wave propagation ([Formula: see text]-stress), and shear stress. Our analysis show that although most of the pressure that reaches to the brain is due to the longitudinal wave propagation through the skull, the stress in the transverse direction to the wave propagation direction ([Formula: see text]-stress) has the main influence on the pressure profile inside the brain. The results also show that the anisotropic properties of the skull broaden the focal size about 19% and 13% in the longitudinal and transverse directions, respectively more than the case of considering the isotropic properties in the realistic 2D FE head model. The results indicate the importance of considering the anisotropic properties of the skull in practicing LIFU to achieve accurate targeting within the brain.

scholarly journals Modulation of Cerebellar Cortical Plasticity Using Low-Intensity Focused Ultrasound for Poststroke Sensorimotor Function Recovery

2018 ◽  
Vol 32 (9) ◽  
pp. 777-787 ◽  
Author(s):  
Hongchae Baek ◽  
Ki Joo Pahk ◽  
Min-Ju Kim ◽  
Inchan Youn ◽  
Hyungmin Kim
Keyword(s):  
Brain Stimulation ◽  
Focused Ultrasound ◽  
Cortical Plasticity ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Brain Regions ◽  
Adaptive Plasticity ◽  
Alternative Pathways ◽  
Low Intensity

Background. Stroke affects widespread brain regions through interhemispheric connections by influencing bilateral motor activity. Several noninvasive brain stimulation techniques have proved their capacity to compensate the functional loss by manipulating the neural activity of alternative pathways. Over the past few decades, brain stimulation therapies have been tailored within the theoretical framework of modulation of cortical excitability to enhance adaptive plasticity after stroke. Objective. However, considering the vast difference between animal and human cerebral cortical structures, it is important to approach specific neuronal target starting from the higher order brain structure for human translation. The present study focuses on stimulating the lateral cerebellar nucleus (LCN), which sends major cerebellar output to extensive cortical regions. Methods. In this study, in vivo stroke mouse LCN was exposed to low-intensity focused ultrasound (LIFU). After the LIFU exposure, animals underwent 4 weeks of rehabilitative training. Results. During the cerebellar LIFU session, motor-evoked potentials (MEPs) were generated in both forelimbs accompanying excitatory sonication parameter. LCN stimulation group on day 1 after stroke significantly enhanced sensorimotor recovery compared with the group without stimulation. The recovery has maintained for a 4-week period in 2 behavior tests. Furthermore, we observed a significantly decreased level of brain edema and tissue swelling in the affected hemisphere 3 days after the stroke. Conclusions. This study provides the first evidence showing that LIFU-induced cerebellar modulation could be an important strategy for poststroke recovery. A longer follow-up study is, however, necessary in order to fully confirm the effects of LIFU on poststroke recovery.

scholarly journals EXTH-17. TREATMENT OF MALIGNANT GLIOMAS WITH DRUG-LOADED MICROBUBBLES: CONCEPTION OF A PROMISING FUTURE THERAPEUTIC STRATEGY

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi85-vi86
Author(s):  
Ellina Schulz ◽  
Viviane Mawamba ◽  
Volker Sturm ◽  
Ralf-Ingo Ernestus ◽  
Ulrich Schatzschneider ◽  
...  
Keyword(s):  
Real Time ◽  
Therapeutic Strategy ◽  
Focused Ultrasound ◽  
Malignant Gliomas ◽  
Side Chains ◽  
Low Intensity ◽  
Promising Strategy ◽  
Systemic Side Effects ◽  
The Brain ◽  
Targeted Release

Abstract The major obstacles for an effective chemotherapy of glioblastomas (GBM) are the blood-brain barrier (BBB) and serious systemic side effects of the cytotoxic drugs. A new promising strategy could be the delivery of the chemotherapeutics across the BBB to the tumor site encapsulated in microbubbles. The microbubbles will shield the drug from detrimental systemic effects. Low intensity focused ultrasound (LIFU) allows opening of the BBB and a targeted release of the drugs within the brain tumor. We synthesized microbubbles ≤ 2 µm in diameter by thin-film hydration of lipids, which could be disintegrated applying LIFU. The toxicity was tested on GBM cell lines and neither the intact bubbles nor the lipids alone showed any toxic effects. Additionally, these cells were treated with 6 platinum(II) and palladium(II) complexes conjugated to lipophilic side chains of different length (C1, C8, C10) for 72 h. Cell viability was evaluated with MTT assay and in real-time utilizing the impedance-based xCELLigence DP-System. EC50 values were calculated from both assays and all six drugs were highly effective. Especially the palladium(II) compound with the C1-chain had a very low EC50 value (< 10 µM), while the longer chains and the platinum(II) compounds were less effective (EC50 10 - 30 µM). The real time proliferation assay of the drugs revealed an early and concentration-dependent onset of the cytotoxic effect, about 30 h after application. The lipophilic side chains of the drugs should allow encapsulating them into the microbubbles to develop an effective drug-delivery system for the treatment of GBM.

scholarly journals The effect and mechanism of low intensity focused ultrasound in the treatment of Parkinson's disease

2021 ◽  
Author(s):  
Ling Long ◽  
yunxiao zhong ◽  
Xiaodong Cai ◽  
Jinchi Liao ◽  
Xu Liu ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Brain Stimulation ◽  
Focused Ultrasound ◽  
Motor Symptoms ◽  
Future Outlook ◽  
Non Invasive ◽  
Low Intensity ◽  
Current State ◽  
Stimulation Method

ABSTRACT Parkinson’s disease (PD) is a chronic, progressive, neurodegenerative disease. A new brain-stimulation method, low-intensity focused ultrasound (LIFUS), has been shown to improve PD-associated motor symptoms and permeabilize the blood-brain barrier. LIFUS is especially attractive due to its non-invasive nature and represents a treatment option that could be incorporated into the future treatment of neurodegenerative diseases, including PD. In this paper, we describe the current state and future outlook of LIFUS for the treatment of PD. We also focus on the stimulation principles that underly the effects of LIFUS during PD treatment. The safety and limitations of LIFUS are also discussed.

scholarly journals Low-Intensity Focused Ultrasound-Mediated Attenuation of Acute Seizure Activity Based on EEG Brain Functional Connectivity

2021 ◽  
Vol 11 (6) ◽  
pp. 711
Author(s):  
Minjian Zhang ◽  
Bo Li ◽  
Xiaodong Lv ◽  
Sican Liu ◽  
Yafei Liu ◽  
...  
Keyword(s):  
Focused Ultrasound ◽  
Low Frequency ◽  
Brain Regions ◽  
Brain Network ◽  
Clustering Coefficient ◽  
Connection Strength ◽  
Functional Brain ◽  
Low Intensity ◽  
Functional Brain Network ◽  
The Brain

(1) Background: Ultrasound has been used for noninvasive stimulation and is a promising technique for treating neurological diseases. Epilepsy is a common neurological disorder, that is attributed to uncontrollable abnormal neuronal hyperexcitability. Abnormal synchronized activities can be observed across multiple brain regions during a seizure. (2) Methods: we used low-intensity focused ultrasound (LIFU) to sonicate the brains of epileptic rats, analyzed the EEG functional brain network to explore the effect of LIFU on the epileptic brain network, and continued to explore the mechanism of ultrasound neuromodulation. LIFU was used in the hippocampus of epileptic rats in which a seizure was induced by kainic acid. (3) Results: By comparing the brain network characteristics before and after sonication, we found that LIFU significantly impacted the functional brain network, especially in the low-frequency band. The brain network connection strength across multiple brain regions significantly decreased after sonication compared to the connection strength in the control group. The brain network indicators (the path length, clustering coefficient, small-worldness, local efficiency and global efficiency) all changed significantly in the low-frequency. (4) Conclusions: These results revealed that LIFU could reduce the network connections of epilepsy circuits and change the structure of the brain network at the whole-brain level.

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