Acoustic properties across the human skull

Riis, Thomas; Webb, Taylor D.; Kubanek, Jan

doi:10.1016/j.ultras.2021.106591

Cited by 43 publications

(25 citation statements)

References 71 publications

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“…RTT is limited to transducer geometries and sections of the skull for which a through-transmit path can be established. We chose to place transducers parallel over the left and right sides of the skull as 1) there is a through-transmit path with minimal incidence angle to the skull 2) the parietal bone has favorable acoustic properties 19 , and 3) this geometry provides convenient coupling. Deviations from this geometry may incur loss of performance or practicality.…”

Section: Discussionmentioning

confidence: 99%

Controlled delivery of ultrasound through the head for effective and safe therapies of the brain

Riis

Wilson

Kubanek

2022

Preprint

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Transcranial focused ultrasound provides noninvasive and reversible approaches for precise and personalized manipulations of brain circuits, with the potential to transform our understanding of brain function and treatments of brain dysfunction. However, the effectiveness and safety of these approaches have been limited by the human head, which attenuates and distorts ultrasound strongly and unpredictably. To address this lingering barrier, we have developed a Relative Through-Transmit (RTT) approach that directly measures and compensates for the attenuation and distortion of a given skull and scalp. We have implemented RTT in hardware and demonstrated that it accurately restores the operator's intended intensities inside ex-vivo human skulls. Moreover, this functionality enabled effective and intensity-dependent transcranial modulation of nerves and effective release of defined doses of propofol inside the skull. RTT was essential for these new applications of transcranial ultrasound; when not applied, there were no significant differences from sham conditions. Moreover, RTT was safely applied in humans and accounted for all intervening obstacles including hair and ultrasound coupling. This method and hardware unlock the potential of ultrasound-based approaches to provide effective, safe, and reproducible precision therapies of the brain.

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Section: Discussionmentioning

confidence: 99%

Controlled delivery of ultrasound through the head for effective and safe therapies of the brain

Riis

Wilson

Kubanek

2022

Preprint

Self Cite

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“…Perhaps the first factor responsible for this variability is the type of transducer utilized to generate the ultrasonic waves ( 28 ). The second set of parameters is the skull’s impedance to LIFU penetration ( 28 , 48 , 49 ). As the thickness of animal models is not similar to human beings, it is difficult to reproduce the same preclinical effects in the clinic ( 50 ).…”

Section: Low-intensity Focused Ultrasoundmentioning

confidence: 99%

Low-Intensity Focused Ultrasound Technique in Glioblastoma Multiforme Treatment

et al. 2022

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Glioblastoma is one of the central nervous system most aggressive and lethal cancers with poor overall survival rate. Systemic treatment of glioblastoma remains the most challenging aspect due to the low permeability of the blood-brain barrier (BBB) and blood-tumor barrier (BTB), limiting therapeutics extravasation mainly in the core tumor as well as in its surrounding invading areas. It is now possible to overcome these barriers by using low-intensity focused ultrasound (LIFU) together with intravenously administered oscillating microbubbles (MBs). LIFU is a non-invasive technique using converging ultrasound waves which can alter the permeability of BBB/BTB to drug delivery in a specific brain/tumor region. This emerging technique has proven to be both safe and repeatable without causing injury to the brain parenchyma including neurons and other structures. Furthermore, LIFU is also approved by the FDA to treat essential tremors and Parkinson’s disease. It is currently under clinical trial in patients suffering from glioblastoma as a drug delivery strategy and liquid biopsy for glioblastoma biomarkers. The use of LIFU+MBs is a step-up in the world of drug delivery, where onco-therapeutics of different molecular sizes and weights can be delivered directly into the brain/tumor parenchyma. Initially, several potent drugs targeting glioblastoma were limited to cross the BBB/BTB; however, using LIFU+MBs, diverse therapeutics showed significantly higher uptake, improved tumor control, and overall survival among different species. Here, we highlight the therapeutic approach of LIFU+MBs mediated drug-delivery in the treatment of glioblastoma.

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“…Computational skull modeling, derived from each subject’s head CT or brain MRI, is a complex process which is currently being developed and validated with ongoing studies. 40 - 42 Further study in this area will also allow for use of LIFUS in a (paradoxically) less focused manner, to perhaps treat a broader area of cortex known to be epileptogenic, such as in some frontal lobe and other epilepsies.…”

Section: Current Challenges and Future Directionsmentioning

confidence: 99%

Low Intensity Focused Ultrasound for Epilepsy— A New Approach to Neuromodulation

2022

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Patients with drug-resistant epilepsy (DRE) who are not surgical candidates have unacceptably few treatment options. Benefits of implanted electrostimulatory devices are still largely palliative, and many patients are not eligible to receive them. A new form of neuromodulation, low intensity focused ultrasound (LIFUS), is rapidly emerging, and has many potential intracranial applications. LIFUS can noninvasively target tissue with a spatial distribution of highly focused acoustic energy that ensures a therapeutic effect only at the geometric focus of the transducer. A growing literature over the past several decades supports the safety of LIFUS and its ability to noninvasively modulate neural tissue in animals and humans by positioning the beam over various brain regions to target motor, sensory, and visual cortices as well as frontal eye fields and even hippocampus. Several preclinical studies have demonstrated the ability of LIFUS to suppress seizures in epilepsy animal models without damaging tissue. Resection after sonication to the antero-mesial lobe showed no pathologic changes in epilepsy patients, and this is currently being trialed in serial treatments to the hippocampus in DRE. Low intensity focused ultrasound is a promising, novel, incisionless, and radiation-free alternative form of neuromodulation being investigated for epilepsy. If proven safe and effective, it could be used to target lateral cortex as well as deep structures without causing damage, and is being studied extensively to treat a wide variety of neurologic and psychiatric disorders including epilepsy.

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Acoustic properties across the human skull

Cited by 43 publications

References 71 publications

Controlled delivery of ultrasound through the head for effective and safe therapies of the brain

Controlled delivery of ultrasound through the head for effective and safe therapies of the brain

Low-Intensity Focused Ultrasound Technique in Glioblastoma Multiforme Treatment

Low Intensity Focused Ultrasound for Epilepsy— A New Approach to Neuromodulation

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