Developing new treatments for brain disorders poses many challenges for focused ultrasound researchers. While the blood brain barrier is a key obstacle for those developing drug delivery therapies, the skull poses significant difficulties for researchers designing sound-based treatments.
In a Foundation-sponsored project, Thilo Hoelscher, M.D., a neurologist and professor of Neuroscience and Radiology at the University of California, San Diego, is developing a database that will help clinicians individualize the intensity of sound waves for different types of skulls.
“For decades, it was absolutely unthinkable that ultrasound could pass through the skull without defocusing or without distortion of the beam,” Hoelscher notes. “Today, we can use ultrasound like an x-ray beam and focus in the brain no matter what the skull characteristics are.”
But, a daunting challenge remains: determining how much acoustic energy is needed to penetrate skulls of different thicknesses, densities and other properties. “This project is studying the acoustic behavior of ultrasound inside the skull, to learn how we have to set up the ultrasound system — how we have to deal with different skull characteristics.”
Hoelscher and his team have conducted their first experiments and created the first data sets. Eventually, they expect to have imaging and sound field measurements for about 150 types of human skulls. These results will be made available through the Foundation’s Collaborative Research Network or another open source to the worldwide focused ultrasound community.
According the John Snell, Ph.D., Technical Director of the Foundation’s Brain Program, the sound map database could ultimately serve as the “gold standard” for assessing the accuracy of focused ultrasound simulation software. It may also accelerate development of new noninvasive brain treatments in several ways. These include:
- better understanding of the nature of the skull correction issues
- simpler clinical workflow
- new strategies for reaching intracranial targets that may be currently inaccessible
- improved planning/simulation systems
- insights for the development of the next generation of transcranial transducers for MR-guided focused ultrasound
Written by Ellen C., McKenna