Metrology at CENTUS

Investigating the physics of transcranial ultrasound stimulation in partnership with Â鶹´«Ã½ Science Park
Transducer brain stimulation tool applied on a patient's head at the Brain Stimulation Lab, part of CENTUS
Our researchers are looking at the precise measurement and standardisation of acoustic parameters in transcranial ultrasound stimulation (TUS). This includes the pressure, intensity and focal accuracy that ensures safe, effective and reproducible neuromodulation through the skull. This work aims to support future TUS studies.
 

Controlled, effective and reproducible applications

The development and use of TUS is changing rapidly, along with its standards, protocols, hardware and software. Furthermore, most TUS devices that come to market do not have regulatory approval and compliance with safety measurements and standards, with clinical and research users having no training in ultrasound engineering.
It is not currently possible to directly check the intensity or focal position in situ for TUS, in a way that can be done through other therapeutics such as transcranial magnetic stimulation (TMS).
Our work in this area aims to help ensure consistency and replicability across studies by first allowing us to understand and accurately characterise the acoustic field produced by a TUS device. Secondly, we can use the information to correctly define the field in acoustic simulation and ensure consistency across the acoustic output of the TUS device over time.
Three considerations are needed:
  • measurement
  • simulation
  • routine equipment checks.

Associated publications

Klein-Flügge, M. C., Fouragnan, E. F., & Martin, E. (2024). . Brain Stimulation, 17(1), 32-34.
 

International Transcranial Ultrasonic Stimulation Safety and Standards (ITRUSST)

Dr Fouragnan is an active member of ITRUSST, an international consortium safety group that has established recommendations based on existing guidelines for diagnostic ultrasound from regulatory bodies such as the Food and Drug Administration (FDA), the British Medical Ultrasound Society (BMUS) and the American Institute of Ultrasound in Medicine (AIUM).
The consortium also provide consensus on expert guides, guidelines and standardisation for TUS to inform regulatory bodies.
Simulated focused ultrasound beam (red/blue) and location of magnetic resonance spectroscopy measurement (white square) overlaid on a structural magnetic resonance image (MRI)

Establishing an expert consensus on considerations for the biophysical safety of TUS

There are two main biophysical risks associated with the application of TUS – mechanical and thermal bioeffects – the same as with diagnostic ultrasound.
  • Mechanical bioeffects: the risk of acoustic cavitation, tissue damage.
  • Thermal bioeffects: potential tissue heating and thermal damage.
ITRUSST has established recommendations based on existing guidelines from regulatory bodies such as the Food and Drug Administration (FDA), the British Medical Ultrasound Society (BMUS) and the American Institute of Ultrasound in Medicine (AIUM).
They review existing regulatory guidelines for biomedical ultrasound and consider their relevance for TUS and present parameters and levels considered to be biophysically safe. This safety limit may be higher than previous stated levels but are considered safe for TUS.
ITRUSST graph for consensus on safety of transcranial ultrasound stimulation
Image: Table 1, Summary of the parameters and levels considered by ITRUSST to be safe.
Read the full paper:

Centre for Therapeutic Ultrasound

One of the most advanced and comprehensive transcranial ultrasound stimulation (TUS) research centres in the world, led by Professor Elsa Fouragnan – a leading authority on brain stimulation research in the UK and recognised internationally.
The only centre that is investigating TUS safety, biomechanics and undertaking clinical studies, our multidisciplinary approach combined with working across several research labs and patient facilities is truly unique.
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