A 15-Min Method for Hydrophone Spatial Averaging Correction in Transcranial Neuromodulation System Characterization

Area of Science:

• Neuroscience
• Biomedical Engineering
• Acoustics

Background:

• Transcranial ultrasonic stimulation (TUS) is a non-invasive neuromodulation technique.
• Accurate characterization of TUS systems is crucial for reproducible research and clinical applications.
• Hydrophone spatial averaging is a recognized potential source of error in acoustic measurements.

Purpose of the Study:

• To quantify the error introduced by hydrophone spatial averaging in TUS system characterization.
• To provide a practical method for researchers to correct these measurement errors.
• To emphasize the importance of accounting for spatial averaging in TUS system specifications.

Main Methods:

• Analysis of 74 TUS system specification sets from 60 peer-reviewed publications.
• Exclusion of studies using hydrophones larger than the International Transcranial Ultrasonic Stimulation Safety and Standards Consortium (ITRUSST) recommended maximum.
• Computation of spatial averaging error correction factors for acoustic intensity.

Main Results:

• Hydrophone spatial averaging introduces significant errors in TUS system characterization.
• Correction factors for acoustic intensity were calculated: 1.10 ± 0.07 for human parameters, 1.12 ± 0.14 for animal parameters, and 1.18 ± 0.17 for high-frequency animal parameters.
• These findings confirm spatial averaging as a consistent source of error.

Conclusions:

• Hydrophone spatial averaging is a significant and common source of error in TUS system characterization.
• A straightforward method is presented for researchers to correct these errors using their TUS system specifications.
• Implementing this correction method enhances the reliability and accuracy of TUS research.