Determine the appropriate time-averaging window for spatial-peak time-average intensity (I_spta) in TUS

Determine, based on characteristic diffusion times relevant to transcranial ultrasound stimulation, the maximum continuous no-stimulation interval that should be included when computing the spatial-peak time-average intensity (I_spta) for transcranial ultrasound stimulation protocols, to remove ambiguity in standardised reporting of time-averaged intensity.

Background

Transcranial ultrasound stimulation protocols often use intermittent pulsing at multiple repetition levels, creating ambiguity about the time window over which spatial-peak time-average intensity (I_spta) should be computed. The authors note that selecting an appropriate averaging period should be informed by characteristic diffusion times relevant to TUS, but that this remains under investigation, preventing a firm recommendation.

Clarifying this averaging window is important for consistent, meaningful reporting and comparison across studies, since including long periods with no stimulation can yield non-informative intensity metrics.

References

Ultimately, the maximum continuous length of time where no TUS is administered included in the I_\mathrm{spta calculation should be determined based on knowledge of characteristic diffusion times relevant to TUS. However, this is still a topic of active research, thus a recommendation cannot yet be made.

— ITRUSST Consensus on Standardised Reporting for Transcranial Ultrasound Stimulation  (2402.10027 - Martin et al., 2024) in Section “Spatial-Peak Time-Average Intensities” (Sec. \ref{Sec:timeav})