Normalized Cross-Correlation Filtering for Transcranial Power Doppler Ultrasound in Adult Humans

Functional ultrasound has previously been demonstrated in small animal models and in adult humans without the skull. More recently, transcranial functional ultrasound in adults was demonstrated in central regions of the brain where larger, higher-velocity vessels are clustered. This was enabled in part because of coded transmit waveforms that boost SNR. Here, we demonstrate that functional assessment of more peripheral regions of the brain are possible with better clutter filtering that better isolates slow flow in high clutter and noise environments. To accomplish this, we utilize an adaptive normalized cross-correlation singular value selection technique to increase the effective field-of-view to include both the mid-brain and peripheral regions. We show correlation between the functional ultrasound signal and concurrently-acquired oxygen saturation data (0.744 ± 0.0423) to confirm functional response.