Coded Excitation for Increased Sensitivity in Transcranial Power Doppler Imaging

Functional ultrasound imaging (fUSI) is a promising new modality for neuroimaging that measures the power Doppler signal as a proxy for neural activation. However, clinical translation of noninvasive, transcranial fUSI (tfUSI) is hindered by the low signal-to-noise ratio (SNR) from the skull which greatly limits blood flow sensitivity. To overcome this issue, we demonstrate a coded excitation approach to increase SNR in transcranial power Doppler imaging and thereby increase blood flow sensitivity. In three healthy adult subjects we showed an average SNR gain of 17.77
$\pm 1.05\ \mathbf{dB}$
, contrast-to-noise ratio gain of 4.97
$\pm 4.18\ \mathbf{dB}$
, and contrast ratio gain of
$22.53 \pm 11.34\ \text{dB}$
using a 65 bit code. These promising results indicate that tfUSI may be feasible using our coded excitation approach.