Comprehensive optimization of interferometric diffusing wave spectroscopy (iDWS) and preliminary clinical study

Diffuse Correlation Spectroscopy (DCS) has revealed that light speckle fluctuations can noninvasively measure cerebral blood flow index (CBFi). While conventional DCS provides marginal brain sensitivity in adult humans, new techniques have recently emerged to improve diffuse light throughput for measuring CBFi. Here we further optimize one such approach, interferometric diffusing wave spectroscopy, with respect to independent channel count, camera duty cycle and gain, incident power, noise and artifact mitigation, and data processing. We build the system on a cart and define conditions for stable operation. We show pulsatile CBFi monitoring at 4-4.5 centimeter source-collector separation in adults with moderate pigmentation (Fitzpatrick 4). We also report preliminary clinical measurements in the Neuro Intensive Care Unit. These results push the boundaries of iDWS CBFi monitoring performance beyond previous reports.