In Vivo Pulsatility and Resistivity Measurement of Rat Spinal Cord Using Ultrafast Doppler Imaging: A Preliminary Study

Pulse waves propagating along vasculature serve as indicators reflecting vital parameters such as heart rate and blood pressure. Pulse wave in spinal cord may not only signifies functional status of spinal cord but also indicates potential risks of diseases. Therefore, wide-field imaging of the spinal cord pulsatility propagation from main feeding arteries to arterioles is crucial for hemodynamics evaluation and corresponding disease treatment. Despite the inherent challenges in spinal cord blood flow imaging, ultrafast Doppler presents advantages in pulsatility measurement due to its high imaging resolution and sensitivity. Moreover, in comparison to conventional pulsed-wave Doppler ultrasound, which operates at local areas with limited field of view, ultrafast Doppler enables the simultaneous estimation of full Doppler spectra across all pixels within wide field-of-view images. In this study, ultrafast Doppler imaging was performed on a rat spinal cord for in vivo pulsatility and resistivity measurement. Key indicators were extracted including peak systolic velocity (PSV), end diastolic velocity (EDV), and mean flow velocity (MFV). Then, pulsatility index (PI) and resistivity index (RI) were quantified by computing the key indicators and were mapped over the entire vascular network.