Time-resolved X-ray PIV measurements of hemodynamic information of real pulsatile blood flows

X-ray imaging technique has been used to visualize various bio-fluid flow phenomena as a nondestructive manner. To obtain hemodynamic information related with circulatory vascular diseases, a time-resolved X-ray PIV technique with high temporal resolution was developed. In this study, to embody actual pulsatile blood flows in a circular conduit without changes in hemorheological properties, a bypass loop is established by connecting a microtube between the jugular vein and femoral artery of a rat. Biocompatible CO$_{2}$ microbubbles are used as tracer particles. After mixing with whole blood, CO$_{2}$ microbubbles are injected into the bypass loop. Particle images of the pulsatile blood flows in the bypass loop are consecutively captured by the time-resolved X-ray PIV system. The velocity field information are obtained with varying flow rate and pulsataility. To verify the feasibility of the use of CO$_{2}$ microbubbles under \textit{in vivo} conditions, the effects of the surrounding-tissues are also investigated, because these effects are crucial for deteriorating the image contrast of CO$_{2}$ microbubbles. Therefore, the velocity information of blood flows in the abdominal aorta are obtained to demonstrate the visibility and usefulness of CO$_{2}$ microbubbles under \textit{ex vivo} conditions.