Flushing effect of micro-bolus pulse injection and its potential impact on peripheral veins under hemostasis

To explore the feasibility of using micro-bolus pulse injection method to reduce the dilution effect of pipeline on high concentration injection, and to understand low liquid volume bolus injection based on low injection speed. Using a programmable pulse injection pump, a 25-cm – long pipeline containing water-soluble fluorescent agent was flushed using different volumes of bolus, and the time spent for the complete disappearance of the fluorescent agent was recorded to evaluate the flushing efficiency. The finite element simulation of 2-phase flow was carried out using computational fluid dynamics (CFD) technology, and the difference of shear rate and pressure distribution in the vein of pulse injection and direct injection of bolus under hemostasis was compared and simulated. Micro-bolus pulse flushing has advantages in completing perfusion imaging applications, such as small volume imaging agent injection. Compared with non-pulse injection, the effective flushing volume decreases by 49.7%, the average injection speed decreases by 56%, and the maintenance time of high shear rate is shorter when using micro-bolus pulse injection. The impact of micro-bolus pulse injection on the vein can achieve the same or even lower negative effects as other injection methods after increasing the hemostatic distance to 100 mm. In the case of bolus injection requiring high concentration and small volume, such as for radiopharmaceutical dynamic imaging, the application of micro-bolus pulse injection is an effective way to overcome the dilution phenomenon of the imaging agent in the pipeline. During hemostasis, the micro-bolus pulse injection needs to control a longer hemostasis distance to reduce the potential impact on peripheral veins.