Defining Injectability of Transcatheter Embolic Materials via Work of Injection: Correlation with Viscosity-Rise Temperature and User-Centered Performance Metrics

The development of liquid embolic materials for interventional radiology requires careful evaluation of the injectability, a key performance indicator. This study introduces the concept of “work of injection” to define injectability based on the principles of affective engineering. An aqueous polysaccharide embolic system was used as the prototype liquid embolic material. The relationship between the work of injection and the viscosity-rise temperature (VRT) was investigated using both mechanical infusers at constant injection rates and hand injections in a porous vascular model. For the constant-rate injections, the work of injection showed a positive correlation with the VRT within the temperature range of 21–26 °C. For hand injections, a new definition of work of injection was proposed—one that is independent of the operator’s injection pattern. This redefined metric also correlated with the VRT, establishing the work of injection as a unique and quantifiable indicator of liquid embolic material injectability. Additional performance metrics, including the volume required to reach the cast-tip contact and post-embolization endurance, were assessed by the in vitro embolization tests. The findings suggest that the newly defined work of injection for hand injections is a fundamental parameter that ensures the usability of liquid embolic materials and can serve as a key indicator in their development guided by affective engineering principles.