Tess J Snoeijink, Jan L van der Hoek, Anne van den Brekel, Gerhard van Wolfswinkel, Marcel J R Janssen, Erik Groot Jebbink, J Frank W Nijsen
Purpose: This study aimed to experimentally investigate how injection technique affects the distribution of microspheres during transarterial radioembolization in a successively bifurcating in vitro model.
Methods and materials: A symmetrical phantom, bifurcating 3 times into 8 outlets, was incorporated into a flow circuit. A blood-mimicking fluid was pumped through the phantom using a physiological representative waveform. A microcatheter was placed into the lumen of the phantom, and holmium-165 microspheres were administered with a conventional administration device and a newly designed controlled administration device, containing a rotating syringe to keep the microspheres in suspension during administration. Two clinicians performed manual injections to establish clinically relevant injection rates. Then, different injection profiles were tested using syringe pumps: pulsed vs continuous injections (24 mL/min), and reduced continuous injection rates (10 and 5 mL/min). Microspheres were collected at each outlet and their distribution over the 8 outlets was analyzed.
Results: Continuous high injection rates led to more homogeneous radial distributions of microspheres over the right side of the phantom (outlet 5-8 received 16.5%-23.1% of the microspheres per outlet) compared with the clinically standard used pulsed injections (outlet 5-8 received 11.3%-40.1% of the microspheres per outlet). In contrast, reduced continuous injection rates led to more selective distributions (outlet 5-8 received 2.5%-68.8% of the microspheres at 10 mL/min and 1.0%-80.0% at 5 mL/min).
Conclusions: Injection technique strongly influences the distribution of microspheres. During high continuous injections, more mixing between microspheres and blood-mimicking fluid was observed. This led to more uniform radial microsphere distributions, creating a more predictive setting for transarterial radioembolization.