Transarterial Radioembolization with Yttrium-90 Glass Microspheres: Distribution of Residual Activity and Flow...

To evaluate the microsphere flow dynamics and residual yttrium-90 (⁹⁰Y) activity during and after transarterial radioembolization with glass microspheres and to assess the distribution and predilection sites of residual activity in the administration devices.

In this laboratory investigation, after 18 consecutive clinical transarterial radioembolization and 4 ex vivo experimental procedures with ⁹⁰Y glass microspheres, the distribution of residual activity in the administration devices was assessed by activimeter and positron emission tomography (PET)/CT measurements. During ex vivo procedures, microsphere outflow from the administration device was assessed by dynamic scintigraphic measurements.

Mean residual activity was 3.4% ± 1.7 (range, 0.9%-8.8%). Calculations showed a negative correlation between relative residual activity and prescribed activity (r = -0.4258, P = .0486) and a positive correlation between absolute residual activity and prescribed activity (r = 0.5345, P = .0104). The main predilection site was the Luer-Lok microcatheter connector. Lower activities were detected in the dose vial. Flow measurements showed that more than 98% of the final injected activity was transferred to the patient with the first 20 mL of saline solution.

Residual activity in the standard administration device for glass microsphere radioembolization is considered to be low compared with similar procedures, but is variable. The microsphere flow profile shows an initial peak, resulting in a rapid activity transfer at the beginning of the injection process. The findings may have implications for safe handling of the administration device and for dose calculation of ⁹⁰Y glass microspheres.