Transarterial radioembolization (TARE) is an established treatment method for non-resectable liver tumors where radioactive microspheres block local blood supply to tumors and deliver targeted radiation. However, accurate prediction of the microsphere biodistribution in the liver is challenging. Here, we propose to use ultrasound contrast microbubbles as precursors to the microspheres allowing for contrast-enhanced ultrasound (DCE-US) flow field measurements. Resulting trajectories then provide a prediction of the microsphere biodistribution. BR-14 microbubbles and non-radioactive Holmium-165 microspheres were injected into an in-vitro-arterial flow phantom representing the right branch of the hepatic artery bifurcation. The results showed a good correlation between microbubble and microsphere distributions. Subsequently, the procedure was adapted to more complex and biologically relevant ex-vivo perfused porcine livers. For each liver, the microbubble distribution within a target area was analyzed in real-time using pixel-wise time–intensity curves. The microsphere deposition was assessed by means of quantitative MRI R2* mapping. Analysis of the MRI scans shows that the deposition pattern corresponds well to that determined in real-time by DCE-US. Furthermore, the feedback provided by our approach enabled optimization of the catheter position during the procedure for optimal microsphere deposition in the target lobe.
Versluis et al. (Wed,) studied this question.