Tess J Snoeijink, Anne van den Brekel, Jan L van der Hoek, Jaap G M Greve, H Remco Liefers, Milou Boswinkel, Simon J S Ruiter, Joey Roosen, Erik Groot Jebbink, J Frank W Nijsen
Background: Transarterial radioembolisation (TARE) is a treatment for liver malignancies, involving the injection of radioactive microspheres in the hepatic artery (HA). Tumour-to-nontumour uptake varies among patients, possibly influenced by patient-specific blood flow profiles. To examine the impact of HA blood flow rate and high microsphere dosages on microsphere distribution in normal liver parenchyma, ex vivo magnetic resonance imaging (MRI)-guided machine perfusion experiments were conducted in porcine livers.
Materials and methods: Porcine livers were subjected to oxygenated normothermic machine perfusion at three HA flow rates (0.02, 0.15, and 0.22 mL/min/g liver tissue; n = 3 per condition). Five fractions of 250 mg nonradioactive 165Ho-loaded microspheres were administered to n = 9 livers, and four additional fractions of 1,000 mg to n = 6 livers. Dynamic contrast-enhanced and Ho-sensitive T2*-weighed MR scans were acquired to extract perfusion rates, fictive dose maps, and homogeneity indices (HI).
Results: Microsphere distribution correlated moderately with perfusion rate at low HA flow rate (r = 0.611), and very strongly at higher HA flow rates (r = 0.977 and 0.951 for 0.15 and 0.22 mL/min/g, respectively). Homogeneity increased with increasing flow rates, with HIs ranging from 3.68-4.72 at low, to 2.01-2.66 at medium, and 1.60-2.36 at high HA flow rate. HI decreased with higher microsphere concentrations, though distribution patterns remained unchanged.
Conclusion: In our ex vivo model, higher HA flow rates resulted in more homogeneous microsphere distributions. The impact on tumourous tissue needs further investigation to determine whether pre-TARE HA blood flow measurements could improve microsphere distribution predictions.