Abstract No. 1 ▪ ABSTRACT OF THE YEAR Creation of a Novel Ex Vivo Human Liver Model for Microwave Ablation Investigation

We aim to develop a novel dual-perfused ex vivo model using explanted human research livers to investigate microwave ablation (MWA). Institutional review board exemption was granted to this project due to lack of human subject research and anonymity of donors to researchers. After research consent, human research livers were received from deceased organ donors using standard surgical and transplant preservation techniques. A fluoroscopic compatible ex vivo dual arterial and portal perfusion system was used to perfuse and oxygenate the organ. Digital subtraction angiography of the arterial, portal, and biliary system was performed before and after MWA. MWA was performed using a 2.45 GHz system (AngioDynamics Solero) at 140 Watts for 6 minutes followed by placement of a spinal needle to mark the trajectory of the probe. MWA zones were segmented along the MWA trajectory to obtain maximal short axis diameter (SAD) and long axis diameter (LAD) measurements. Ellipsoid volume and sphericity were then calculated. A total of 12 human livers were obtained with 7 explanted livers undergoing successful perfusion and MWA procedures (58.3%). Average cold ischemic time was 76.8 hours (SD 58.8 hours, range 23 to 144.5 hours, n = 7). Continuous bile production was observed in five perfused livers (71.4%), including the two cirrhotic livers. Average oxygen consumption was 11.4 + 8.3 mL/min. No bile production was noted in livers with > 60 hours cold ischemic time (n = 2). Perfused MWA resulted in significantly smaller MWA dimensions than nonperfused ablations with average gross specimen MWA comparisons as follows (21 perfused MWAs vs 13 nonperfused MWAs, two-tailed t-test): SAD, 3.1 ± 0.4 cm vs 4.1 ± 0.5 cm (p < 0.001); LAD, 4.7 ± 0.6 cm vs 6.2 ± 0.4 cm (p < 0.001); volume, 23.8 ± 8.0 mL vs 54.9 ± 13.9 mL (p < 0.001); sphericity, 0.45 ± 0.11 vs 0.45 ± 0.11 (p = 0.87). Additional analysis by tissue type was performed, demonstrating a statistically significant increase in perfused MWA zones for livers with steatosis compared with cirrhosis (15 perfused steatosis MWAs vs 6 perfused cirrhosis MWAs, two-tailed t-test): SAD, 3.0 ± 0.2 cm vs 3.4 ± 0.5 cm (p < 0.05); LAD, 4.5 ± 0.6 cm vs 5.1 ± 0.3 cm (p < 0.05); volume, 20.9 ± 4.3 mL vs 30.9 ± 10.8 mL (p < 0.01); sphericity, 0.45 ± 0.11 vs 0.45 ± 0.12 (p = 0.90). We report the creation of an ex vivo human liver model for MWA research with the ability to produce the heat sink effect and study different hepatic tissue types. Further investigations into the impact of hepatic tissue type on MWA may be useful in an ex vivo model.