Combination Therapies: Quantifying the Effects of Transarterial Embolization on Microwave Ablation Zones

To quantify the effect of transarterial embolization on microwave (MW) ablations in an in vivo porcine liver model.

Hepatic arteriography and cone-beam computed tomography (CT) scans were performed in 6 female domestic swine. Two lobes were embolized to an endpoint of substasis with 100-300-μm microspheres. MW ablations (65 W, 5 min) were created in embolized (n = 15) and nonembolized (n = 12) liver by using a 2.45-GHz system and single antenna. Cone-beam CT scans were obtained to monitor the ablations, document gas formation, and characterize arterial flow. Ablation zones were excised and sectioned. A mixed-effects model was used to compare ablation zone diameter, length, area, and circularity.

Combined transarterial embolization and MW ablation zones had significantly greater area (mean ± standard deviation, 11.8 cm² ± 2.5), length (4.8 cm ± 0.5), and diameter (3.1 cm ± 0.6) compared with MW only (7.1 cm² ± 1.9, 3.7 cm ± 0.6, and 2.4 cm ± 0.3, respectively; P = .0085, P = .0077, and P = .0267, respectively). Ablation zone circularity was similar between groups (P = .9291). The larger size of the combined ablation zones was predominantly the result of an increase in size of the peripheral noncharred zone of coagulation (1.3 cm ± 0.4 vs 0.8 cm ± 0.2; P = .0104). Cone-beam CT scans demonstrated greater gas formation during combined ablations (1.8 cm vs 1.1 cm, respectively). Mean maximum temperatures 1 cm from the MW antennas were 86.6°C and 68.7°C for the combined embolization/ablation and MW-only groups, respectively.

Combining transarterial embolization and MW ablation increased ablation zone diameter and area by approximately 27% and 66%, respectively, in an in vivo non-tumor-bearing porcine liver model. This is largely the result of an increase in the size of the peripheral ablation zone, which is most susceptible to local blood flow.