Fig 1.
Demonstration of the heat sink effect in hepatic microwave ablation, depending on flow and distance to simulated hepatic vessels.
Considerable changes in ablation zone morphology as reflected by minimum radius and lesion area can be observed in ablation procedures performed within 15mm of perfused vessels. Red cross = position of microwave antenna; blue circle = position of vessel; red arrow = minimal ablation zone radius; green arrow = maximum ablation zone radius; red dashed line = real ablation zone area; green line = idealized ablation zone area.
Fig 2.
Minimum radius (A) and lesion area (B) of the ablation zone depending on applicator—vessel distance and vessel perfusion.
In ablation procedures with vessels perfused with 700 ml/min located at 10 and 15mm distance, minimum radius of the resulting ablation zone was reduced by 61% and 19%, as compared to ablations with non-perfused vessels. Analogue, lesion area was reduced by 35% and 10%, respectively.
Table 1.
Ablation zone parameters dependent on applicator–vessel distance and vessel perfusion.
In addition, p-values for comparison of ablation zone parameters dependent on vessel flow are presented.
Fig 3.
Temperature profile in ex microwave ablation of porcine liver, dependent on vessel perfusion and vessel–applicator distance.
Maximum temperature during the ablation cycle decreased significantly with increasing distance between vessel and microwave antenna as well as with increasing vessel flow (p<0.05).