Experimental study on thermal field in the vicinity of arterial bifurcation in microwave ablation therapy

The aim of this study is to investigate the effects of an arterial bifurcation on the temperature distribution during microwave ablation in a muscle-equivalent phantom.Two experiments with water flow rates of 42.39 mL/min and 70.79 mL/min in the typical range of blood flows in the hepatic artery of the human body were implemented. Temperature measurements inside the phantom were performed in the plane of the arterial bifurcation, in each experiment the microwave antenna was placed at three different positions at 10, 15 and 20 mm from the vessel.The heating pattern was not symmetrical around the antenna with large temperature gradients near the blood vessel when the antenna was near to the vessel (10 mm): The higher the blood velocity, the smaller the heated area. The heating pattern was more circular and symmetrical, and the temperature contours with the two given flow rates nearly coincide when the antenna was far away from the blood vessel (20 mm). The temperatures near the recirculation zone in the daughter arteries immediately after the bifurcation hardly vary with blood velocity.These results indicate that the flow rate in the vessel and the distance between the vessel and the antenna can significantly affect the heating pattern during thermal ablation. The effect of blood flow on ablation is negligible if the distance between blood vessel and antenna exceeds 20 mm, and vessel occlusion can be avoided. The present results can be helpful in clinical microwave ablation surgical planning.