Department of Biomedical Engineering, College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, China.
Int J Hyperthermia. 2022;39(1):868-879. doi: 10.1080/02656736.2022.2075041.
The charring tissue formation in the ablated lesion during the microwave ablation (MWA) of tumors would induce various unwanted inflammatory responses. This paper aimed to deliver appropriate thermal dose for effective ablations while preventing tissue carbonization by optimizing the treatment protocol during MWA with the set combinations of temperature control and pulsed microwave energy delivery.
The thermal phase transition of porcine liver tissues were recorded by differential scanning calorimetry (DSC) to determine the temperature threshold during microwave output control. MWA was performed by an in-house built system with the ease of microwave output parameter adjustment and real-time temperature monitoring. The effects of continuous and pulsed microwave deliveries as well as various intermittent time-set of MWA were evaluated by measuring the dimensions of the coagulation zone and the carbonization zone.
The DSC scans demonstrated that the porcine liver tissues have been in a state of endothermic heat during the heating process, where the maximum absorbed heat occurred at the temperature of 105 °C ± 5 °C. The temperature control during MWA resulted in effective coagulative necrosis while preventing tissue carbonization, after setting 100 °C as the upper threshold temperature and 60 °C as the lower threshold. Both the numerical simulation and experiments have shown that, upon the optimization of the time-set parameters in the periodic intermittent pulsed microwave output, the tissue carbonization was significantly diminished.
This study developed a straight-forward anti-carbonization strategy in MWA by modulating the pulsing mode and intermittent time. The programmed protocols of intermittent pulsing MWA have demonstrated its potentials toward future expansion of MWA technology in clinical application.
在肿瘤微波消融（MWA）过程中，消融灶内的碳化组织会引发各种不良的炎症反应。本研究旨在通过优化治疗方案，结合温度控制和脉冲微波能量传递，为有效消融提供合适的热剂量，同时防止组织碳化。
采用差示扫描量热法（DSC）记录猪肝组织的热相变过程，以确定微波输出控制过程中的温度阈值。采用自行设计的系统进行 MWA，便于调整微波输出参数和实时监测温度。通过测量凝固区和碳化区的尺寸，评估连续和脉冲微波输送以及 MWA 不同间歇时间设置的效果。
DSC 扫描显示，猪肝组织在加热过程中处于吸热状态，最大吸热发生在 105°C±5°C 的温度下。将 100°C 设定为上限温度，60°C 设定为下限温度，对 MWA 过程中的温度进行控制，可实现有效的凝固性坏死，同时防止组织碳化。数值模拟和实验均表明，通过优化周期性间歇脉冲微波输出的时间参数，可以显著减少组织碳化。
本研究通过调节脉冲模式和间歇时间，在 MWA 中开发了一种简单有效的抗碳化策略。间歇性脉冲 MWA 的程控方案显示了其在临床应用中进一步扩展 MWA 技术的潜力。
