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Purpose <p>This study aimed to evaluate a novel multimodal thermal therapy (MTT)—defined here as sequential liquid nitrogen pre-freezing followed by radiofrequency ablation (RFA)—to overcome limitations of early lung tumor ablation by RFA—namely, high electrical impedance and heat sink effects, to achieve larger, more controllable ablation zones.</p> Methods <p>Using a porcine lung model (<i>n</i> = 3 pigs, 6 ablations/pig), multimodal ablation (pre-freezing + RFA) was compared to conventional RFA. Protocols included: 1) test group 1: 8-min pre-freezing + 40&#xa0;W/12-min RFA; 2) test group 2:&#xa0;15-min pre-freezing + 40&#xa0;W/15-min RFA; and 3) control group: 40&#xa0;W/12-min RFA alone. Ablation zones were assessed via CT and histology (H&amp;E). Real-time impedances and temperatures were monitored. A finite element model was developed to elucidate mechanisms.</p> Results <p>In comparison with the same power input of conventional RFA, pre-freezing created a conductive “parenchyma-like environment” via gas-to-blood displacement, reducing initial impedance by 52% (from 167.7 ± 48.1 to 80.8 ± 10.6 Ω). Paired analysis confirmed that MTT significantly decreased impedance and increased ablation dimensions and total energy delivery (all <i>p</i> &lt; 0.05). Parameters from the prediction model demonstrated spatial overlap between the pre-freezing 0&#xa0;°C isotherm and the RFA 60&#xa0;°C lethal boundary. Multimodal ablation increased the treatment zone minor diameter by 189% (25.7 ± 3.7 vs. 8.9 ± 1.6&#xa0;mm). A longer treatment period further increased the diameter to 30&#xa0;mm.</p> Conclusion <p>Pre-freezing is a promising strategy to enhance pulmonary RFA efficiency, significantly enlarging ablation zones via reduced impedance and improved conductivity, while conformal boundaries of 0&#xa0;°C/60&#xa0;°C enable precise intraoperative control. This work addressed a key limitation in lung tumor ablation. Enabling single-probe creation of predictable, clinically relevant zones could improve local control for early-stage lung tumors, potentiating minimal invasive thermal ablation in clinical practice.</p>

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A Multimodal Strategy for Enhancing Minimally Invasive Ablation of Lung Tumor

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年7月8日

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  • Rui Zhang,
  • Kangwei Zhang,
  • Yue Lou,
  • Guangzhi Wang,
  • Lisa X. Xu

摘要

Purpose

This study aimed to evaluate a novel multimodal thermal therapy (MTT)—defined here as sequential liquid nitrogen pre-freezing followed by radiofrequency ablation (RFA)—to overcome limitations of early lung tumor ablation by RFA—namely, high electrical impedance and heat sink effects, to achieve larger, more controllable ablation zones.

Methods

Using a porcine lung model (n = 3 pigs, 6 ablations/pig), multimodal ablation (pre-freezing + RFA) was compared to conventional RFA. Protocols included: 1) test group 1: 8-min pre-freezing + 40 W/12-min RFA; 2) test group 2: 15-min pre-freezing + 40 W/15-min RFA; and 3) control group: 40 W/12-min RFA alone. Ablation zones were assessed via CT and histology (H&E). Real-time impedances and temperatures were monitored. A finite element model was developed to elucidate mechanisms.

Results

In comparison with the same power input of conventional RFA, pre-freezing created a conductive “parenchyma-like environment” via gas-to-blood displacement, reducing initial impedance by 52% (from 167.7 ± 48.1 to 80.8 ± 10.6 Ω). Paired analysis confirmed that MTT significantly decreased impedance and increased ablation dimensions and total energy delivery (all p < 0.05). Parameters from the prediction model demonstrated spatial overlap between the pre-freezing 0 °C isotherm and the RFA 60 °C lethal boundary. Multimodal ablation increased the treatment zone minor diameter by 189% (25.7 ± 3.7 vs. 8.9 ± 1.6 mm). A longer treatment period further increased the diameter to 30 mm.

Conclusion

Pre-freezing is a promising strategy to enhance pulmonary RFA efficiency, significantly enlarging ablation zones via reduced impedance and improved conductivity, while conformal boundaries of 0 °C/60 °C enable precise intraoperative control. This work addressed a key limitation in lung tumor ablation. Enabling single-probe creation of predictable, clinically relevant zones could improve local control for early-stage lung tumors, potentiating minimal invasive thermal ablation in clinical practice.