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Updated: Jul 9, 2026
Thermal Ablation for the Treatment of Abdominal Tumors
Published on: March 7, 2011
A Multimodal Strategy for Enhancing Minimally Invasive Ablation of Lung Tumor
Rui Zhang1, Kangwei Zhang1, Yue Lou2
1School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
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.
