Study of flow effects on temperature-controlled radiofrequency ablation using phantom experiments and forward...

Area of Science:

• Medical Physics
• Interventional Radiology
• Biomedical Engineering

Background:

• Hepatic radiofrequency ablation (RFA) is a common cancer treatment.
• Blood flow near the ablation zone introduces variability in treatment efficacy.
• The impact of blood flow on temperature-controlled RFA requires further investigation.

Purpose of the Study:

• To investigate the effects of large-scale blood flow on temperature-controlled RFA.
• To analyze the influence of vessel size and flow rate on ablation outcomes.
• To validate numerical simulations against experimental data.

Main Methods:

• Experiments using tissue-mimicking phantoms with integrated flow channels.
• Radiofrequency ablation performed with a monopolar needle electrode and temperature-controlled power delivery.
• Varying channel radii and saline flow rates to assess impact on ablation zone size, energy delivery, and lesion shape.
• Finite volume simulations to model experimental conditions and outcomes.

Main Results:

• Ablation area decreased with increasing flow rate for smaller vessels ($$ 2 mm), with minimal change in energy input.
• For larger vessels ($$ 2 mm and $$ 3 mm), energy input increased with flow rate; ablation area decreased or increased respectively, but remained reduced compared to no-flow conditions.
• Directional effects (lesion shrinking upstream, extension downstream) were observed only in the smallest channel.
• Simulations including flow effects reduced the mean absolute error in ablated area prediction from 0.23 to 0.12.

Conclusions:

• Temperature control partially compensated for heat sink effects in larger vessels by increasing energy delivery.
• The study provides a foundational understanding of blood flow dynamics in RFA and validates simulation models.
• Phantom experiments are suitable for RFA model validation and understanding complex thermal phenomena.