Comparison between single- and dual-porosity models for fluid transport in predicting lesion volume following saline-infused radiofrequency ablation

Abstract

A recent study by Ooi and Ooi (EH Ooi, ET Ooi, Mass transport in biological tissues: Comparisons between single- and dual-porosity models in the context of saline-infused radiofrequency ablation, Applied Mathematical Modelling, 2017, 41, 271-284) has shown that single-porosity (SP) models for describing fluid transport in biological tissues significantly underestimate the fluid penetration depth when compared to dual-porosity (DP) models. This has raised some concerns on whether the SP model, when coupled with models of radiofrequency ablation (RFA) to simulate saline-infused RFA, could lead to an underestimation of the coagulation size. This paper compares the coagulation volumes obtained following saline-infused RFA predicted based on the SP and DP models for fluid transport. Results showed that the SP model predicted coagulation zones that are consistently 0.5 to 0.9 times smaller than that of DP model. This may be explained by the low permeability value of the tissue interstitial space, which causes the majority of the saline to flow through the vasculature. The absence of fluid flow tracking in the vasculature in the SP model meant that any flow of saline into the vasculature is treated as losses and do not contribute to the saline penetration depth of the tissue. Comparisons with experimental results from the literature revealed that the DP models predicted coagulation zone sizes that are closer to the experimental values than the SP models. This supports the hypothesis that the SP model is a poor choice for simulating the outcome of saline-infused RFA.

Thermal ablation of biological tissues in disease treatment: A review of computational models and future directions

“…Blood perfusion is one of the most critical parameters that significantly affect the accuracy of the computational model, especially with the Pennes bioheat transfer model that accounts for microvascular tissue perfusion in absence of the large blood vessels. In most of the computational studies on thermal ablation available in literature (Ewertowska et al, 2018a, Ewertowska et al, 2018b, Ooi et al, 2018, Qadri et al, 2017, Xu et al, 2019, a thermal damage-dependent piecewise model of blood perfusion is used, whereby complete cessation of the blood perfusion rate is assumed to occur at the threshold of different damage models due to the collapse of microvasculature within the tissue (Hall et al, 2015) and is given by ,0 if damage is below the threshold value 0 beyond the threshold value of damage…”

“…Most of the computational studies of thermal ablation available in the literature are based on coupled thermo-electric analysis (Barauskas et al, 2008, Ewertowska et al, 2018b, Ooi et al, 2018, Qadri et al, 2017, Singh and Repaka, 2017c, Zhang et al, 2015, Zorbas and Samaras, 2014, Zorbas and Samaras, 2015 and clearly neglects or underestimates the induced thermo-elastic deformations due to elevated temperature within the biological tissue. As mentioned earlier, the exposure of biological tissue to elevated temperatures during thermal ablative procedures can result in mechanical deformations, including both contractions and expansions.…”

“…Some researchers have adopted other boundary conditions, such as, the Robin type electrical boundary conditions to mimic the outflow of electric current to an infinite space and the thermal insulation condition to allow temperature at external boundary to increase in response to the heating induced during thermal ablation, etc. (Altrogge et al, 2007, Kröger et al, 2010, Ooi et al, 2018, Qadri et al, 2017. Recently, (Ooi et al, 2019) reported a computational study of RFA for treating liver cancer by considering geometrically-accurate models of the liver.…”