Finite element modeling and experimental investigation of infiltration of sodium chloride solution into nonviable liver tissue

Rimantas Barauskas, Antanas Gulbinas¹, Giedrius Barauskas²

Department of System Analysis, Kaunas University of Technology, ¹Institute for Biomedical Research, ²Department of Surgery, Kaunas University of Medicine, Lithuania

Key words: radiofrequency ablation; computational modeling; hydraulic conductivity; experimental research.

Summary. The aim of this study was to establish a mathematical model of the infiltration of sodium chloride solution into cadaveric liver tissue.

Methods. The time law of the flow of the infiltrated fluid at every node of the finite element model was obtained in terms of Darcy’s velocity, pressure, and volumetric saturation fraction. The model equations interpret the liver tissue as a porous medium taking into account the hydraulic conductivity, capacity, and absorption mechanisms. Capability of the cadaveric liver tissue to absorb the fluid is taken into account by means of the nonlinear relationship of hydraulic capacity and absorption coefficients against the volumetric saturation fraction. To explain certain inadequacies between the computational model and experiment, the idealized models of empty blood vessels in the vicinity of the injection probe have been used. The model has been implemented in computational environment COMSOL Multiphysics. Experimental procedures were performed to analyze fluid infiltration and to calculate volume of fluid, which might be injected into certain volume of nonviable liver tissue.

Results. The necessary physical constants of hydraulic conductivity, capacity, and absorption of liver tissue have been determined by comparing the simulation results against the experimental data. The congruence of the modeling results against the experiment may be regarded as satisfactory.

Conclusion. The established model analyses distribution of injected solution taking into account the hydraulic conductivity, capacity, and absorption mechanisms of liver tissue. The obtained results are of importance developing complex models of electro-thermal heating coupled with heat advection by means of infiltrated sodium chloride solution.

Correspondence to G. Barauskas, Department of Surgery, Kaunas University of Medicine, Eivenių 2, 50009 Kaunas, Lithuania. E-mail: giedrius.barauskas@gmail.com

Received 5 October 2006, accepted 17 April 2007