Non-Fourier Bioheat Transfer Analysis in Brain Tissue During Interstitial Laser Ablation: Analysis of Multiple Influential Factors

Abstract

This work presents the dual-phase lag-based non-Fourier bioheat transfer model of brain tissue subjected to interstitial laser ablation. The finite element method has been utilized to predict the brain tissue's temperature distributions and ablation volumes. A sensitivity analysis has been conducted to quantify the effect of variations in the input laser power, treatment time, laser fiber diameter, laser wavelength, and non-Fourier phase lags. Notably, in this work, the temperature-dependent thermal properties of brain tissue have been considered. The developed model has been validated by comparing the temperature obtained from the numerical and ex vivo brain tissue during interstitial laser ablation. The ex vivo brain model has been further extended to in vivo settings by incorporating the blood perfusion effects. The results of the systematic analysis highlight the importance of considering temperature-dependent thermal properties of the brain tissue, non-Fourier behavior, and microvascular perfusion effects in the computational models for accurate predictions of the treatment outcomes during interstitial laser ablation, thereby minimizing the damage to surrounding healthy tissue. The developed model and parametric analysis reported in this study would assist in a more accurate and precise prediction of the temperature distribution, thus allowing to optimize the thermal dosage during laser therapy in the brain.

Keywords: Bioheat transfer; Brain; Laser ablation; Mathematical modeling; Non-Fourier heat transfer; Thermal therapy.

Fig. 1

a Representation of interstitial laser ablation in the brain whereby an optical fiber, attached to the laser light system, is passed through a burr hole to the desired depth using image-guided modalities, and the laser light is interstitially delivered to heat the tissue (adapted from [4] under the terms of the Creative Commons CC BY License for an open access article). b Schematic of the axisymmetric model of the brain tissue derived from the selected cylindrical control volume, also highlighting the location of the fiber Bragg grating (FBG) sensor

Fig. 2

a Schematic of the experimental setup of interstitial laser ablation, b close-up of the positioning of laser applicator and fiber Bragg grating (FBG) sensor, and c photo of the calf brain tissue placed in the plexiglass box having holes at a desired location to maintain the positioning of laser fiber and FBG sensor

Fig. 3

Temperature profile recorded by the FBG array (chain of 10 FBG sensors) placed at a distance of 4 mm parallel from the laser applicator during the interstitial laser ablation of the calf brain tissue

Fig. 4

a Temperature profile at a point located at 4 mm radially away from the center of the laser fiber tip. b Ablation volume obtained by considering constant and variable (temperature-dependent) thermal properties during the interstitial laser ablation of ex vivo brain tissue

Fig. 5

Effect of variation in the magnitude of a τ_q, and b τ_t on the temperature profile monitored at a location of 4 mm radially away from the center of the laser fiber tip in comparison to the Pennes bioheat transfer model predictions

Fig. 6

Comparison between the experimentally measured and numerically predicted values of temperature variation with time during interstitial laser ablation of ex vivo calf brain tissue. Here, the black curve represents the mean value of the temperature of experimental findings, and the cyan color represents the standard deviation obtained after five experimental trials

Fig. 7

a Temperature profile predicted at a location of 4 mm radially away from the center of the laser fiber tip. b Ablation volume under non-perfused (i.e., without microvascular perfusion) and perfused (i.e. considering microvascular perfusion) settings of brain tissue during laser ablation

Fig. 8

Effect of input laser power on a the temperature profile predicted at a location of 4 mm radially away from the center of the laser fiber tip, and b the ablation volume during interstitial laser ablation

Fig. 9

Schematic of the ablation volume shapes attained after 300 s of interstitial laser ablation in brain tissue with a 2 W, b 4 W, and c 6 W of input laser power

Fig. 10

Effect of laser fiber applicator diameter on a the temperature profile predicted at a location of 4 mm radially away from the center of the laser fiber tip, and b the ablation volume during interstitial laser ablation

Fig. 11

Effect of laser wavelength on a the temperature profile predicted at a location of 4 mm radially away from the center of the laser fiber tip, b the ablation volume, and c the irradiation profile