A porous medium approach to thermal analysis of focused ultrasound for treatment of thyroid nodules

Abdolhosseinzadeh, Amir; Mojra, Afsaneh; Hooman, Kamel

doi:10.1016/j.apacoust.2021.108236

Cited by 3 publications

(3 citation statements)

References 48 publications

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“…In Equation (1), the first two statements show the Westervelt equation for linear behavior, the third statement shows the loss of thermal conductivity and fluid thermo‐viscous property, and the last term refers to nonlinear wave behavior with finite amplitude. To calculate the temperature, the following Pennes BHTE is used 25–27 :

\begin{equation}{\rho }_t{c}_t\frac{{\partial {T}_t}}{{\partial t}} = \ {k}_{t\ }{\nabla }^2{T}_t - \ {w}_b{c}_b\left( {T - {T}_b} \right) + \ Q\ \end{equation}

where indices t and b are tissue and blood parameters, respectively. w b and Q are the blood perfusion rate and external heat source, respectively.…”

Section: Methodsmentioning

confidence: 99%

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Numerical study of high‐intensity focused ultrasound (HIFU) in fat reduction

MORTAZAVI

Mokhtari‐Dizaji

2023

Skin Research and Technology

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Introduction:This study aimed to investigate the effect of fat-layer thickness and focal depth on the pressure and temperature distribution of tissue. Methods:Computer simulations were performed for the skin-fat layer models during high-intensity focused ultrasound (HIFU) treatment. The acoustic pressure field was calculated using the nonlinear Westervelt equation and coupled with the Pennes bioheat transfer equation to obtain the temperature distribution. To investigate the effect of the thickness of the fat layer on pressure and thermal distributions, the thickness of the fat layer behind the focal point (z = 13.5 mm) changed from 8 to 24 mm by 2 mm step. The pressure and temperature distribution spectra were extracted. Results:The simulated results were validated using the experimental results with a 98% correlation coefficient (p < 0.05). There was a significant difference between the pressure amplitude and temperature distribution for the 8-14 mm thickness of the fat layer (p < 0.05). By changing the focal point from 11.5 to 13.5 mm, the maximum acoustic pressure at the focal point increased 66%, and the maximum temperature was 56%, respectively. Conclusion:Considering the specific treatment plan for each patient, according to the skin and fat layer thicknesses, can help prevent side effects and optimize the treatment process of HIFU.

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\begin{equation}{\rho }_t{c}_t\frac{{\partial {T}_t}}{{\partial t}} = \ {k}_{t\ }{\nabla }^2{T}_t - \ {w}_b{c}_b\left( {T - {T}_b} \right) + \ Q\ \end{equation}

where indices t and b are tissue and blood parameters, respectively. w b and Q are the blood perfusion rate and external heat source, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…In Equation (1), the first two statements show the Westervelt equation for linear behavior, the third statement shows the loss of thermal conductivity and fluid thermo-viscous property, and the last term refers to nonlinear wave behavior with finite amplitude. To calculate the temperature, the following Pennes BHTE is used [25][26][27] :…”

Section: Physics Theorymentioning

confidence: 99%

Numerical study of high‐intensity focused ultrasound (HIFU) in fat reduction

MORTAZAVI

Mokhtari‐Dizaji

2023

Skin Research and Technology

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“…However, contrary to our study, their model focused on two treatment strategies related to the electrode system, i.e., singlecooled-electrode modality and two-cooled-electrode system. In addition, other studies considered the development of an FE model of the thyroid, but the simulations were focused on a different treatment method, e.g., focused ultrasound [29,30]. Other publications focused on the development of FE models of the neck region for the analysis of bioheat transfer in the human neck and subsequent comparison with images achieved with infrared thermography [25,31,32].…”

Section: Introductionmentioning

confidence: 99%

Model-Optimizing Radiofrequency Parameters of 3D Finite Element Analysis for Ablation of Benign Thyroid Nodules

Bini,

Pica,

Marinozzi

et al. 2023

Bioengineering

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Radiofrequency (RF) ablation represents an efficient strategy to reduce the volume of thyroid nodules. In this study, a finite element model was developed with the aim of optimizing RF parameters, e.g., input power and treatment duration, in order to achieve the target volume reduction rate (VRR) for a thyroid nodule. RF ablation is modelled as a coupled electro-thermal problem wherein the electric field is applied to induce tissue heating. The electric problem is solved with the Laplace equation, the temperature distribution is estimated with the Pennes bioheat equation, and the thermal damage is evaluated using the Arrhenius equation. The optimization model is applied to RF electrode with different active tip lengths in the interval from 5 mm to 40 mm at the 5 mm step. For each case, we also explored the influence of tumour blood perfusion rate on RF ablation outcomes. The model highlights that longer active tips are more efficient as they require lesser power and shorter treatment time to reach the target VRR. Moreover, this condition is characterized by a reduced transversal ablation zone. In addition, a higher blood perfusion increases the heat dispersion, requiring a different combination of RF power and time treatment to achieve the target VRR. The model may contribute to an improvement in patient-specific RF ablation treatment.

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