Laser interstitial thermotherapy of small breast fibroadenomas: Numerical simulations

Marqa, Mohamad Feras; Mordon, Serge; Betrouni, Nacim

doi:10.1002/lsm.22097

Cited by 18 publications

(4 citation statements)

References 39 publications

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“…The results presented here demonstrate the feasibility of creating 10-20 mm diameter spherical ablation zones using water-cooled monopole antennas, by appropriate selection of operating frequency, cooling water temperature, applied power level, and ablation duration. While we investigated MWA for selective adrenal ablation, we note that other minimally-invasive thermal therapy modalities such as RFA [47] and lasers [48], as well as non-thermal approaches such as irreversible electroporation [49], may also have potential for treatment of benign adrenal adenomas, if optimized to deliver small treatment zones and maximally spare normal adrenocortical cells.…”

Section: Discussionmentioning

confidence: 99%

Microwave antennas for thermal ablation of benign adrenal adenomas

Fallahi

Clausing

Shahzad

et al. 2019

Biomed. Phys. Eng. Express

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Microwave thermal ablation is under consideration as a minimally invasive modality to treat 10-20 mm benign adrenal adenomas, while preserving normally functioning adjacent adrenal tissue, and returning the gland to a normally functioning status that is under normal regulation. In contrast to applications for tumor ablation, where devices have been developed with the objective of maximizing the size of the ablation zone for treating large tumors, a challenge for adrenal ablation is to minimize thermal damage to non-targeted adrenal tissue and thereby preserve adrenal function. Here, we investigate methods for creating small spherical ablation zones of volumes in the range 0.5-4 cm 3 for the treatment of benign adrenal adenomas using water-loaded microwave monopole antennas operating at 2.45 GHz and 5.8 GHz. Coupled electromagnetic and bioheat transfer simulations and experiments in ex vivo tissue were employed to investigate the effect of frequency, applied power, ablation duration, and coolant temperature on the length and width of the ablation zone. Experimental results showed that small spherical ablation zones with diameters in the range of 7.4-17.6 mm can be obtained by adjusting the applied power and ablation duration. Multi-way ANOVA analysis of the experimentally-measured ablation zone dimensions demonstrated that frequency of operation and ablation duration are the primary parameters for controlling the ablation zone length and width, respectively. Additionally, it was demonstrated that the coolant temperature provides another effective parameter for controlling the ablation zone length without affecting the ablation zone width. Our study demonstrates the feasibility of creating small spherical microwave ablation zones suitable for targeting benign adrenal adenomas.

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Section: Discussionmentioning

confidence: 99%

Microwave antennas for thermal ablation of benign adrenal adenomas

Fallahi

Clausing

Shahzad

et al. 2019

Biomed. Phys. Eng. Express

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“…This work focuses on bio-heat transfer phenomena in biological tissue. The main applications of this work are in tumour detection or blood perfusion reconstruction [1,2,3,4,5,6,7], cryosurgery [8,9,10,11], hyperthermia [12,13,14,15], laser treatment [16,17,18], thermoregulation simulations [19,20,21,22], etc. We aim to simulate naturally occurring problems of heat transfer in order to evaluate the tissue response.…”

Section: Introductionmentioning

confidence: 99%

Subdomain BEM formulations for the solution of bio-heat problems in biological tissue with melanoma lesions

Iljaž

Wrobel

Hriberšek

et al. 2017

Engineering Analysis with Boundary Elements

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The main objective of the research presented in this paper is the development of efficient subdomain BEM solvers for the solution of steady-state and transient bio-heat problems in biological tissue, particularly involving melanoma of different sizes such as Clark II and IV. The short-term goal of the work is to investigate which of the numerical schemes implemented here produces the highest accuracy and efficiency, as a first step towards the long-term goal of solving inverse bio-heat problems for tumour diagnostics, i.e. the detection of tumour size and tumour parameters. The numerical results show that quadratic elements produce high accuracy with coarser meshes, and are thus more computationally efficient for this type of problem. It was also found that, for transient problems, a BEM formulation using the time-dependent fundamental solution of the diffusion equation was more efficient than the use of the fundamental solution of the Laplace equation with a finite difference time discretisation scheme, as much larger time steps could be used for the same accuracy. This work proposes that the subdomain BEM with quadratic elements and a time-dependent fundamental solution provides high accuracy and reduced computational time, and is thus indicated for the inverse analysis of bio-heat problems.

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“…The diffusion co-efficient of light, 'D' (mm), inside the tissue [112] can be defined by equation 2.3.…”

Section: Laser Ablation Of Fibroidsmentioning

confidence: 99%

Microwave Ablation for Uterine Fibroids

2019

CMR

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Uterine fibroids are the most common tumors of the uterus, with a ~70-80% lifetime prevalence in women of childbearing age. Uterus sparing procedures are of increasing interest for the treatment of fibroids to avoid surgical complications, preserve fertility, and reduce treatment costs.Image-guided microwave thermal ablation is under investigation as a minimally-invasive alternative to gold-standard hysterectomy, offering potential to provide symptom alleviation while preserving the patient's fertility. This dissertation presents studies towards the technical feasibility assessment of hysteroscopic transcervical microwave ablation (MWA) technology for treating uterine fibroids with the objective of achieving localized thermal destruction of fibroids while precluding thermal damage to adjacent healthy tissues.Computational models, a powerful tool for the design and evaluation of candidate ablation technologies, require accurate specification of tissue dielectric properties and how these properties vary as a function of temperature during an ablation procedure. The dielectric properties of uterine fibroids within the microwave frequency range have not been previously reported, thus stunting the development of accurate modeling tools. This study presents, for the first time, the dielectric properties within the microwave frequency range (500 MHz to 6 GHz) of human uterine fibroids excised following hysterectomy procedures, and their variation across temperatures ranging between 23-150 ºC. At room temperature (23 ºC), values of ɛr ranged between 44.5-57.5 units with a decreasing trend seen at higher frequencies and ơeff varied between 0.91-6.02 Sm -1 with an increasing trend at higher frequencies. At temperatures close to the water vaporization point, ɛr, drops considerably i.e. to 12-14% of its baseline values for all measured frequencies. The ơeff initially rises till 98 ºC and then falls to 11-13% of its baseline values at 125 ºC for frequencies ≤ 2.45 GHz. The ơeff follows a decreasing trend for frequencies > 2.45 GHz and drops to ~ 6 % of its room temperature values. Furthermore, parametric models of temperature and frequency dependent dielectric properties of uterine fibroids were presented, which can be readily used in computer simulations for accurate modeling of MWA.While MWA applicators are in clinical use for a variety of indications, existing antenna designs are not well suited to ablation of 1 -3 cm type 2 uterine fibroids. Currently 2.45 GHz applicators are used for the MWA of fibroid tissues; these antennas typically have longer active lengths (~7-15 mm) compared to the radius of type 2 fibroids. A higher frequency 5.8 GHz applicator, which was expected to reduce the antenna radiating length was investigated. A 5.8 GHz water-cooled MWA applicator, suitable for insertion into targeted fibroids via the instrument channel of a hysteroscope, was designed for the treatment of small fibroids (1-3 cm diameter) using electromagnetic-bioheat transfer simulations. The prominent features of this applicator are ap...

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Laser interstitial thermotherapy of small breast fibroadenomas: Numerical simulations

Abstract: In this study, a good correlation was established between simulation and ex vivo experiments of LITT for fibroadenoma breast cancer.

Cited by 18 publications

References 39 publications

Microwave antennas for thermal ablation of benign adrenal adenomas

Microwave antennas for thermal ablation of benign adrenal adenomas

Subdomain BEM formulations for the solution of bio-heat problems in biological tissue with melanoma lesions

Microwave Ablation for Uterine Fibroids

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