Management of adreno-cortical adenomas using microwave ablation: study of the effects of the fat tissue

Bottiglieri, Anna; O’Halloran, Martin; Ruvio, Giuseppe; Farina, Laura

doi:10.1080/02656736.2022.2114611

Cited by 4 publications

(14 citation statements)

References 48 publications

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“…Figure 1 B shows a three-dimension model used to study the influence of the orientation of the MW applicator on the ablation profiles at 5.8 GHz. The dimensions of the model and the orientations of the MW applicator with respect to the cortex-fat interface are consistent with those reported in [ 9 ].…”

Section: Methodssupporting

confidence: 85%

“…Thus, a difference in the absorption of the electromagnetic power between fat and adrenal tissues can be observed. As already observed in [ 7 , 8 , 9 ], the difference in the absorbed electromagnetic power between the two tissues results in asymmetric ablation profiles delineated by the isothermal contour at 55 °C ( Figure 3 , Figure 4 and Figure 5 (second row)).…”

Section: Resultssupporting

confidence: 71%

“…The width of the fat layer was set equal to 15 mm. A previous study [ 9 ] showed comparable asymmetric ablation profiles for different widths of the fat layer (15, 10, and 5 mm). The width of the medulla and the inner layer of cortex represent a realistic margin between the two functional adrenal tissues [ 12 , 13 , 14 ].…”

Section: Methodsmentioning

confidence: 66%

“…The extent of the ablation zones achieved in each tissue and for each setting are reported in Table 3 . The influence of the higher values of effective conductivity both for adrenal gland (

= 4.2 S·m −1 ) and fat (

= 0.5 S·m −1 ) at 5.8 GHz as compared with the values at 2.45 GHz [ 9 ] (

= 1.6 S·m −1 ;

= 0.1 S·m −1 ) is visible. The higher contrast in effective conductivity (

−

= 3.7 S·m −1 ) at 5.8 GHz results in higher heating rate as compared with those achieved at 2.45 GHz [ 9 ], using the same power and time settings.…”

Section: Resultsmentioning

confidence: 99%

“…A ‘side firing’ approach has been proposed to direct energy more specifically into the tumor, which may overcome risks linked to the position of adrenal adenomas in proximity to kidney, large and medium blood vessels, or nerves [ 5 , 6 ]. Alternatively, a method that leverages differences in dielectric properties between the adrenal medulla and cortex to enhance heating of the tumor has been explored [ 7 , 8 , 9 ]. The fat layer surrounding the adrenal glands has been used to confine the electromagnetic field and create asymmetric ablation profiles with an omnidirectional antenna at 2.45 GHz.…”

Section: Introductionmentioning

confidence: 99%

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MWA Performed at 5.8 GHz through ‘Side Firing’ Approach: An Exploratory Study

Bottiglieri

Brace

O’Halloran

et al. 2022

Sensors

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Recent studies have shown that ablation techniques have the potential to eradicate adrenal adenomas while preserving the functionalities of the adrenal gland and the surrounding anatomical structures. This study explores a new microwave ablation (MWA) approach operating at 5.8 GHz and using anatomical and dielectric characteristics of the target tissue to create directional heating patterns. Numerical simulations are executed in planar and 3D adrenal models, considering two energy doses. The numerical study is refined accounting for the vaporization of the tissue water content. Ex vivo experimental evaluations on porcine adrenal models complete the study. The numerical and experimental results show that spherical ablation zones are able to cover the target for both energy doses considered. Nonetheless, most of the non-targeted tissues can be preserved from excessive heating when low energy level is used. Numerical models accounting for water vaporization are capable to foresee the experimental temperature values. This study shows that the proposed MWA directional approach operating at 5.8 GHz can be considered for creating effective and selective ablation zones.

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Section: Methodssupporting

confidence: 85%

Section: Resultssupporting

confidence: 71%

Section: Methodsmentioning

confidence: 66%

“…The extent of the ablation zones achieved in each tissue and for each setting are reported in Table 3 . The influence of the higher values of effective conductivity both for adrenal gland (

= 4.2 S·m −1 ) and fat (

= 0.5 S·m −1 ) at 5.8 GHz as compared with the values at 2.45 GHz [ 9 ] (

= 1.6 S·m −1 ;

= 0.1 S·m −1 ) is visible. The higher contrast in effective conductivity (

−

= 3.7 S·m −1 ) at 5.8 GHz results in higher heating rate as compared with those achieved at 2.45 GHz [ 9 ], using the same power and time settings.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

MWA Performed at 5.8 GHz through ‘Side Firing’ Approach: An Exploratory Study

Bottiglieri

Brace

O’Halloran

et al. 2022

Sensors

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Adrenal ablation as a treatment for hypertension: analyzing the dielectric properties of adrenal glands for microwave ablation technologies

Amin,

Cappiello,

Kraśny

et al. 2023

Int. J. Microw. Wireless Technol.

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Adrenal gland-induced hypertension, also known as secondary hypertension, is a medical condition caused by an underlying adrenal pathology, most typically adrenocortical adenomas. Current clinical practices involve pharmacotherapy or surgical resection to treat adrenal gland diseases that cause hypertension. However, due to the limitations of these treatment options, microwave ablation (MWA) has emerged as a promising minimally invasive alternative. An accurate understanding of the dielectric properties of adrenal glands would support the further development and optimization of MWA technology for treating adrenal tumors. Only a few studies have examined the dielectric properties of both human and animal adrenal glands, and the sample sizes of these studies have been relatively small. Therefore, further dielectric data of human and animal adrenal glands are warranted. This paper presents the ex vivo dielectric properties of the ovine adrenal glands (medulla and cortex) and summarizes the published literature on dielectric data of adrenal glands from porcine, bovine, ovine, and human samples in the microwave frequency range to analyze the consistency and reliability of the reported data. The dielectric properties of the ovine adrenal glands (N = 8) were measured using an open-ended coaxial probe measurement technique at frequencies ranging from 0.5 to 8.5 GHz. This study also investigated the temperature-dependent dielectric properties of the ovine adrenal medulla ranging from 37 to 64°C at frequencies ranging from 0.5 to 8.5 GHz. The dielectric properties of the ovine adrenal medulla measured in this study were found to be consistent with the literature. Moreover, the review suggests that variations exist in the dielectric properties of the adrenal medulla and cortex among species. The study also found that the dielectric properties of the adrenal medulla decrease with increasing temperature, similar to other tissues for which temperature-dependent dielectric data have been reported. This summary of dielectric data of adrenal glands and the temperature-dependent dielectric properties of the ovine adrenal medulla will accelerate the development of MWA technologies for hypertension treatment.

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