Sensitivity of microwave ablation models to tissue biophysical properties: A first step toward probabilistic modeling and treatment planning

Šebek, Jan; Albin, Nathan; Bortel, Radoslav; Natarajan, Balasubramaniam; Prakash, Punit

doi:10.1118/1.4947482

Cited by 62 publications

(55 citation statements)

References 47 publications

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“…This premise is further supported by a recent computer modeling study, where MWA ablation zones varied only slightly when considering heterogeneity between tumor and normal tissue dielectric properties, compared to assuming homogeneous properties [9]. Additional studies have identified other heterogeneous tissue properties such as blood perfusion between tumor and normal tissue, to be a more relevant factor for accurate modeling of MWA than dielectric properties [9,38]. As such, the proposed approach affords inclusion of patient-specific blood perfusion in thermal models to address the growing interest in MWA treatment planning.…”

Section: Discussionmentioning

confidence: 90%

Experimental measurement of microwave ablation heating pattern and comparison to computer simulations

Deshazer

Prakash

Merck

et al. 2016

International Journal of Hyperthermia

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Introduction For computational models of microwave ablation (MWA), knowledge of the antenna design is necessary, but the proprietary design of clinical applicators is often unknown. We characterized the specific absorption rate (SAR) during MWA experimentally and compared to a multi-physics simulation. Methods An infrared (IR) camera was used to measure SAR during MWA within a split ex vivo liver model. Perseon Medical’s short-tip (ST) or long-tip (LT) MWA antenna were placed on top of a tissue sample (n=6), and microwave power (15W) was applied for 6 min, while intermittently interrupting power. Tissue surface temperature was recorded via IR camera (3.3 fps, 320×240 resolution). SAR was calculated intermittently based on temperature slope before and after power interruption. Temperature and SAR data were compared to simulation results. Results Experimentally measured SAR changed considerably once tissue temperatures exceeded 100 °C, contrary to simulation results. The ablation zone diameters were 1.28 cm and 1.30 ± 0.03 cm (transverse), and 2.10 cm and 2.66 ± −0.22 cm (axial), for simulation and experiment, respectively. The average difference in temperature between the simulation and experiment were 5.6 °C (ST) and 6.2 °C (LT). Dice coefficients for 1000 W/kg SAR iso-contour were 0.74 ± 0.01 (ST) and 0.77 (± 0.03) (LT), suggesting good agreement of SAR contours. Conclusion We experimentally demonstrated changes in SAR during MWA ablation, which were not present in simulation, suggesting inaccuracies in dielectric properties. The measured SAR may be used in simplified computer simulations to predict tissue temperature when the antenna geometry is unknown.

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Section: Discussionmentioning

confidence: 90%

Experimental measurement of microwave ablation heating pattern and comparison to computer simulations

Deshazer

Prakash

Merck

et al. 2016

International Journal of Hyperthermia

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“…These models use numerical techniques to solve the partial differential equations which govern electromagnetic propagation, power deposition, and bioheat transfer to estimate the treatment zone following a defined microwave exposure . Recently, there has been renewed interest in the development of modeling techniques for predictive planning of ablation treatments . Currently, planning for MWA is done with vendor specification diagrams that provide estimates of expected ablation treatment region size as derived from experimental measurements, often conducted in nonperfused animal tissue .…”

Section: Introductionmentioning

confidence: 99%

Computational modeling of 915 MHz microwave ablation: Comparative assessment of temperature‐dependent tissue dielectric models

Deshazer

Hagmann²,

Merck

et al. 2017

Medical Physics

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The inclusion of decreased electrical conductivity above 95 °C, implemented with model B as guided by our experimental measurements, may be a good approach for approximating the dynamic changes that occur during MWA at 915 MHz. Although a step toward more effectively modeling MWA at 915 MHz, further investigation of the transition in dielectric properties with temperature and tissue shrinkage, especially at high temperatures is needed for more accurate simulations.

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“…Although in this paper applications were focussed on hyperthermia, the software package is more widely applicable for electromagnetic and thermal simulations, for example in research on high field MRI, RF ablation, mobile phones or RF safety in general [100][101][102][103][104][105][106][107]. With the widespread use of MR investigations and the increasing field strength of MR scanners, safety aspects become very important and the risk of MR-induced hot-spots can be evaluated using simulations [106].…”

Section: Discussionmentioning

confidence: 99%

Planning, optimisation and evaluation of hyperthermia treatments

Kok

Kotte

Crezee

2017

International Journal of Hyperthermia

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Background: Hyperthermia treatment planning using dedicated simulations of power and temperature distributions is very useful to assist in hyperthermia applications. This paper describes an advanced treatment planning software package for a wide variety of applications. Methods: The in-house developed Cþþ software package Plan2Heat runs on a Linux operating system. Modules are available to perform electric field and temperature calculations for many heating techniques. The package also contains optimisation routines, post-treatment evaluation tools and a sophisticated thermal model enabling to account for 3D vasculature based on an angiogram or generated artificially using a vessel generation algorithm. The use of the software is illustrated by a simulation of a locoregional hyperthermia treatment for a pancreatic cancer patient and a spherical tumour model heated by interstitial hyperthermia, with detailed 3D vasculature included. Results: The module-based set-up makes the software flexible and easy to use. The first example demonstrates that treatment planning can help to focus the heating to the tumour. After optimisation, the simulated absorbed power in the tumour increased with 50%. The second example demonstrates the impact of accurately modelling discrete vasculature. Blood at body core temperature entering the heated volume causes relatively cold tracks in the heated volume, where the temperature remains below 40 C. Conclusions: A flexible software package for hyperthermia treatment planning has been developed, which can be very useful in many hyperthermia applications. The object-oriented structure of the source code allows relatively easy extension of the software package with additional tools when necessary for future applications.

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Sensitivity of microwave ablation models to tissue biophysical properties: A first step toward probabilistic modeling and treatment planning

Cited by 62 publications

References 47 publications

Experimental measurement of microwave ablation heating pattern and comparison to computer simulations

Experimental measurement of microwave ablation heating pattern and comparison to computer simulations

Computational modeling of 915 MHz microwave ablation: Comparative assessment of temperature‐dependent tissue dielectric models

Planning, optimisation and evaluation of hyperthermia treatments

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