Conductive interstitial thermal therapy device for surgical margin ablation:<b><i>In vivo</i></b>verification of a theoretical model

Shafirstein, Gal; Novák, Petr; Moros, Eduardo G.; Siegel, Eric R.; Hennings, Leah; Kaufmann, Yihong; Ferguson, Scott; Myhill, Jeffrey; Swaney, Mark; Spring, Paul M.

doi:10.1080/02656730701591476

Cited by 20 publications

(27 citation statements)

References 79 publications

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“…Previous studies indicate a threshold of t 43 ≥ 240 min corresponds to coagulative necrosis in soft tissues, and is used as an indicator of treatment endpoint for in vivo simulations and clinical treatments. [53][54][55][56] Due to the sharp thermal dose gradients at the edge of the ablation zone, a conservative threshold of t 43 ≥ 600 min was used as an indicator of visible thermal coagulation for ex vivo experiments and simulations, similar to a previously validated model of catheter-based ultrasound ablation. 43 Tissue acoustic and thermal properties were dynamically adjusted during the course of ablations as a function of accrued thermal dose and tissue temperature exposure.…”

Section: Iid Bioacoustic-thermal Modelmentioning

confidence: 99%

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Multiple applicator hepatic ablation with interstitial ultrasound devices: Theoretical and experimental investigation

et al. 2012

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Purpose: To evaluate multiple applicator implant configurations of interstitial ultrasound devices for large volume ablation of liver tumors. Methods: A 3D bioacoustic-thermal model using the finite element method was implemented to assess multiple applicator implant configurations for thermal ablation with interstitial ultrasound energy. Interstitial applicators consist of linear arrays of up to four 10 mm-long tubular ultrasound transducers, each under separate and dynamic power control, enclosed within a water-cooled delivery catheter (2.4 mm OD). The authors considered parallel implants with two and three applicators (clustered configuration), spaced 2-3 cm apart, to simulate open surgical placement. In addition, the authors considered two applicator implants with applicators converging and diverging at angles of ∼20• , 30• , and 45• to simulate percutaneous placement. Heating experiments (10-15 min) were performed and compared against simulations employing the same experimental parameters. To estimate the performance of parallel, multiple applicator configurations in an in vivo setting, simulations were performed taking into account a range of blood perfusion levels (0, 5, 12, and 15 kg m −3 s −1 ) that may occur in tumors of varying vascularity. The impact of tailoring the power supplied to individual transducer elements along the length of applicators is explored for applicators inserted in non-parallel (converging and diverging) configurations. Thermal dose (t 43 > 240 min) and temperature thresholds (T > 52• C) were used to define the ablation zones, with dynamic changes to tissue acoustic and thermal properties incorporated within the model. Results: Experiments in ex vivo bovine liver yielded ablation zones ranging between 4.0-5.6 cm × 3.2-4.9 cm, in cross section. Ablation zone dimensions predicted by simulations with similar parameters to the experiments were in close agreement (within 5 mm). Simulations of in vivo heating showed that 15 min heating and interapplicator spacing less than 3 cm are required to obtain contiguous, complete ablation zones. The ability to create complete ablation zone profiles for nonparallel implants was illustrated by tailoring applied power levels along the length of applicators. Conclusions: Parallel implants consisting of three interstitial ultrasound applicators in a triangular configuration yield complete ablation zones measuring up to 6.2 cm × 5.7 cm after 15 min heating. At larger interapplicator spacing, the level of blood perfusion in the tumor may yield indentations along the periphery of the ablation zone. Tailoring applied power along the length of the applicator can accommodate for nonparallel implants, without compromising safety.

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Section: Iid Bioacoustic-thermal Modelmentioning

confidence: 99%

“…In these simulations, tissue specific heat capacity was modified to account for the substantial heat sink associated with tissue water vaporization. 54,64 This is achieved by incorporating the latent heat of water vaporization as shown in Eq. (5):…”

Section: Iid Bioacoustic-thermal Modelmentioning

confidence: 99%

Multiple applicator hepatic ablation with interstitial ultrasound devices: Theoretical and experimental investigation

et al. 2012

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“…Cryoablation was accomplished by circulating liquid nitrogen within the probe and heating was subsequently applied via the same probe by inserting a 100 micron laser fiber to heat the end of the probe, immediately after freezing. Thus, heat was transferred by conduction, which is a very efficient and predictable method to perform cryo or high temperature ablation, as we demonstrated in other work 11,12 . The range of temperatures and times that were used in this study are summarized in table 1 below.…”

Section: Thermal Ablation Proceduresmentioning

confidence: 70%

Dual thermal ablation modality of solid tumors in a mouse model

et al. 2011

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Purpose: Develop a new combination therapy consisting of cryoablation and conductive high-temperature ablation for enhanced thermal ablation of solid tumors. Methods:We have constructed an invasive probe that can be used for consecutive cryoablation and hightemperature ablation (C/HTA), with a single insertion. The C/HTA probe was tested, in Balb/c mice bearing solid 4T1 tumors, in comparison to cryoablation and high temperature ablation, only. Three days after ablation, the diameter of the ablated zone was evaluated with pathological examination.Results: The C/HTA device can be used to induce larger ablation zones, in comparison to high temperature or cryoablation alone, and at lower thermal doses and temperatures than either modality alone. Conclusions:The relatively high thermal conductivity of ice, in comparison to water and native tissue, enables rapid heating of the ice-ball that result in improved conductive high temperature ablation. The new dual thermal modality improves ablation outcomes at lower thermal doses in comparison to a single ablation modality.

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“…For thermal ablation, the threshold for coagulative necrosis is within the range 100 < t 43 < 1000 min [69]. Numerous in vivo studies have shown a threshold of t 43 ≥ 240 to be in good agreement with the extent of coagulative necrosis after thermal ablation [69, 77–79]. Typical values applied for safety thresholds to represent non-lethal exposure are T<43 °C, t 43 < 5 min [68].…”

Section: Introductionmentioning

confidence: 99%

Modelling of endoluminal and interstitial ultrasound hyperthermia and thermal ablation: Applications for device design, feedback control and treatment planning

Prakash

Salgaonkar

Diederich

2013

International Journal of Hyperthermia

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Endoluminal and catheter-based ultrasound applicators are currently under development and are in clinical use for minimally invasive hyperthermia and thermal ablation of various tissue targets. Computational models play a critical role in in device design and optimization, assessment of therapeutic feasibility and safety, devising treatment monitoring and feedback control strategies, and performing patient-specific treatment planning with this technology. The critical aspects of theoretical modeling, applied specifically to endoluminal and interstitial ultrasound thermotherapy, are reviewed. Principles and practical techniques for modeling acoustic energy deposition, bioheat transfer, thermal tissue damage, and dynamic changes in the physical and physiological state of tissue are reviewed. The integration of these models and applications of simulation techniques in identification of device design parameters, development of real time feedback-control platforms, assessing the quality and safety of treatment delivery strategies, and optimization of inverse treatment plans are presented.

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Conductive interstitial thermal therapy device for surgical margin ablation:In vivoverification of a theoretical model

Cited by 20 publications

References 79 publications

Multiple applicator hepatic ablation with interstitial ultrasound devices: Theoretical and experimental investigation

Multiple applicator hepatic ablation with interstitial ultrasound devices: Theoretical and experimental investigation

Dual thermal ablation modality of solid tumors in a mouse model

Modelling of endoluminal and interstitial ultrasound hyperthermia and thermal ablation: Applications for device design, feedback control and treatment planning

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