Concentration and volume effects in thermochemical ablation in vivo: Results in a porcine model

Cressman, Erik N.K.; Geeslin, Matthew G.; Shenoi, Mithun M.; Hennings, Leah; Zhang, Yan; Iaizzo, Paul A.; Bischof, John C.

doi:10.3109/02656736.2011.644621

Cited by 22 publications

(15 citation statements)

References 38 publications

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“…1 However, for larger tumors >5 cm in diameter, studies have reported lower complete ablation rates, 24% and 62% in tumors measuring 5-9.5 cm and 5-7 cm. 8 Similar results have been reported with early MW ablations systems. Suggested reasons for recurrence due to inadequate ablation include limitations of the heat-sink effect associated with large blood vessels, imprecise placement of applicators during sequential ablations resulting in nonoverlapping ablation zones, limitations of the heating technology, and poor visualization of the treatment zone on preoperative and postoperative imaging.…”

Section: Introductionsupporting

confidence: 80%

“…Since ultrasound energy from interstitial applicators is tightly collimated to the individual transducers along the length of the applicator, 16 it offers the potential to avoid skin burns and unpredictable energy deposition patterns, especially when heating tumors closer to the surface of the liver. It should be noted that this collimation and high operating frequency (6)(7)(8) precludes the possibility of using phasing strategies between applicators for focusing energy, which is possible with MW applicators.…”

Section: Discussionmentioning

confidence: 99%

“…[4][5][6][7] Thermochemical ablation and irreversible electroporation have recently emerged as other modalities for tissue ablation. [8][9][10][11] Irrespective of energy modality, the goal of thermal ablation treatment of liver tumors is to raise target (tumor and a 5-10 mm margin encompassing the tumor) temperatures to lethal levels, while ensuring thermal protection of surrounding critical structures. If a single ablation does not adequately cover the target, sequential overlapping ablations must be performed until the entire target is treated adequately.…”

Section: Introductionmentioning

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: Introductionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

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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“…The most frequently used energy sources include radio frequency, microwaves, lasers, and cryoablation. 1,2 Thermochemical ablation 3 and irreversible electroporation 4 have recently emerged as other modalities for tissue ablation. High intensity focused ultrasound offers the potential for image-guided noninvasive treatment of deep targets.…”

Section: Introductionmentioning

confidence: 99%

Microwave ablation at 915 MHz vs 2.45 GHz: A theoretical and experimental investigation

et al. 2015

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“…Determining the heat transfer for such applications usually involves one or more of the following methods: direct in vivo temperature measurement [1,2], numerical modeling [3][4][5], and in vitro modeling using tissue phantoms [6][7][8][9]. In vivo measurements have obvious availability issues and can explore only a limited region of parameter space, while some scenarios require additional coupled processes that are not accurately incorporated computationally (e.g., bacterial cultures).…”

Section: Introductionmentioning

confidence: 99%

Poly(vinyl alcohol) tissue phantoms as a robustin vitromodel for heat transfer

Coffel

Nuxoll

2016

International Journal of Polymeric Materials and Polymeric Biom

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Glutaraldehyde-crosslinked poly(vinyl alcohol) (PVA) was used to create pourable, volume-stable hydrogel tissue phantoms that demonstrate several advantages over traditional poly(acrylamide) phantoms. The crosslinker concentration, curing time, and curing temperature were tuned to produce a tissue phantom whose volume varied by <0.2% over a 25-day span. The thermal conductivity of the PVA phantoms was tuned across the physiological range from 0.475 to 0.795 W m À 1°CÀ 1 by incorporating inert particle fillers. Experimental thermal diffusivity trials demonstrated the method's utility for creating reliable, versatile tissue phantoms for the in vitro study of heat transfer in biologically relevant scenarios. GRAPHICAL ABSTRACT ARTICLE HISTORY

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Concentration and volume effects in thermochemical ablation in vivo: Results in a porcine model

Cited by 22 publications

References 38 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

Microwave ablation at 915 MHz vs 2.45 GHz: A theoretical and experimental investigation

Poly(vinyl alcohol) tissue phantoms as a robustin vitromodel for heat transfer

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