Effect of variable heat transfer coefficient on tissue temperature next to a large vessel during radiofrequency tumor ablation

Santos, Ícaro dos; Haemmerich, Dieter; Pinheiro, Cleber da Silva; Rocha, Adson Ferreira da

doi:10.1186/1475-925x-7-21

Cited by 55 publications

(39 citation statements)

References 35 publications

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“…Measured tissue temperatures above 90°C within the heated zone are in favor of this hypothesis. However, the situation may be different for target tissue directly adjacent to vessels, where cooling mechanisms proceed faster (27,28).…”

Section: Discussionmentioning

confidence: 99%

Prediction of cell necrosis with sequential temperature mapping after radiofrequency ablation

Rempp

Clasen

Boss

et al. 2009

Magnetic Resonance Imaging

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Purpose:To assess the feasibility of magnetic resonance (MR) thermometry after thermoablative therapy and to quantitatively evaluate the ability of two sequence types to predict cell necrosis. Methods:Twenty patients with hepatic tumors were treated by MR-guided radiofrequency ablation. For each 10 patients, postinterventionally performed gradient echo and segmented echo planar imaging sequences were used to calculate temperature maps based on the proton resonance frequency shift method. Contrast-enhanced images acquired 1 month after therapy were registered on the temperature maps and the necrotic, nonenhanced area was segmented and compared to the area with a displayed temperature above 60°C. Sensitivity and positive predictive value of the temperature map was calculated, using the follow-up imaging as the gold standard. Results:Temperature mapping reached acceptable image quality in 45/47 cases. Sensitivity, ie, the rate of correctly detected coagulated tissue was 0.82 Ϯ 0.08 for the gradient echo imaging (GRE) sequence and 0.81 Ϯ 0.14 for the echo planar imaging (EPI) sequence. Positive predictive value, ie, the rate of voxel in the temperature map over 60°C that actually developed necrosis, was 0.90 Ϯ 0.07 for the GRE sequence and 0.84 Ϯ 0.11 for the EPI sequence. Conclusion:Sequential MR temperature mapping allows for the prediction of the coagulation zone with an acceptable sensitivity and positive predictive value using EPI and GRE sequences. REAL-TIME TEMPERATURE MAPPING of magnetic resonance (MR)-guided minimally invasive radiofrequency (RF) ablation has been shown to be feasible both ex vivo (1) and in vivo (2-5), and has the potential of becoming the gold standard for therapy monitoring of thermoablative therapies. Different MR techniques have been proposed for temperature measurement (6 -10); the most frequently used is the proton resonance frequency shift (PRF) method (11-14), which is based on a temperature-dependent phase shift allowing for the measurement of temperature changes relative to a baseline image. With frequent repetitive measurements during thermoablative therapy, this approach allows a precise estimation of the lethal thermal dose (15) based on the Arrhenius model (16,17) and could be used to predict the size and position of the coagulation zone in animal studies (3,5). Furthermore, real-time temperature monitoring could allow for visualizing a vessel-related cooling effect and thus prevent a survival of cancer cells due to an undetected heat-sink effect.Due to technical and medical challenges linked to this approach, the majority of the literature up to now concerns preclinical questions. In case of RF ablation, the simultaneous use of an RF generator with frequencies between 300 and 500 kHz during imaging decreases image quality (6,18). To date, only noncommercial filters were used to overcome this problem (4,18) or generators with an adapted frequency were employed in animal studies (3,19). Therefore, we performed temperature measurement with a sequential approach: The sedated pat...

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Section: Discussionmentioning

confidence: 99%

Prediction of cell necrosis with sequential temperature mapping after radiofrequency ablation

Rempp

Clasen

Boss

et al. 2009

Magnetic Resonance Imaging

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“…To perform a conservative estimation of the equilibration time, the spore was assumed to be a uniform sphere of diameter D p with the lowest plausible thermal conductivity, k, and the highest plausible heat capacity. For the former, we used 0.05 W/m-K [listed for fiber glass which is less conductive than fat or other biological tissues (Santos et al, 2008)]; for the latter, we used 4.18 x 10 6 J/m 3 -K (water). The Biot number of such a spherical particle…”

Section: Thermal Equilibration Time Of a Spore In Heated Air Flowmentioning

confidence: 99%

Inactivation of Aerosolized Biological Agents using Filled Nanocomposite Materials

Grinshpun¹,

Schoenitz²,

Dreizin³

et al. 2013

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)2. REPORT TYPE 3. DATES COVERED (From -To) Approved for public release; distribution is unlimited.In this multi-institutional grant, a new method for inactivating aerosolized biological agents was developed utilizing a new class of energetic materials: filled nanocomposite materials. The implemented approach enabled a controllable release of iodine-based oxidizing species in the combustion environment to inactivate viable airborne bio-agents, such as stress-resistant bacterial spores and viruses. Composites with adjustable Al/I2 ratios were produced. A state-of-the-art experimental facility was developed for studying how novel energetic formulations and their combustion products affect the viability of aerosolized spores and viruses during a short (< 1 s) exposure times. Controlled bioaerosol dispersal and sample collection protocols were developed and optimized. The dry-heat inactivation of aerosolized spores was quantified separately from chemical effects and linked to DNA repair mechanisms. It was concluded that the iodine-containing powder provided significantly more effective inactivation of airborne spores than non-iodinated powders. The results of this research help to better understand physical, physicochemical, and biological properties associated with inactivation of aerosolized bio-agents in combustion environments.Bioaerosol inactivation, spore, virus, bio-agent defeat, energetic material, iodine 1.000 000 x E -10 1.013 25 x E +2 1.000 000 x E +2 1.000 000 x E -28 1.054 350 x E +3 4.184 000 4.184 000 x E -2 3.700 000 x E +1 1.745 329 x E -2 t k = (t o f + 459.67)/1.8 1.602 19 x E -19 1.000 000 x E -7 1.000 000 x E -7 3.048 000 x E -1 1.355 818 3.785 412 x E -3 2.540 000 x E -2 1.000 000 x E +9 1.000 000 4.183 4.448 222 x E +3 6.894 757 x E +3 1.000 000 x E +2 1.000 000 x E -6 2.540 000 x E -5 1.609 344 x E +3 2.834 952 x E -2 4.448 222 1.129 848 x E -1 1.751 268 x E +2 4.788 026 x E -2 6.894 757 4.535 924 x E -1 4.214 011 x E -2 1.601 846 x E +1 1.000 000 x E -2 2.579 760 x E -4 1.000 000 x E -8 1.459 390 x E +1 1. ABSTRACTIn this multi-institutional grant, a new method for ...

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“…The classical bio-heat equation, the Pennes model, has been widely used in the literature to model the electrical-thermal heating process during the ablation procedure [4][5][6]. However, the convective heat-transfer term between tissue and blood in the equation is oversimplified, assuming the blood to be a volumetric heat sink and one that is uniformly distributed throughout the tissue [7].…”

Section: (A) Bio-heat Modelmentioning

confidence: 99%

“…For this, we have proposed a novel three-state model, outlined in more detail by O'Neill et al [17], extending the existing models that are predominantly based on two states (alive and dead). This three-state model includes an intermediate compartment between the fully alive (A) and dead (D) compartments, which we term the vulnerable (V ) state, 4) where transitions between the states are governed by (temperature-dependent) forward and (temperature-independent) backward rate constants, and A, V and D represent the fraction of cells within each state at each point in the tissue. While most of the literature (see [18] for a very thorough review) uses Arrhenius-based rate coefficients, as proposed by early workers in this area, such as Henriques and Moritz for cutaneous skin burns [19][20][21], the nature of this exponential form, where the transition rate is proportional to the exponential of the activation energy divided by temperature, results in a highly sensitive constant of proportionality where reported values range over tens of orders of magnitude [18].…”

Section: (B) Cell Death Modelmentioning

confidence: 99%

Image-based multi-scale modelling and validation of radio-frequency ablation in liver tumours

Payne

Flanagan²,

Pollari

et al. 2011

Phil. Trans. R. Soc. A.

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The treatment of cancerous tumours in the liver remains clinically challenging, despite the wide range of treatment possibilities, including radio-frequency ablation (RFA), highintensity focused ultrasound and resection, which are currently available. Each has its own advantages and disadvantages. For non-or minimally invasive modalities, such as RFA, considered here, it is difficult to monitor the treatment in vivo. This is particularly problematic in the liver, where large blood vessels act as heat sinks, dissipating delivered heat and shrinking the size of the lesion (the volume damaged by the heat treatment) locally; considerable experience is needed on the part of the clinician to optimize the heat treatment to prevent recurrence. In this paper, we outline our work towards developing a simulation tool kit that could be used both to optimize treatment protocols in advance and to train the less-experienced clinicians for RFA treatment of liver tumours. This tool is based on a comprehensive mathematical model of bio-heat transfer and cell death. We show how simulations of ablations in two pigs, based on individualized imaging data, compare directly with experimentally measured lesion sizes and discuss the likely sources of error and routes towards clinical implementation. This is the first time that such a 'loop' of mathematical modelling and experimental validation in vivo has been performed in this context, and such validation enables us to make quantitative estimates of error.

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Effect of variable heat transfer coefficient on tissue temperature next to a large vessel during radiofrequency tumor ablation

Cited by 55 publications

References 35 publications

Prediction of cell necrosis with sequential temperature mapping after radiofrequency ablation

Prediction of cell necrosis with sequential temperature mapping after radiofrequency ablation

Inactivation of Aerosolized Biological Agents using Filled Nanocomposite Materials

Image-based multi-scale modelling and validation of radio-frequency ablation in liver tumours

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