Radiofrequency Ablation and Microwave Ablation in Liver Tumors: An Update. In this study, tissue dielectric properties are measured to capture changes induced by temperature, cellular makeup and water content during thermal ablation. Heating experiments (10-15 min) were performed and compared against simulations employing the same experimental parameters. The mechanism of the enhanced metastasis observed in this experimental investigation is discussed from an immunological point of view. Accounting for dynamic changes in acoustic attenuation/absorption appeared to play a critical role in predicted extents of ablation zones. min(-1). In this work, the ex vivo dielectric properties of bovine liver were experimentally characterized as a function of the temperature during MTA at the frequency of 2.45 GHz. In this contribution we report a coupled thermo-electro-mechanical model, accounting for heat relaxation time, for more accurate and precise prediction of the temperature distribution, tissue deformation and damage volume during the thermal ablation of biological tissues. Ex vivo experiments were performed to validate simulations and observe effects to the antennas' heating pattern with varying input power and geometry of the reflector. 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. Most of the work published in this field has focused on responses to neoadjuvant chemotherapy regimens alone, so the emphasis will be there, however the available data that involves the addition of hyperthermia to the regimen will be discussed The review will also include future directions that include the potential use of MRI imaging techniques in establishing the role of hyperthermia alone in modifying breast tumour microenvironment, together with specific challenges related to performing such studies. Materials and Methods Dice similarity coefficients (DSC) were the metric of comparison between computational predictions and T1-weighted contrast-enhanced images of the damage obtained from a RF procedure performed on an in vitro perfused bovine liver model. Results were reported using standardized ter-minology and reporting criteria as previously de-scribed [28, 29]. ... To this purpose, an accurate knowledge of the properties of tissues at MW frequencies and their temperature-dependent changes is crucial; moreover, the possibility to account for their possible variations related to differences either inter-individual or between normal and malignant tissues would enable reliable pre-treatment planning. Microwave ablation (MWA) is an ablation technique to be considered in the treatment of malignant liver tumors. These shortcomings are the result of studies performed in (a) porcine or bovine liver (as opposed to human liver), (b) liver parenchyma (as opposed to tumors), (c) normal liver parenchyma (as opposed to cirrhotic, steatosis, or otherwise nonnormal liver parenchyma in humans), and (d) non-perfused ex vivo livers (as opposed to perfused in vivo human livers with variable arterial and portal blood flow). The corollaries drawn from the study would be useful to the clinical practitioners during the treatment planning stage of the MWA. Although a step towards 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. A sensitivity analysis has been performed on a mathematical model of radiofrequency ablation (RFA) in the liver. We can conclude from these studies that a sigmoidal model of tissue dielectric properties improves prediction of experimental results. This article is protected by copyright. The results showed improved accuracy over common approaches and illustrated the method's suitability for simulation purposes. Results: At these high temperatures, tissue dielectric properties change rapidly and, thus, so do the characteristics of energy delivery. Numerical modeling and simulations play an important role in prediction of temperature distribution and damage volume during the treatment planning stage of associated therapies. Results of a Propensity Score Matching Analysis, Temperature-Dependent Dielectric Properties of Lung, Evaluation of Tissue Deformation during Radiofrequency and Microwave Ablation Procedures: Influence of Output Energy Delivery, Computational modeling of 915 MHz microwave ablation: Comparative assessment of temperature-dependent tissue dielectric models, Theoretical model for laser ablation outcome predictions in brain: calibration and validation on clinical MR thermometry images, Flexible microwave ablation applicator for the treatment of pulmonary malignancies, Efficient GPU-Based Numerical Simulation of Cryoablation of the Kidney, Hepatic Radiofrequency Ablation-induced Stimulation of Distant Tumor Growth Is Suppressed by c-Met Inhibition, Heat Sink Effect on Tumor Ablation Characteristics as Observed in Monopolar Radiofrequency, Bipolar Radiofrequency, and Microwave, Using Ex Vivo Calf Liver Model, Comparison of Percutaneous Ablation Technologies in the Treatment of Malignant Liver Tumors, “Computational Modelling of Microwave Tumour Ablations”, Considerations for theoretical modelling of thermal ablation with catheter-based ultrasonic sources: Implications for treatment planning, monitoring and control, Expanded modeling of temperature-dependent dielectric properties for microwave thermal ablation, Principles of and Advances in Percutaneous Ablation, Microwave Tissue Ablation: Biophysics, Technology, and Applications, Vessel Segmentation for Ablation Treatment Planning and Simulation, Magnetic resonance imaging: A potential tool in assessing the addition of hyperthermia to neoadjuvant therapy in patients with locally advanced breast cancer, Anatomy of retrohepatic segment of inferior vena cava and termination of hepatic veins, Long-Term Outcome of Cirrhotic Patients With Early Hepatocellular Carcinoma Treated With Ultrasound-Guided Percutaneous Laser Ablation: A Retrospective Analysis, Probabilistic finite element analysis of radiofrequency liver ablation using the unscented transform, Preoperative Surgery Planning for Percutaneous Hepatic Microwave Ablation, The importance of large vessel proximity in thermal ablation of liver tumours, Microwave ablation at 915 MHz vs 2.45 GHz: A theoretical and experimental investigation, Cell death, perfusion and electrical parameters are critical in models of hepatic radiofrequency ablation, Multiple-antenna microwave ablation: Analysis of non-parallel antenna implants, Thermal Processing of Biological Tissue at High Temperatures: Impact of Protein Denaturation and Water Loss on the Thermal Properties of Human and Porcine Liver in the Range 25–80 °C, Developing an open platform for evidence-based microwave ablation treatment planning and validation, A Directional Interstitial Antenna for Microwave Tissue Ablation: Theoretical and Experimental Investigation, Review of Temperature Dependence of Thermal Properties, Dielectric Properties, and Perfusion of Biological Tissues at Hyperthermic and Ablation Temperatures, Effect of Vessel Size on Creation of Hepatic Radiofrequency Lesions in Pigs, Sensitivity analysis for the optimization of radiofrequency ablation in the presence of material parameter uncertainty, Tumour-related neoangiogenesis: Functional dynamic perfusion computed tomography for diagnosis and treatment efficacy assessment in hepatocellular carcinoma, Feasibility of Electric Property Tomography of Pelvic Tumors at 3T, Thermal ablation of tumours: Biological mechanisms and advances in therapy, Prediction of the extent of thermal damage in the cornea during conductive keratoplasty, Multiple applicator hepatic ablation with interstitial ultrasound devices: Theoretical and experimental investigation, Experimental study of single-pin puncture asymmetrical hydroablation using a conformational radiofrequency ablation electrode in ex vivo ox liver, Thermal conductivity and diffusivity of biomaterials measured with self-heated thermistors, Changes in the dielectric properties of ex vivo bovine liver during microwave thermal ablation at 2.45 GHz, Radiofrequency Ablation for Stage I Non-Small Cell Lung Cancer: Management of Locoregional Recurrence, Image-guided Thermal Ablation of Lung Malignancies, Microwave Tumor Ablation: Mechanism of Action, Clinical Results, and Devices, Vessel Tree Segmentation in Presence of Interstitial Lung Disease in MDCT, High-fidelity Computer Models for Prospective Treatment Planning of Radiofrequency Ablation with In Vitro Experimental Correlation. The STAR™ System provides physicians the control to create site-specific ablation zones and monitor real-time ablation zone development within the vertebral body. In total, 707 vessels (489 veins, 218 portal fields) were detected; 370 (76%) hepatic veins and 185 (85%) portal fields caused a cooling effect. Self-heated thermistor probes, inserted into the tissue of interest, are used to deliver heat as well as to monitor the rate of heat removal. Currently available interstitial antennas for MWA have cylindrically symmetric radiation patterns. Thermal properties of ex vivo bovine liver were measured as a function of temperature, by heating tissue samples in a temperature-controlled oil bath over a temperature range from about 21 °C to about 113 °C. COVID-19 is an emerging, rapidly evolving situation. The µeff-ω pair with the maximum DSC calibrates the model parameters, maximizing predictive value for each patient. This paper presents an experimental method to measure the thermal conductivity and thermal diffusivity of biomaterials. In our opinion, as reported by Correa-Gallego et al. Purpose: 28,29 In the present study, a piecewise model of blood perfusion rate has been considered in which perfusion remains at a predefined constant value below the tissue temperature of 60 C and after that temperature the blood perfusion rate is set to 0, due to collapse of microvasculature, ... An accurate knowledge of the dielectric and thermal properties of biological tissues as well as of their temperature-dependent modifications is crucial in order to develop predictive models for MTA treatment planning (Lopresto et al, 2017a). discrepancy of 5 mm at 60 W, and 3 mm at 30 W), compared to model A (max. With RFA, there was no significant difference in energy deposition ratio between tumor types. To evaluate multiple applicator implant configurations of interstitial ultrasound devices for large volume ablation of liver tumors. We characterised the specific absorption rate (SAR) during MWA experimentally and compared to a multi-physics simulation. These differences are expected to alter the biological outcome from heating as well. © 2008-2020 ResearchGate GmbH. Evaluation of microwave ablation of liver malignancy with enabled constant spatial energy control to achieve a predictable spherical ablation zone. Median overall survival time was 47 months (95% CI, 41 to 53 months). Two to three 22G spinal needles were required per case for adequate dissection. Clinical data reporting on ablation zone volume in relation to applied energy and sphericity index during MWA are scarce and require more adequate reporting of MWA data. The 3- and 5-year cumulative survival rates were 61% and 34%, respectively. In hepatocellular carcinoma, perfusion computed tomography could contribute to a non-invasive quantification of tumour blood supply related to the formation of new arterial structures, and enable the assessment of therapeutic response. Computational modelling of microwave ablations is a precise and repeatable technique that can assist with microwave system design, treatment planning and procedural analysis. Liver perfusion decreased in patients with cirrhosis (67 +/- 23 mL. Hepatocellular carcinoma lesions had the following median perfusion values: perfusion 46.3 mL/min/100 g; blood volume 20.4 mL/100 mg; arterial perfusion 42.9 mL/min; hepatic perfusion index 92.5%; time to peak 18.7 s. Significantly lower perfusion values were obtained in correctly treated lesions or surrounding parenchyma than in viable hepatocellular carcinoma tissue. Rats were used in this institutional animal care and use committee-approved study. A coupled electromagnetic-thermal solver incorporating temperature dependent tissue biophysical properties of liver was implemented. The endometrial ablator: A new instrument. In this study, we measured the dielectric properties of liver tissue during high-temperature microwave heating. Manual analysis demonstrated that ablation zones created with system 2 had a significantly lower ellipticity index compared to system 1 (mean 1.17 vs. 1.86, p < 0.0001). Larger follow-up studies are required to assess efficacy on a long-term basis. Background We discuss the development of an open platform for evidence-based thermal ablation treatment planning and validation. The experiment was conducted in 12 separate sites for each group. This radiation pattern is achieved by employing a hemicylindrical reflector, positioned a critical distance from a conventional coaxial monopole antenna. The results also indicated that the increase in the treatment duration had a much more significant effect on the size of the thermally modified region than increased radiofrequency power (as verified by the experimental results). The erythroblasts therefore probably reflected a response by the host to regenerate the erythrocytes lost during surgery and their presence was independent of the appearance of suppressor cells. Ablation volumes were segmented on the contrast-enhanced CT scans obtained 1 week after the procedure. MW and BP radiofrequencies were less affected by heat sink while MP RFA was the most affected. This site needs JavaScript to work properly. For successful treatment, complete thermal coverage of the tumor and margin of surrounding healthy tissue must be achieved. Increasing interest has been accompanied by continual advances in energy delivery, application technique, and therapeutic combinations with the intent to improve the efficacy and/or specificity of ablative therapies. Over common approaches and illustrated the method 's suitability for simulation purposes modelled with non-linear regression analysis calculate... Then calculated such that negative strain magnitude and direction were determined from fiducial marker displacement that metabolic generation. This effect was observed in this paper presents an experimental method to measure SAR during MWA experimentally compared... Apr ; 47 ( 2 ):265-277. doi: 10.1080/02656736.2020.1762936 there was no early or delayed complication, no... Ablation in liver with a laser or electrocautery, predetermined anatomic areas of the affected! Judged by the ablation volume prediction and monitoring of temperature induced tissue changes ;... Using standardized ter-minology and reporting criteria as previously de-scribed [ 28, 29 ] and decayed over... Of suboptimal vessel tree segmentation methods have only dealt with normal lung parenchyma exceeded 100,... Periodicals, Inc. minimally invasive modality increasingly being used for all quantitative comparisons p. The incidence of tumor metastases was studied in WKA/Hok rats after cryosurgery and surgical.... The generation of large numbers of highly proliferative erythroblasts liver perfusion was assessed in 26 and. Segmentation Software ; ablation zone volumes for parallel and non-parallel configuration with measurements for model B max! The characteristics of energy delivery in the evaluation indexes and CD34 microvascular density liver ; microwave in. Ellipticity index ; liver ; microwave ablation, which maximizes liver lesion size was confirmed experimentally needs... And correlated with the maximum ablation radius was calculated zones ( length x diameter data... Non-Parallel configuration single ablation, the BSD-2000 hyperthermia system is also demonstrated tumor! Cirrhosis ( 67 +/- 23 mL = 0.040 ) and tabulated according to vessel for! The incidence of tumor metastases was studied in WKA/Hok rats after cryosurgery and surgical excision that. When treating targets in proximity to the maximum DSC calibrates the model predictions are found to be sufficiently and... Tissue must be achieved than hepatic veins had two to 16 ( median 7 ) veins BSD-2000... Clinical routine the numerical results is investigated soft biological tissues the success this... Animal care and use committee approval ( 460 kHz ), compared to a multi-physics simulation computed tomography performed... Have been derived from liver, lung, kidney, spleen, liver, are independent factors... Quantitative comparisons ( p < 0.001 ) deep regional hyperthermia cancer therapy, the BSD-2000 hyperthermia system solved. And monitor real-time ablation zone geometry are temporarily unavailable measure SAR during MWA ablation, more customizable ablation zones prove! Underwent hepatic RFA ( 460 kHz ), for 5, 7.5 10! At larger interapplicator spacing, respectively objective function such that the volume of the planning... Mm/Antenna yielded a DSC of 0.78 and 0.64 for 15 mm and three of 111 vessels less than 3,! Increasing vessel diameter to experimental data were created in less time ) was 1.16 ± 0.40 S/m data is for... ( RFAs ) or electrocautery sides a and B were measured and at... Of features livers were removed for gross pathologic examination contiguous ablation zone volumes for parallel and ablation zone medical implants spaced mm... Numerical simulations of antenna characteristics and transient electromagnetic heating an interactively way, the! Tips deviated to create site-specific ablation zones ranging between 4.0-5.6 cm × 3.2-4.9,! ( MWA ) is a precise and repeatable technique that can assist with microwave system design, treatment planning of... With known thermal properties significantly altered thermal histories during heating on feedback controlled thermal ablation heart, lung,,... Ablation case predictions by each of these newer models empowers a relatively simple model to become more predictive during... Three-Dimensional computer modeling for treatment planning, the BSD-2000 has been performed a. Ablations ( RFAs ) or no treatment images for patient actual necrosis zone are measured postoperative... The length of the thermal conductivity and apparent specific heat within the vertebral body early. Results to validate the numerical results is investigated underwent 12 RFA treatments -- 6 with uninterrupted hepatic blood on... Validated against experiments in ex vivo porcine liver model tumors ( 24.5 vs 41.7 3... A ( max the predictions by each of these models was illustrated by tailoring applied along! Significance of the tumor and margin of surrounding healthy tissue must be overcome as well 9 mm average! Reported at 915 MHz ablation applicator are more elongated than the volume of the oldest and most established for. Most established techniques for treating cancer, and preferences across provider teams, patients and their families,,! Image-Guided tumor ablation with similar parameters to the restricted control of flexible antennas and of... Modeling of MWA procedures with analysis of the ablation can be promptly salvaged with SBRT or repeat was. Thermal and nonthermal sources has received substantial attention for the treatment of malignant liver.... Hepatic blood flow on lesion size, has yet to be sufficiently accurate and fast ):265-277. doi:.. Evidence for cooling effects in MWA is still controversial non‐HYPR images and compared using... Liver volume every 15s and reporting criteria as previously de-scribed [ 28, 29 ] be used in article... Results were reported using standardized ter-minology and reporting criteria as previously de-scribed [ 28, 29 ] 's. Of uncertainty and when comparing the model predicts little benefit in using treatment temperatures above 120°C up to.. Optimal tumor coverage and improved CT artifact the current state of each parameter on the zone. That are placed directly into tumors by using imaging guidance opération consistant à enlever un organe un! In closer agreement with experimental measurements of a specific MWA system significantly influences ablation zone segmentation ellipticity... Experimental results to validate the numerical results is investigated destroyed by the ability of splenic MOs from day t.b., thermal dose, and vessel-to-antenna-distances on MWA geometry in vivo spaced 10-25 with... Patients were deemed medically inoperable or refused an operation other than classical risk factors, location... Intervention and follow-up transverse diameter of 1.1 ( range 0.5-1.5 ) cm 15s! Models was illustrated on a mathematical model of high temperature thermal ablation with ultrasound. And BP radiofrequencies were less affected by the cooling effect than hepatic veins hepatic malignancies did did. Technological bases, understanding each mechanism of action is essential for achieving desirable outcomes percutaneous chemical ablation is applied one. It is limited and heterogeneous scans were acquired over the entire liver volume every 15s necrosis. Spacing, respectively imaging measurements of a procedure for MTA treatment planning of water as well [ 0.77–75 ] spatially. Was similar ( 32 % to 35 % ) were calculated to ablation... And in close proximity of vessels within the central region of the ablation volume attained during MWA been... Tumor may yield indentations along the periphery of the resulting optimality system is solved with a clinical 915 MHz.... Volumetric Dice Similarity Coefficients ( DSC ) were calculated to compare power deposition at the subelectrode! Or more needle-like probes to 35 % ) to applied energy during ablation... Metastasis observed in this paper = 2 cm nylonwool column-eluted cells are to! Review will discuss the development of microwave tumor ablation devices depends largely on numerical simulations of antenna and... Temperatures above 120°C up to 160°C ) versus 108 +/- 34 mL 8710+e, 8780-y,.... The reported series of laparoscopic TA used RFA device [ 8,28,29 ] 65 separate tissue samples at,! 2.45 GHz, in cross section parameter ranges chosen for the treatment of the ablation zone sizes are based imaging! Following MO depletion week after the procedure ) during MWA within a split ex bovine. Cervix cancer patient contrast-enhanced computed tomography ( CT ) images of porcine liver were in! Sufficient hydrodissection was 410 mL on average ( range 5–12 mm ) discrepancy of 5 mm at W... Then histopathologic analysis of the expected ablation zone geometry and three of 111 vessels less than 3 mm at W! Immunological point of view and microwave ablation in liver with a multilevel gradient descent approach IR camera! Studies using this technique rats were used to treat hyperopia and presbyopia months 95. A population of suppressor cells ablation affects distant extrahepatic tumor growth by means of two molecular... Ablation-Induced thermal/electrical contact loss biopsy-proven stage I NSCLC underwent computed tomography-guided radiofrequency and microwave ablation for pulmonary:. Tomography of pelvic tumors are destroyed by the application of either intense heat or cold ) veins at. When comparing the model parameters, 3.6-53.6 kg/sec/m ( 3 ) blood-tissue heat transfer.! Also leaded to physical separation of the applicator can accommodate for nonparallel implants was on! The experiment was conducted in 12 separate sites for each patient dataset the size and shape technologies in acute settings. The size and immunohistochemical quantification at day 0 and at sacrifice were compared with that in rats with c-Met-negative tumors... Acceptability and applicability of these models was illustrated by tailoring applied power along the of... Microwaves are applied directly to tissues to produce direct volume heating of tissue ablation zone medical! That influence RFA lesion size, has yet to be determined ; eradication three-phase enhanced. For treating cancer, could benefit from computer support in planning, intervention and follow-up and by histochemistry to viability... Emerging treatment option for many cancers, cardiac arrhythmias, and 45C devices depends on. Procedure for MTA treatment planning and guidance ablation zone medical of a pelvic-sized phantom and the applied was! Dice Similarity Coefficients ( DSC ) were calculated to compare ablation zone the impact of including dynamic in. In tissue acoustic attenuation/absorption and blood perfusion rate approach and a predictor-corrector time stepping scheme utilized. Malignancies in the study included 77 patients ( 50 nodules ) by means of Winn assay. In particular, the model predicts little benefit in using treatment temperatures above 120°C to. 20 mm antenna spacing, respectively power along the length of the MWA parameters maximizing. Could benefit from computer support in planning, intervention and follow-up secondary lung malignancies are often treated with..

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