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Radiofrequency ablation for liver tumors abutting complex blood vessel structures: treatment protocol optimization using response surface method and computer modeling. Int J Hyperthermia 2022; 39:733-742. [PMID: 35610101 DOI: 10.1080/02656736.2022.2075567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
OBJECTIVE To achieve a result of a large tumor ablation volume with minimal thermal damage to the surrounding blood vessels by designing a few clinically-adjustable operating parameters in radiofrequency ablation (RFA) for liver tumors abutting complex vascular structures. METHODS Response surface method (RSM) was employed to correlate the ablated tumor volume (Ra) and thermal damage to blood vessels (Dt) based on RFA operating parameters: ablation time, electrode position, and insertion angle. A coupled electric-thermal-fluid RFA computer model was created as the testbed for RSM to simulate RFA process. Then, an optimal RFA protocol for the two conflicting goals, namely (1) large tumor ablation and (2) small thermal damage to the surrounding blood vessels, has been achieved under a specific ablation environment. RESULTS Linear regression analysis confirmed that the RFA protocol significantly affected Ra and Dt (the adjusted coefficient of determination Radj2 = 93.61% and 95.03%, respectively). For a proposed liver tumor scenario (liver tumor with a dimension of 4×3×2.9 cm3 abutting a complex vascular structure), an optimized RFA protocol was found based on the regression results in RSM. Compared with a reference RFA protocol, in which the electrode was centered in the tumor with a 12-min ablation time, the optimized RFA protocol has increased Ra from 98.1% to 99.6% and decreased Dt from 4.1% to 0.4%, achieving nearly the complete ablation of proposed liver tumor and ignorable thermal damages to vessels. CONCLUSION This work showed that it is possible to design a few clinically-adjustable operating parameters of RFA for achieving a large tumor ablation volume while minimizing thermal damage to the surrounding blood vessels.
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Fang Z, Moser M, Zhang E, Zhang WJC, Zhang B. Design of a Novel Electrode of Radiofrequency Ablation for Large Tumors: In Vitro Validation and Evaluation. J Biomech Eng 2018; 141:2718212. [PMID: 30516246 DOI: 10.1115/1.4042179] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Indexed: 11/08/2022]
Abstract
In the present study, a monopolar expandable electrode (MEE) in radiofrequency ablation (RFA) proposed in our previous study was validated and evaluated using the in vitro experiment and computer simulation. Two commercial RF electrodes (conventional electrode, CE and umbrella electrode, UE) was used to compare the ablation results with MEE using the in vitro egg white model (experiment and computer simulation) and in vivo liver tumor model (computer simulation) to verify the efficacy of MEE in the large tumor ablation. The sharp increase in impedance during RFA procedures was taken as the termination of RFA protocols. The volume and sphericity of ablation zone generated by MEE, CE, and UE in the in vitro egg white experiment were 75.3 1.6 cm3, 2.7 0.4 cm3, 12.4 1.8 cm3 (P <0.001), and 88.1 0.9%, 12.9 1.3%, 62.0 3.0% (P <0.001), respectively. Correspondingly, a similar result was obtained in the egg white simulation. In the liver tumor simulation, the volume and sphpericity of ablation zone generated by MEE, CE, and UE were 35.4 cm3 and 86.8%, 3.7 cm3 and 17.7%, and 12.7 cm3 and 59.6%, respectively. In summary, MEE has the potential to achieve complete ablation in the treatment of large tumors (>3 cm in diameter) compared with CE and UE due to the larger electrode-tissue interface and more round shape of hooks.
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Affiliation(s)
- Zheng Fang
- School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Michael Moser
- Department of Surgery, University of Saskatchewan, Saskatoon, SK S7N 0W8, Canada
| | - Edwin Zhang
- Division of Vascular & Interventional Radiology, Department of Medical Imaging, University of Toronto, ON M5T 1W7, Canada
| | - W J Chris Zhang
- Fellow ASME, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Bing Zhang
- Mem. ASME, Tumor Ablation Group, Biomedical Science and Technology Research Center, School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200444, China
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Xu A, Zhang L, Yuan J, Babikr F, Freywald A, Chibbar R, Moser M, Zhang W, Zhang B, Fu Z, Xiang J. TLR9 agonist enhances radiofrequency ablation-induced CTL responses, leading to the potent inhibition of primary tumor growth and lung metastasis. Cell Mol Immunol 2018; 16:820-832. [PMID: 30467420 DOI: 10.1038/s41423-018-0184-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 10/25/2018] [Indexed: 12/11/2022] Open
Abstract
Radiofrequency ablation (RFA) is the most common approach to thermal ablation for cancer therapy. Unfortunately, its efficacy is limited by incomplete ablation, and further optimization of RFA is required. Here, we demonstrate that incubation at 65 °C triggers more EG7 tumor cell death by necrosis than treatment at 45 °C, and the 65 °C-treated cells are more effective at inducing antigen-specific CD8+ cytotoxic T lymphocyte (CTL) responses after injection in mice than the 45 °C-treated ones. Dendritic cells (DCs) that phagocytose 65 °C-treated EG7 cells become mature with upregulated MHCII and CD80 expression and are capable of efficiently inducing effector CTLs in mouse tumor models. RFA (65 °C) therapy of EG7 tumors induces large areas of tumor necrosis and stimulates CTL responses. This leads to complete regression of small (~100 mm3) tumors but fails to suppress the growth of larger (~350 mm3) tumors. The administration of the Toll-like receptor-9 (TLR9) agonist unmethylated cytosine-phosphorothioate-guanine oligonucleotide (CpG) to DCs phagocytosing 65 °C-treated EG7 cells enhances the expression of MHCII and CD40 on DCs as well as DC-induced stimulation of CTL responses. Importantly, the intratumoral administration of CpG following RFA also increases the frequencies of tumor-associated immunogenic CD11b-CD11c+CD103+ DC2 and CD11b+F4/80+MHCII+ M1 macrophages and increases CD4+ and CD8+ T-cell tumor infiltration, leading to enhanced CD4+ T cell-dependent CTL responses and potent inhibition of primary RFA-treated or distant untreated tumor growth as well as tumor lung metastasis in mice bearing larger tumors. Overall, our data indicate that CpG administration, which enhances RFA-induced CTL responses and ultimately potentiates the inhibition of primary tumor growth and lung metastasis, is a promising strategy for improving RFA treatment, which may assist in optimizing this important cancer therapy.
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Affiliation(s)
- Aizhang Xu
- Cancer Research, Saskatchewan Cancer Agency, University of Saskatchewan, Saskatoon, SK, Canada.,Department of Oncology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Lifeng Zhang
- Department of General Surgery, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Jingying Yuan
- Cancer Research, Saskatchewan Cancer Agency, University of Saskatchewan, Saskatoon, SK, Canada.,Department of Oncology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Fatma Babikr
- Cancer Research, Saskatchewan Cancer Agency, University of Saskatchewan, Saskatoon, SK, Canada.,Department of Oncology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Andrew Freywald
- Department of Pathology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Rajni Chibbar
- Department of Pathology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Michael Moser
- Department of Surgery, University of Saskatchewan, Saskatoon, SK, Canada
| | - Wenjun Zhang
- Department of Bioengineering, University of Saskatchewan, Saskatoon, SK, Canada
| | - Bing Zhang
- Biomedical Science and Technology Research Center, School of Mechatronic Engineering and Automation, Shanghai University, Shanghai, China
| | - Zhaoying Fu
- Department of Immunology, College of Medicine, Yian-An University, Yian-An, China
| | - Jim Xiang
- Cancer Research, Saskatchewan Cancer Agency, University of Saskatchewan, Saskatoon, SK, Canada. .,Department of Oncology, University of Saskatchewan, Saskatoon, SK, Canada.
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Fang Z, Zhang B, Moser M, Zhang E, Zhang W. Design of a Novel Electrode of Radiofrequency Ablation for Large Tumors: A Finite Element Study. ACTA ACUST UNITED AC 2017. [DOI: 10.1115/1.4038129] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The aim of the study was to design a novel radiofrequency (RF) electrode for larger and rounder ablation volumes and its ability to achieve the complete ablation of liver tumors larger than 3 cm in diameter using finite element method. A new RF expandable electrode comprising three parts (i.e., insulated shaft, changing shaft, and hooks) was designed. Two modes of this new electrode, such as monopolar expandable electrode (MEE) and hybrid expandable electrode (HEE), and a commercial expandable electrode (CEE) were investigated using liver tissue with (scenario I) and without (scenario II) a liver tumor. A temperature-controlled radiofrequency ablation (RFA) protocol with a target temperature of 95 °C and an ablation time of 15 min was used in the study. Both the volume and shape of the ablation zone were examined for all RF electrodes in scenario I. Then, the RF electrode with the best performance in scenario I and CEE were used to ablate a large liver tumor with the diameter of 3.5 cm (scenario II) to evaluate the effectiveness of complete tumor ablation of the designed RF electrode. In scenario I, the ablation volumes of CEE, HEE, and MEE were 12.11 cm3, 33.29 cm3, and 48.75 cm3, respectively. The values of sphericity index (SI) of CEE, HEE, and MEE were 0.457, 0.957, and 0.976, respectively. The best performance was achieved by using MEE. In scenario II, the ablation volumes of MEE and CEE were 71.59 cm3 and 19.53 cm3, respectively. Also, a rounder ablation volume was achieved by using MEE compared to CEE (SI: 0.978 versus 0.596). The study concluded that: (1) compared with CEE, both MEE and HEE get larger and rounder ablation volumes due to the larger electrode–tissue interface and rounder shape of hook deployment; (2) MEE has the best performance in getting a larger and rounder ablation volume; and (3) computer simulation result shows that MEE is also able to ablate a large liver tumor (i.e., 3.5 cm in diameter) completely, which has at least 0.785 cm safety margin.
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Affiliation(s)
- Zheng Fang
- Tumor Ablation Group, CISR Center, East China University of Science and Technology, Shanghai 200237, China e-mail:
| | - Bing Zhang
- Mem. ASME Division of Biomedical Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9, Canada e-mail:
| | - Michael Moser
- Department of Surgery, University of Saskatchewan, Saskatoon, SK S7N 0W8, Canada e-mail:
| | - Edwin Zhang
- Division of Vascular and Interventional Radiology, Department of Medical Imaging, University of Toronto, Toronto, ON M5T 1W7, Canada e-mail:
| | - Wenjun Zhang
- Fellow ASME Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9, Canada e-mail:
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Current Solutions for the Heat-Sink Effect of Blood Vessels with Radiofrequency Ablation: A Review and Future Work. COMMUNICATIONS IN COMPUTER AND INFORMATION SCIENCE 2017. [DOI: 10.1007/978-981-10-6370-1_12] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Zhang B, Moser MAJ, Zhang EM, Luo Y, Zhang W. Numerical analysis of the relationship between the area of target tissue necrosis and the size of target tissue in liver tumours with pulsed radiofrequency ablation. Int J Hyperthermia 2015; 31:715-25. [PMID: 26360111 DOI: 10.3109/02656736.2015.1058429] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
PURPOSE Radiofrequency ablation (RFA) is currently restricted to the treatment of target tissues with a small size (<3 cm in diameter). To overcome this problem with RFA, some phenomena need to be understood first. The study presented in this paper investigated the relationship between the area of target tissue necrosis (TTN) and the size of target tissue in pulsed radiofrequency ablation (PRFA). MATERIALS AND METHODS Liver tumour, one of the common targets of RFA in clinical practice, was used as the target tissue in this study. Two types of pulsed RF power supply methods (half-square and half-sine) and three target tissues with different sizes (25 mm, 30 mm and 35 mm in diameter) were studied using finite element modelling. The finite element model (FEM) was validated by using an in vitro experiment with porcine liver tissue. The first roll-off occurrence or 720 s, whichever occurs first, was chosen as the ablation termination criterion in this study. RESULTS For each target tissue size, the largest TTN area was obtained using the maximum voltage applied (MVA) without roll-off occurrence. In this study, target tissues with a 25 mm diameter can be ablated cleanly but target tissues with 30-mm and 35-mm failed to be ablated. CONCLUSIONS The half-square PRFA could achieve a larger TTN area than the half-sine PRFA. The MVA decreases with an increase in the target tissue diameter in both the half-square PRFA and the half-sine PRFA. The findings of this study are in agreement with the clinical results that lesions (≥ 3 cm in diameter) have less favourable results from RFA.
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Affiliation(s)
- Bing Zhang
- a Division of Biomedical Engineering , University of Saskatchewan , Saskatoon , Canada
| | - Michael A J Moser
- b Department of Surgery , University of Saskatchewan , Saskatoon , Canada
| | - Edwin M Zhang
- c Department of Radiology and Diagnostic Imaging , University of Alberta , Edmonton , Canada
| | - Yigang Luo
- b Department of Surgery , University of Saskatchewan , Saskatoon , Canada
| | - Wenjun Zhang
- a Division of Biomedical Engineering , University of Saskatchewan , Saskatoon , Canada .,d Complex and Intelligent Systems Centre, School of Mechanical and Power Engineering, East China University of Science and Technology , Shanghai , China , and.,e Department of Mechanical Engineering , University of Saskatchewan , Saskatoon , Saskatchewan , Canada
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Zhang B, Moser MAJ, Zhang EM, Luo Y, Zhang H, Zhang W. Study of the relationship between the target tissue necrosis volume and the target tissue size in liver tumours using two-compartment finite element RFA modelling. Int J Hyperthermia 2015; 30:593-602. [PMID: 25430990 DOI: 10.3109/02656736.2014.984000] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
PURPOSE The aim of this study was to investigate the relationship between the target tissue necrosis volume and the target tissue size during the radiofrequency ablation (RFA) procedure. MATERIALS AND METHODS The target tissues with four different sizes (dxy = 20, 25, 30 and 35 mm) were modelled using a two-compartment radiofrequency ablation model. Different voltages were applied to seek the maximum target tissue necrosis volume for each target tissue size. The first roll-off occurrence or the standard ablation time (12 min) was taken as the sign for the termination of the RFA procedure. RESULTS Four different maximum voltages without the roll-off occurrence were found for the four different sizes of target tissues (dxy = 20, 25, 30 and 35 mm), and they were 36.6, 35.4, 33.9 and 32.5 V, respectively. The target tissues with diameters of 20, 25 mm can be cleanly ablated at their own maximum voltages applied (MVA) but the same finding was not found for the 35-mm target tissue. For the target tissue with diameter of 30 mm, the 50 °C isothermal contour (IT50) result showed that the target tissue can be cleanly ablated, but the same result did not show in the Arrhenius damage model result. Furthermore, two optimal RFA protocols with a minimal thermal damage to the healthy tissues were found for the target tissues with diameters of 20 and 25 mm, respectively. CONCLUSIONS The study suggests that target tissues of different sizes should be treated with different RFA protocols. The maximum target tissue volume was achieved with the MVA without the roll-off occurrence for each target tissue size when a constant RF power supply was used.
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Affiliation(s)
- Bing Zhang
- Complex and Intelligent Systems Centre, School of Mechanical and Power Engineering, East China University Science and Technology , Shanghai , China
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