Quantification of Thermal Injury to the Healthy Tissue Due to Imperfect Electrode Placements During Radiofrequency Ablation of Breast Tumor

Radiofrequency ablation (RFA) has emerged as an alternative treatment modality for treating various tumors with minimum intervention. The application of RFA in treating breast tumor is still in its infancy stage. Nevertheless, promising results have been obtained while treating early stage localized breast cancer with RFA procedure. The outcome of RFA is tremendously dependent on the precise insertion of the electrode into the geometric center of the tumor. However, there remains plausible chances of inaccuracies in the electrode placement that can result in slight displacement of the electrode tip from the actual desired location during temperature-controlled RFA application. The present numerical study aims at capturing the influence of inaccuracies in electrode placement on the input energy, treatment time and damage to the surrounding healthy tissue during RFA of breast tumor. A thermo-electric analysis has been performed on three-dimensional heterogeneous model of multilayer breast with an embedded early stage spherical tumor of 1.5 cm. The temperature distribution during the RFA has been obtained by solving the coupled electric field equation and Pennes bioheat transfer equation, while the ablation volume has been computed using the Arrhenius cell death model. It has been found that significant variation in the energy consumption, time required for complete tumor necrosis, and the shape of ablation volume among different positions of the electrode considered in this study are prevalent.

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Parametric evaluation of impedance curve in radiofrequency ablation: A quantitative description of the asymmetry and dynamic variation of impedance in bovine ex vivo model

PLoS ONE ◽

10.1371/journal.pone.0245145 ◽

2021 ◽

Vol 16 (1) ◽

pp. e0245145

Author(s):

Ronei Delfino da Fonseca ◽

Paulo Roberto Santos ◽

Melissa Silva Monteiro ◽

Luciana Alves Fernandes ◽

Andreia Henrique Campos ◽

...

Keyword(s):

Radiofrequency Ablation ◽

Liver Tumors ◽

Ex Vivo ◽

Early Stage ◽

Quantitative Description ◽

Maximum Point ◽

Performance Indices ◽

Ex Vivo Model ◽

Ablation Volume ◽

Impedance Curve

Radiofrequency ablation (RFA) is a treatment for liver tumors with advantages over the traditional treatment of surgical resection. This procedure has the shortest recovery time in early stage tumors. The objective of this study is to parameterize the impedance curve of the RFA procedure in an ex vivo model by defining seven parameters (t1/2, tminimum, tend, Zinitial, Z1/2, Zminimum and Zend). Based on these parameters, three performance indices are defined: one to identify the magnitude of impedance curve asymmetry (δ), one Drop ratio (DR) describing the percentage of impedance decrease until the minimum impedance point is reached, and Ascent Ratio (AR) describing the magnitude of increase in impedance from the minimum impedance point to its maximum point. Fifty ablations were performed in a bovine ex vivo model to measure and evaluate the proposed parameters and performance index. The results show that the groups had an average δ of 29.02%, DR of 22.41%, and AR of 545.33% for RFA without the use of saline or deionized solutions. The saline solution and deionized water-cooled groups indicated the correlation of performance indices δ, DR, and AR with the obtained final ablation volume. Therefore, by controlling these parameters and indices, lower recurrence is achieved.

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THERMAL CHARACTERIZATION USING FOURIER AND NON-FOURIER CONDUCTION DURING RADIOFREQUENCY ABLATION OF BREAST TUMOR

Proceeding of Proceedings of CHT-17 ICHMT International Symposium on Advances in Computational Heat Transfer May 28-June 1, 2017, Napoli, Italy ◽

10.1615/ichmt.2017.cht-7.190 ◽

2017 ◽

Author(s):

Sundeep Singh ◽

Ramjee Repaka

Keyword(s):

Radiofrequency Ablation ◽

Breast Tumor ◽

Thermal Characterization

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Perivascular vital cells in the ablation center after multibipolar radiofrequency ablation in an in vivo porcine model

Scientific Reports ◽

10.1038/s41598-021-93406-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

F. G. M. Poch ◽

C. A. Neizert ◽

B. Geyer ◽

O. Gemeinhardt ◽

S. M. Niehues ◽

...

Keyword(s):

Radiofrequency Ablation ◽

Early Stage ◽

Pringle Maneuver ◽

Vessel Diameter ◽

Inflow Occlusion ◽

White Zone ◽

Cell Vitality ◽

Internally Cooled ◽

Hepatic Vessels

AbstractMultibipolar radiofrequency ablation (RFA) is an advanced ablation technique for early stage hepatocellular carcinoma and liver metastases. Vessel cooling in multibipolar RFA has not been systematically investigated. The objective of this study was to evaluate the presence of perivascular vital cells within the ablation zone after multibipolar RFA. Multibipolar RFA were performed in domestic pigs in vivo. Three internally cooled bipolar RFA applicators were used simultaneously. Three experimental settings were planned: (1) inter-applicator-distance: 15 mm; (2) inter-applicator-distance: 20 mm; (3) inter-applicator-distance: 20 mm with hepatic inflow occlusion (Pringle maneuver). A vitality staining was used to analyze liver cell vitality around all vessels in the ablation center with a diameter > 0.5 mm histologically. 771 vessels were identified. No vital tissue was seen around 423 out of 429 vessels (98.6%) situated within the central white zone. Vital cells could be observed around major hepatic vessels situated adjacent to the ablation center. Vessel diameter (> 3.0 mm; p < 0.05) and low vessel-to-ablation-center distance (< 0.2 mm; p < 0.05) were identified as risk factors for incomplete ablation adjacent to hepatic vessels. The vast majority of vessels, which were localized in the clinically relevant white zone, showed no vital perivascular cells, regardless of vessel diameter and vessel type. However, there was a risk of incomplete ablation around major hepatic vessels situated directly within the ablation center. A Pringle maneuver could avoid incomplete ablations.

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Optical signatures of radiofrequency ablation in biological tissues

Scientific Reports ◽

10.1038/s41598-021-85653-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Pranav Lanka ◽

Kalloor Joseph Francis ◽

Hindrik Kruit ◽

Andrea Farina ◽

Rinaldo Cubeddu ◽

...

Keyword(s):

Radiofrequency Ablation ◽

Treatment Time ◽

Ex Vivo ◽

Biological Tissues ◽

Tissue Response ◽

Optical Monitoring ◽

Diffuse Optical Spectroscopy ◽

Spectral Changes ◽

Scattering Spectra ◽

Optical Behavior

AbstractAccurate monitoring of treatment is crucial in minimally-invasive radiofrequency ablation in oncology and cardiovascular disease. We investigated alterations in optical properties of ex-vivo bovine tissues of the liver, heart, muscle, and brain, undergoing the treatment. Time-domain diffuse optical spectroscopy was used, which enabled us to disentangle and quantify absorption and reduced scattering spectra. In addition to the well-known global (1) decrease in absorption, and (2) increase in reduced scattering, we uncovered new features based on sensitive detection of spectral changes. These absorption spectrum features are: (3) emergence of a peak around 840 nm, (4) redshift of the 760 nm deoxyhemoglobin peak, and (5) blueshift of the 970 nm water peak. Treatment temperatures above 100 °C led to (6) increased absorption at shorter wavelengths, and (7) further decrease in reduced scattering. This optical behavior provides new insights into tissue response to thermal treatment and sets the stage for optical monitoring of radiofrequency ablation.

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Early Detection and Dynamic Changes of Circulating Tumor Cells in Transgenic NeuN Transgenic (NTTg) Mice with Spontaneous Breast Tumor Development

Cancers ◽

10.3390/cancers13133294 ◽

2021 ◽

Vol 13 (13) ◽

pp. 3294

Author(s):

Wen-Sy Tsai ◽

Tsung-Fu Hung ◽

Jia-Yang Chen ◽

Shu-Huan Huang ◽

Ying-Chih Chang

Keyword(s):

Tumor Cells ◽

Circulating Tumor Cells ◽

Breast Tumor ◽

Early Stage ◽

Tumor Development ◽

P Value ◽

Vascular Density ◽

Dynamic Changes ◽

Tumor Bearing ◽

Development Methods

Background: This study used NeuN transgenic (NTTg) mice with spontaneous breast tumor development to evaluate the dynamic changes of circulating tumor cells (CTCs) prior to and during tumor development. Methods: In this longitudinal, clinically uninterrupted study, we collected 75 μL of peripheral blood at the age of 8, 12, 16, and 20 weeks in the first group of five mice, and at the age of 32 weeks, the time of tumor palpability, and one week after tumor palpability in the second group of four mice. Diluted blood samples were run through a modified mouse-CMx chip to isolate the CTCs. Results: The CTC counts of the first group of mice were low (1 ± 1.6) initially. The average CTC counts were 16 ± 9.5, 29.0 ± 18.2, and 70.0 ± 30.3 cells per 75 μL blood at the age of 32 weeks, the time of tumor palpability, and one week after tumor palpability, respectively. There was a significant positive correlation between an increase in CTC levels and tumor vascular density (p-value < 0.01). This correlation was stronger than that between CTC levels and tumor size (p-value = 0.076). The captured CTCs were implanted into a non-tumor-bearing NTTg mouse for xenografting, confirming their viability and tumorigenesis. Conclusion: Serial CTCs during an early stage of tumor progression were quantified and found to be positively correlated with the later tumor vascular density and size. Furthermore, the successful generation of CTC-derived xenografts indicates the tumorigenicity of this early onset CTC population.

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Retrospective analysis of Ca cervix postoperative: An institutional study

10.1055/s-0039-1685282 ◽

2016 ◽

Author(s):

Chandra Prakash

Keyword(s):

Squamous Cell Carcinoma ◽

Cell Carcinoma ◽

Squamous Cell ◽

Treatment Time ◽

Residual Disease ◽

Early Stage ◽

Treatment Length ◽

Recommended Treatment ◽

Carcinoma Of Cervix ◽

Well Differentiated

Introduction: Carcinoma of cervix is one of the leading causes of death worldwide and in developing countries like India. Cervical cancer is third most common cancer among women however there is a good chance of curability if diagnosed in early stage. Materials and Methods: We had analysed 78 patient of carcinoma of cervix post op who were registered from 2012 to 2015 at Dr. Ram Manohar Lohia Institute of Medical Sciences. Results: We analysed 78 patients between age of 32-70 years and median age is 50 year. Among all patients squamous cell carcinoma is most common (65 patient), adenocarcinoma were 12 and lieomyosarcoma was 1 patient. Among all patient 12 were of adenocarcinoma, 1 of lieomyosarcoma and 65 patient of squamous cell carcinoma. On examination 55 patients were NAD and 23 were residual. Among squamous cell carcinoma 35 were moderate differentiated, 18 were well differentiated and 12 were of poorly differentiated. On examination 55 patients were NAD rest were having disease. Gap between EBRT and SORBO ranging from 3 to 99 days and median is 27 days and median is 29 days. Treatment length varies from 4 cm to 8 cm and median is 6 cm. Ovoide size ranges from 2.5 cm to 3.5 cm and median is 2.5 cm. Dose per fraction ranges from 5 Gy to 9 Gy and median was 9 Gy. Median fraction of session were 2. Out of 78 patients 2 were developed metastasis and 6 having residual disease. 28 patients were NAD and rest were referral and send back to parent hospital. Conclusion: Due to lack of resources and awareness of disease maximum number of patient presented with advanced stage. The recommended treatment time could not be achieved due to scarcity of cancer centres, treatment time is prolonged. We have not found any relation between treatment length and outcome. We are still investigating to conclude to found out relation among these variables.

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