Shape-shifting thermal coagulation zone during saline-infused radiofrequency ablation: A computational study on the effects of different infusion location

2020 ◽  
Vol 184 ◽  
pp. 105289 ◽  
Author(s):  
Antony S K Kho ◽  
Ji J Foo ◽  
Ean T Ooi ◽  
Ean H Ooi
Keyword(s):  
Radiofrequency Ablation ◽  
Computational Study ◽  
Thermal Coagulation ◽  
Coagulation Zone

Abstract 430: Spectral Changes Caused by Radiofrequency Ablation of Cardiac Tissue

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Mohammed Aljishi ◽  
Huda Asfour ◽  
Tigran Chahbazian ◽  
Narine Muselimyan ◽  
Luther Swift ◽  
...  
Keyword(s):  
Radiofrequency Ablation ◽  
Visual Information ◽  
Thermal Ablation ◽  
Cardiac Tissue ◽  
Cardiac Activity ◽  
Soret Band ◽  
Quantitative Information ◽  
Thermal Coagulation ◽  
Spectral Changes ◽  
Nadh Fluorescence

Persistent atrial fibrillation is commonly treated using an endoscopic catheter to eliminate anomalous sources of cardiac activity via thermal ablation. However, the procedure lacks real-time feedback. Newly developed radiofrequency ablation (RFA) catheters include a fiberoptic bundle through which visual information of tissue conditions may be collected offering an opportunity to reveal subtle differences in tissue physiology. Currently little is known about the spectral changes caused by RFA. We hypothesized that by comparing spectral changes in various areas in the heart before and after RFA, optical signatures can be used to distinguish healthy cardiac tissue from thermally ablated tissue. Excitation emission matrices (EEM) were acquired from excised porcine hearts (300-600nm). Distinct EEMs were collected from the endocardium of the left atria, ventricle, and aorta. Additionally, the fluorescence and reflectance profiles of each tissue were altered by thermal ablation. In the ventricular muscle, a reduction in the NADH fluorescence peak (360/460nm excitation/emission maxima) was most prominent. While in the aorta, collagen and elastin fluorescence peaks fused and broadened upon ablation. Changes in atrial tissue included a drop in NADH fluorescence and an overall increase in reflectance. The latter is likely caused by thermal coagulation of heme-containing proteins such as myoglobin and a weaker absorption within the Soret band. We concluded that optical signals revealed by EEMs offer quantitative information that can be used to develop diagnostic catheters, including hyperspectral imaging protocols to discern spectral changes elicited by RFA treatment.

scholarly journals Radiofrequency ablation combined with conductive fluid-based dopants (saline normal and colloidal gold): Computer modeling and ex vivo experiments.

2020 ◽  
Author(s):  
Dora Luz Castro-Lopez ◽  
Enrique Berjano ◽  
Ricardo Romero-mendez
Keyword(s):  
Electrical Conductivity ◽  
Radiofrequency Ablation ◽  
Computer Modeling ◽  
Normal Saline ◽  
Colloidal Gold ◽  
Ex Vivo ◽  
Transverse Diameter ◽  
Cylindrical Domain ◽  
Spherical Domain ◽  
Coagulation Zone

Abstract Background: The volume of the coagulation zones created during radiofrequency ablation (RFA) is limited by the appearance of roll-off. Doping the tissue with conductive fluids, e.g. gold nanoparticles (AuNPs) could enlarge these zones by delaying roll-off. Our goal was to characterize the electrical conductivity of a substrate doped with AuNPs in a computer modeling study and ex vivo experiments to investigate their effect on coagulation zone volumes. Methods: The electrical conductivity of substrates doped with normal saline or AuNPs was assessed experimentally on agar phantoms. The computer models, built and solved on COMSOL Multiphysics, consisted of a cylindrical domain mimicking liver tissue and a spherical domain mimicking a doped zone with 2, 3 and 4 cm diameters. Ex vivo experiments were conducted on bovine liver fragments under three different conditions: 1) non-doped tissue (ND Group), 2 mL of 0.9% NaCl (NaCl Group), and 2 mL of AuNPs 0.1 wt% (AuNPs Group). Results: The theoretical analysis showed that adding normal saline or colloidal gold in concentrations lower than 10% only modifies the electrical conductivity of the doped substrate with practically no change in the thermal characteristics. The computer results showed a relationship between doped zone size and electrode length regarding the created coagulation zone. There was good agreement between the ex vivo and computational results in terms of transverse diameter of the coagulation zone.Conclusions: Both the computer and ex vivo experiments showed that doping with AuNPs can enlarge the coagulation zone, especially the transverse diameter and hence enhance sphericity.

scholarly journals Percutaneous ultrasound guided PEG-coated gold nanoparticles enhanced radiofrequency ablation in liver

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tudor Mocan ◽  
Rares Stiufiuc ◽  
Calin Popa ◽  
Iuliana Nenu ◽  
Cosmin Pestean ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Radiofrequency Ablation ◽  
Physiological Saline ◽  
Control Group ◽  
Target Tissue ◽  
Porcine Liver ◽  
Contrast Enhanced ◽  
Hematoxylin And Eosin ◽  
Coagulation Zone

AbstractTo investigate the effects of PEG-coated gold nanoparticles on ablation zone volumes following in vivo radiofrequency ablation of porcine liver. This prospective study was performed following institutional animal care and committee approval was used. Radiofrequency ablations were performed in the livers of ten Sus scrofa domesticus swines. During each ablation, 10 mL (mL) of Peg-coated gold nanoparticles at two different concentrations (0.5 mg/mL and 0.01 mg/mL) were injected through the electrode channel into the target zone. For the control group, 10 mL of physiological saline was used. Five to ten minutes after each ablation, contrast enhanced ultrasound (CEUS) was performed to evaluate the volume of the coagulation zone. On day five we performed another CEUS and the animals were sacrificed. Treated tissues were explanted for quantification of the ablation zones’ volumes. Hematoxylin and eosin (H&E) staining was also performed for histologic analysis. A total of 30 ablations were performed in the livers. The mean coagulation zone volume as measured by CEUS on day 5 after RFA was: 21.69 ± 3.39 cm3, 19.22 ± 5.77 cm3, and 8.80 ± 3.33 cm3 for N1, N2 and PS respectively. The coagulation zone volume after N1 and N2 treatments was significantly higher compared to PS treatment (p < 0.001 and p = 0.025 respectively). There was no difference between N1 and N2 treatment (p = 0.60). In our proof-of concept, pilot study we have shown for the first time that when injected directly into the target tissue during RFA, gold nanoparticles can substantially increase the coagulation zone.

scholarly journals Radiofrequency ablation combined with conductive fluid-based dopants (saline normal and colloidal gold): Computer modeling and ex vivo experiments

2020 ◽  
Author(s):  
Dora Luz Castro-Lopez ◽  
Enrique Berjano ◽  
Ricardo Romero-mendez
Keyword(s):  
Electrical Conductivity ◽  
Radiofrequency Ablation ◽  
Computer Modeling ◽  
Normal Saline ◽  
Colloidal Gold ◽  
Ex Vivo ◽  
Transverse Diameter ◽  
Cylindrical Domain ◽  
Spherical Domain ◽  
Coagulation Zone

Abstract Background: The volume of the coagulation zones created during radiofrequency ablation (RFA) is limited by the appearance of roll-off. Doping the tissue with conductive fluids, e.g. gold nanoparticles (AuNPs) could enlarge these zones by delaying roll-off. Our goal was to characterize the electrical conductivity of a substrate doped with AuNPs in a computer modeling study and ex vivo experiments to investigate their effect on coagulation zone volumes. Methods: The electrical conductivity of substrates doped with normal saline or AuNPs was assessed experimentally on agar phantoms. The computer models, built and solved on COMSOL Multiphysics, consisted of a cylindrical domain mimicking liver tissue and a spherical domain mimicking a doped zone with 2, 3 and 4 cm diameters. Ex vivo experiments were conducted on bovine liver fragments under three different conditions: 1) non-doped tissue (ND Group), 2 mL of 0.9% NaCl (NaCl Group), and 2 mL of AuNPs 0.1 wt% (AuNPs Group). Results: The theoretical analysis showed that adding normal saline or colloidal gold in concentrations lower than 10% only modifies the electrical conductivity of the doped substrate with practically no change in the thermal characteristics. The computer results showed a relationship between doped zone size and electrode length regarding the created coagulation zone. There was good agreement between the ex vivo and computational results in terms of transverse diameter of the coagulation zone.Conclusions: Both the computer and ex vivo experiments showed that doping with AuNPs can enlarge the coagulation zone, especially the transverse diameter and hence enhance sphericity.

scholarly journals Radiofrequency ablation combined with conductive fluid-based dopants (saline normal and colloidal gold): Computer modeling and ex vivo experiments.

2020 ◽  
Author(s):  
Dora Luz Castro-Lopez ◽  
Enrique Berjano ◽  
Ricardo Romero-mendez
Keyword(s):  
Electrical Conductivity ◽  
Radiofrequency Ablation ◽  
Computer Modeling ◽  
Normal Saline ◽  
Colloidal Gold ◽  
Ex Vivo ◽  
Transverse Diameter ◽  
Cylindrical Domain ◽  
Spherical Domain ◽  
Coagulation Zone

Abstract Background: The coagulation zone volume created during radiofrequency ablation (RFA) is limited by the appearance of roll-off. Doping the tissue with conductive fluids, e.g. gold nanoparticles (AuNPs) could enlarge the coagulation zones by delaying the roll-off. Our goal was to characterize the electrical conductivity of a substrate doped with AuNPs and to study by computer modeling and ex vivo experiments the effect on coagulation zone volumes.Methods: The electrical conductivity of substrates doped with normal saline or AuNPs was assessed experimentally using agar phantoms. The computer models, built and solved on COMSOL Multiphysics, consisted of a cylindrical domain mimicking liver tissue and a spherical domain mimicking a doped zone with diameters of 2, 3 and 4 cm. Ex vivo experiments were conducted on bovine liver fragments and under three different doping conditions: 1) non-doped tissue (ND Group), 2 mL of 0.9% NaCl (NaCl Group), and 2 mL of AuNPs 0.1 wt% (AuNPs Group).Results: The theoretical analysis showed that adding normal saline or colloidal gold in concentrations lower than 10% only modify the electrical conductivity of the doped substrate with practically no change of the thermal characteristics. The computer results showed a relationship between doped zone size and electrode length regarding the created coagulation zone. We observed a good agreement between ex vivo and computational results in terms of transverse diameter of the coagulation zone.Conclusions: Both computer and ex vivo experiments showed that doping with AuNPs can enlarge the coagulation zone, specially the transverse diameter, hence achieving more spherical coagulation zones.

scholarly journals Conformal coverage of liver tumors by the thermal coagulation zone in 2450-MHz microwave ablation

2019 ◽  
Vol 36 (1) ◽  
pp. 590-604 ◽  
Author(s):  
Hongjian Gao ◽  
Xiaoru Wang ◽  
Shuicai Wu ◽  
Zhuhuang Zhou ◽  
Yanping Bai ◽  
...  
Keyword(s):  
Microwave Ablation ◽  
Liver Tumors ◽  
Thermal Coagulation ◽  
Conformal Coverage ◽  
Coagulation Zone

Threshold-based prediction of the coagulation zone in sequential temperature mapping in MR-guided radiofrequency ablation of liver tumours

2011 ◽  
Vol 22 (5) ◽  
pp. 1091-1100 ◽  
Author(s):  
Hansjörg Rempp ◽  
Rüdiger Hoffmann ◽  
Jörg Roland ◽  
Alexandra Buck ◽  
Antje Kickhefel ◽  
...  
Keyword(s):  
Radiofrequency Ablation ◽  
Liver Tumours ◽  
Temperature Mapping ◽  
Coagulation Zone
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