Radiofrequency Energy and Electrode Proximity Influences Stereoelectroencephalography-Guided Radiofrequency Thermocoagulation Lesion Size: An In Vitro Study with Clinical Correlation

2018 ◽  
Vol 15 (4) ◽  
pp. 461-469 ◽  
Author(s):  
Michael D Staudt ◽  
Sarita Maturu ◽  
Jonathan P Miller
Keyword(s):  
Focal Epilepsy ◽  
Intractable Epilepsy ◽  
High Energy ◽  
Lesion Size ◽  
Magnetic Resonance Images ◽  
Low Energy ◽  
Radiofrequency Energy ◽  
Radiofrequency Thermocoagulation ◽  
Radiofrequency Lesions

Abstract BACKGROUND Radiofrequency thermocoagulation of epileptogenic foci via stereoelectroencephalography (SEEG) electrodes has been suggested as a treatment for medically intractable epilepsy, but reported outcomes have been suboptimal, possibly because lesions generated using conventional high-energy radiofrequency parameters are relatively small. OBJECTIVE To describe a technique of delivering low energy across separate SEEG electrodes in order to create large confluent radiofrequency lesions. METHODS The size and configuration of radiofrequency lesions using different radiofrequency intensity and interelectrode distance was assessed in egg whites. Magnetic resonance images (MRI) from 3 patients who had undergone radiofrequency lesion creation were evaluated to determine the contribution of lesion intensity and electrode separation on lesion size. Electroencephalography, MRI, and clinical data were assessed before and after lesion creation. RESULTS Both in Vitro and in Vivo analysis revealed that less energy paradoxically produced larger lesions, with the largest possible lesions produced when radiofrequency power was applied for long duration at less than 3 W. Linear separation of electrodes also contributed to lesion size, with largest lesions produced when electrodes were separated by a linear distance of between 5 and 12 mm. Clinical lesions produced using these parameters were large and resulted in improvement in interictal and ictal activity. CONCLUSION Radiofrequency lesions produced using low-energy delivery between SEEG electrodes in close proximity can produce a large lesion. These findings might have advantages for treatment of focal epilepsy.

scholarly journals Analysis of Radiofrequency Lesions in Egg Whites in Vitro Produced by Application of the Tew Electrode for Different Temperatures and Times

2015 ◽  
Vol 20 (6) ◽  
pp. 316-320 ◽  
Author(s):  
Young Suk Kwon ◽  
So Young Lim ◽  
Jong Ho Kim ◽  
Ji Su Jang ◽  
Chul Ho Kim ◽  
...  
Keyword(s):  
Distal Radius ◽  
Mixed Model ◽  
Glass Container ◽  
Lesion Size ◽  
External Radius ◽  
Internal Radius ◽  
S 100 ◽  
Different Temperatures ◽  
Radiofrequency Lesions

BACKGROUND: Understanding the size and shape of radiofrequency lesions is important to reduce side effects when applied to patients.OBJECTIVES: To investigate the radiofrequency lesions produced by the application of the Tew electrode for different temperatures and times.METHODS: The white from a fresh hen’s egg was placed in a rectangular glass container and warmed to 37°C. After immersion of the Tew electrode in the egg white, radiofrequency lesions were produced at 65°C, 70°C, 75°C, 80°C, 85°C and 90°C. For each temperature, photographs were taken at 10 s, 20 s, 30 s, 40 s, 50 s, 60 s, 70 s, 80 s, 90 s, 100 s, 110 s and 120 s. The size of the lesion was measured at each temperature and time. A mixed model was used to analyze the data.RESULTS: The size of the lesion increased with increasing temperature and time. There were statistically significant differences in the size of the internal radius between the 65°C and 70°C groups and the 70°C and 75°C groups, as well as in the 70°C and 75°C groups in the size of the external radius and the 60°C to 80°C groups in the size of the distal radius. The maximum lesion size was produced at 90°C and 120 s, and was 1.06±0.16 mm in internal radius, 0.37±0.15 mm in external radius, 0.39±0.04 mm in distal radius.CONCLUSION: The Tew electrode produces lesions following the contour of the tip, and the internal radius is larger than the external and distal radius. The best combination of temperature and time for lesioning using the Tew electrode is 80°C, for 60 s to 90 s.

scholarly journals Value of stereoelectroencephalography (SEEG)-guided radiofrequency thermocoagulation in treating drug-resistant focal epilepsy

2019 ◽  
Vol 5 (3) ◽  
pp. 189-202
Author(s):  
Jianjun Bai ◽  
Wenjing Zhou ◽  
Haixiang Wang ◽  
Bingqing Zhang ◽  
Jiuluan Lin ◽  
...  
Keyword(s):  
Refractory Epilepsy ◽  
Focal Epilepsy ◽  
Intractable Epilepsy ◽  
Epileptogenic Zone ◽  
Presurgical Evaluation ◽  
The Past ◽  
Limited Efficacy ◽  
Radiofrequency Thermocoagulation ◽  
Temporary Treatment ◽  
Promising Treatment

Stereoelectroencephalography (SEEG) has been widely used in the presurgical evaluation of patients with medically intractable epilepsy. In the past, SEEG was commonly used as a method for mapping and localizing the epileptogenic zone (EZ). Since 2004, several studies have been conducted to examine the effectiveness of SEEG-guided radiofrequency thermocoagulation (RF-TC) in treating refractory epilepsy. However, the seizure-free and responder rates varied greatly across studies. We aimed to analyze the outcome of 56 patients who were treated with SEEG-guided RF-TC to evaluate the effectiveness of this treatment. SEEG-guided RF-TC can be considered as a treatment for refractory epilepsy. However, due to its limited efficacy, SEEG-guided RF-TC might be regarded as a temporary treatment performed under SEEG rather than a promising treatment for refractory epilepsy.

scholarly journals Role of bacteriophage T4 baseplate in regulating assembly and infection

2016 ◽  
Vol 113 (10) ◽  
pp. 2654-2659 ◽  
Author(s):  
Moh Lan Yap ◽  
Thomas Klose ◽  
Fumio Arisaka ◽  
Jeffrey A. Speir ◽  
David Veesler ◽  
...  
Keyword(s):  
Bacteriophage T4 ◽  
Energy Landscape ◽  
Structural Data ◽  
High Energy ◽  
Low Energy ◽  
Energy Structure ◽  
Host Bacterium ◽  
Energy Star

Bacteriophage T4 consists of a head for protecting its genome and a sheathed tail for inserting its genome into a host. The tail terminates with a multiprotein baseplate that changes its conformation from a “high-energy” dome-shaped to a “low-energy” star-shaped structure during infection. Although these two structures represent different minima in the total energy landscape of the baseplate assembly, as the dome-shaped structure readily changes to the star-shaped structure when the virus infects a host bacterium, the dome-shaped structure must have more energy than the star-shaped structure. Here we describe the electron microscopy structure of a 3.3-MDa in vitro-assembled star-shaped baseplate with a resolution of 3.8 Å. This structure, together with other genetic and structural data, shows why the high-energy baseplate is formed in the presence of the central hub and how the baseplate changes to the low-energy structure, via two steps during infection. Thus, the presence of the central hub is required to initiate the assembly of metastable, high-energy structures. If the high-energy structure is formed and stabilized faster than the low-energy structure, there will be insufficient components to assemble the low-energy structure.

Deep Brain Stimulator Electrodes Used for Lesioning: Proof of Principle

Neurosurgery ◽  
2001 ◽  
Vol 49 (2) ◽  
pp. 363-369 ◽  
Author(s):  
Michael Y. Oh ◽  
Mojgan Hodaie ◽  
Seong Ho Kim ◽  
Ahmed Alkhani ◽  
Anthony E. Lang ◽  
...  
Keyword(s):  
Subthalamic Nucleus ◽  
Lesion Size ◽  
Therapeutic Benefit ◽  
Ethical Review ◽  
Deep Brain Stimulator ◽  
Implanted Electrodes ◽  
Radiofrequency Lesions ◽  
The Right ◽  
Deep Brain

Abstract OBJECTIVE Patients with chronically implanted deep brain stimulator (DBS) electrodes can encounter complications requiring hardware removal. We assessed the safety and efficacy of using implanted DBS electrodes to create a therapeutic lesion before their removal. METHODS Revision or removal of the DBS electrodes was required in two patients who had previously undergone DBS implantation. We conducted a series of in vitro experiments to confirm that the DBS electrodes could be used to generate radiofrequency lesions and to assess the relationship between radiofrequency parameters and lesion size. With this information, and with the approval of the hospital ethical review board, implanted electrodes were used to create incremental radiofrequency lesions in the thalamus in one patient and in the subthalamic nucleus in another. The procedures were performed under local anesthesia with contiguous contacts of the DBS lead connected to the active and reference sites of the RF generator to create a bipolar lesion. RESULTS A 51-year-old man with essential tremor and a thalamic DBS required repeated battery changes secondary to tolerance and high voltage demands. Rather than replacing the battery, a radiofrequency thalamotomy was performed by using the existing left DBS electrode. At the 6-month follow-up examination, successful lesioning provided near complete tremor control. A second patient, a 50-year-old man with Parkinson's disease who had undergone bilateral subthalamic deep brain stimulation, developed skin erosion over the DBS hardware. A subthalamic nucleus lesion was made through the right DBS electrode. Lesion position and size were confirmed with magnetic resonance imaging. CONCLUSION Lesions can be made through chronically implanted DBS electrodes in a safe, graded fashion and can produce therapeutic benefit.

scholarly journals Nanoemulsions containing Garcinia mangostana L. pericarp extract for topical applications: Development, characterization, and in vitro percutaneous penetration assay

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261792
Author(s):  
Elsa Anisa Krisanti ◽  
Dyah Paramawidya Kirana ◽  
Kamarza Mulia
Keyword(s):  
Xanthan Gum ◽  
Droplet Diameter ◽  
Coconut Oil ◽  
High Energy ◽  
Low Energy ◽  
Percutaneous Penetration ◽  
Virgin Coconut Oil ◽  
Garcinia Mangostana ◽  
Topical Applications

A highly stable oil-in-water nanoemulsion for topical applications, containing mangostins extracted from the pericarp of mangosteen (Garcinia mangostana L.), is a promising strategy to protect mangostins as well as to improve penetration of these important antioxidants through the skins. Nanoemulsions consisted of virgin coconut oil as the oil phase, Tween-80 and Span-80 as surfactants, and xanthan gum as the thickening agent, were prepared using the high-energy and low-energy emulsification methods. The nanoemulsions that were stable up to 28 days had oil droplet diameter of 220 nm to 353 nm and zeta potential of -46.9 mV to -63.7 mV. The accelerated stability test showed that the most stable nanoemulsions were those prepared using the low-energy emulsification method with an estimated shelf life of eleven months, composed of 11% oil phase, 17% surfactant, and 72% aqueous phase. The in vitro percutaneous penetration test for the nanoemulsion with added xanthan gum provided high cumulative skin penetration of mangostins of up to 114 μg/cm2. The results of this study indicate that virgin coconut oil-based nanoemulsions containing mangostins, prepared using the low-energy emulsification method, stabilized by xanthan gum and mixed at 40°C can prospectively be used for topical applications.

Impact of power and contact force in ablation-index guided radiofrequency lesions in an in vitro model

EP Europace ◽  
2021 ◽  
Vol 23 (Supplement_3) ◽  
Author(s):  
C Lozano-Granero ◽  
E Franco Diez ◽  
R Matia Frances ◽  
A Hernandez-Madrid ◽  
I Sanchez Perez ◽  
...  
Keyword(s):  
Contact Force ◽  
Lesion Size ◽  
Public Institution ◽  
Lesion Volume ◽  
Lesion Depth ◽  
Lower Index ◽  
Ablation Index ◽  
Radiofrequency Lesions ◽  
Size And Morphology

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Electrophisiology Section of the Spanish Society of Cardiology Introduction. Lesion Size Index (LSI) and Ablation Index (AI) are markers of lesion quality that incorporate power, contact force (CF), and time in a weighted formula to estimate lesion size. Although accurate predicting lesion depth in-vitro, their precision in lesion size estimation has not been well established for certain power and CF settings. Purpose. We conducted an experimental ex-vivo study to analyse the effect of power and CF in size and morphology of ablation lesions in a porcine heart model. Methods. 24 sets of 10 perpendicular epicardial radiofrequency applications were performed with two commercially available catheters (TactiCath, Sensor Enabled; and SmartTouch) on porcine left ventricle submerged in 37ºC saline, combining different power (25, 30, 35, 40, 50 and 60W) and CF (10 and 20g) settings, and aiming at a lower (LSI/AI of 5/400) or higher (LSI/AI of 6/550) index. After each application, lesions were cross-sectioned and measured. Results. 480 lesions were performed. For a given target index and CF, significant differences in lesion volume and depth with different power settings were observed with both catheters. Regarding lesion volume, statistically significant differences were observed with all CF and LSI targets with TactiCath, except for 10 g and LSI 5 (10 g and LSI 5, p = 0.4134; 10 g and LSI 6, p < 0.0001; 20 g and LSI 5, p < 0.0001; 20 g and LSI 6, p < 0.0001). The same occurred for SmartTouch, showing statistically significant differences with all CF and AI targets, except for 20 g and AI 550 (10 g and AI 400, p = 0.0001; 10 g and AI 550, p < 0.0001; 20 g and AI 400, p < 0.0001; 20 g and AI 550, p = 0.001). Similar differences could be found in lesion depth with each catheter. Globally, lesions performed with 50 and 60W were significantly smaller and shallower than those performed with 35 or 40W (figure). Regarding CF, catheters behaved differently: lesions performed with 10g were smaller and shallower than those performed with 20g with Tacticath, while being bigger and deeper with SmartTouch. In a side-by-side comparison, lesions performed with TactiCath were smaller and shallower than those performed with SmartTouch when applying a lower CF of 10g, both when targeting a lower index objective (volume: 41.8 ± 54.3mm3 vs 158.3 ± 33.2mm3, p < 0.0001; depth: 2 ± 1.7mm vs 4.6 ± 0.5mm, p < 0.0001) or a higher index objective (volume: 103.1 ± 56.5mm3 vs 280 ± 54mm3, p < 0.0001; depth: 4 ± 1.1mm vs 5.8 ± 0.5mm, p < 0.0001). However, lesions with TactiCath were bigger and deeper when applying a higher CF of 20g aiming at a lower index objective (volume: 123.8 ± 39.9mm3 vs 89.7 ± 29.4mm3, p < 0.0001; depth: 4 ± 0.8mm3 vs 3.6 ± 0.5mm, p < 0.0001). No statistically significant difference was observed when applying a higher CF of 20g aiming at a higher index objective. Conclusions. Size and morphology of index-guided radiofrequency lesions varied significantly with different power and CF settings, highlighting the importance of achieving a good CF in any ablation procedure. Abstract Figure. Box-plot of lesion volume

scholarly journals Efficacy of Removal of Sucrose-Supplemented Interproximal Plaque by Electric Toothbrushes in an In Vitro Model

2005 ◽  
Vol 71 (2) ◽  
pp. 1114-1116 ◽  
Author(s):  
C. K. Hope ◽  
A. Petrie ◽  
M. Wilson
Keyword(s):  
In Vitro Model ◽  
High Energy ◽  
Low Energy ◽  
Fluid Shear ◽  
Shear Forces ◽  
Plaque Removal ◽  
Plaque Development ◽  
Viable Bacteria ◽  
Vitro Model

ABSTRACT Electric toothbrushes were evaluated using a model of plaque removal by fluid shear forces. Sucrose supplementation during plaque development did not affect the removal of bacteria from biofilm exposed to low-energy shear but did increase their resistance to high-energy shear. The toothbrush supplying high-energy shear forces removed significantly more viable bacteria.

Low energy vs. high energy depositional settings and related sedimentary bodies in early Senenian rudist bearing carbonate shelves (central-southern Italy)

2001 ◽  
Vol 28 (1) ◽  
pp. 37-40 ◽  
Author(s):  
Gabriele Carannante ◽  
A. Laviano ◽  
D. Ruberti ◽  
Lucia Simone ◽  
G. Sirna ◽  
...  
Keyword(s):  
Southern Italy ◽  
High Energy ◽  
Low Energy ◽  
Depositional Settings

Preincubation with Sn-complexes causes intensive intracellular retention of 99mTc in thyroid cells in vitro

2012 ◽  
Vol 51 (05) ◽  
pp. 179-185 ◽  
Author(s):  
M. Wendisch ◽  
D. Aurich ◽  
R. Runge ◽  
R. Freudenberg ◽  
J. Kotzerke ◽  
...  
Keyword(s):  
Cell Model ◽  
Low Energy ◽  
Thyroid Cells ◽  
Low Energy Electrons ◽  
A Cell ◽  
Vitro Model ◽  
Uptake Studies ◽  
Radiobiological Effects ◽  
Radioactivity Retention

SummaryTechnetium radiopharmaceuticals are well established in nuclear medicine. Besides its well-known gamma radiation, 99mTc emits an average of five Auger and internal conversion electrons per decay. The biological toxicity of these low-energy, high-LET (linear energy transfer) emissions is a controversial subject. One aim of this study was to estimate in a cell model how much 99mTc can be present in exposed cells and which radiobiological effects could be estimated in 99mTc-overloaded cells. Methods: Sodium iodine symporter (NIS)- positive thyroid cells were used. 99mTc-uptake studies were performed after preincubation with a non-radioactive (cold) stannous pyro - phosphate kit solution or as a standard 99mTc pyrophosphate kit preparation or with pure pertechnetate solution. Survival curves were analyzed from colony-forming assays. Results: Preincubation with stannous complexes causes irreversible intracellular radioactivity retention of 99mTc and is followed by further pertechnetate influx to an unexpectedly high 99mTc level. The uptake of 99mTc pertechnetate in NIS-positive cells can be modified using stannous pyrophosphate from 3–5% to >80%. The maximum possible cellular uptake of 99mTc was 90 Bq/cell. Compared with nearly pure extracellular irradiation from routine 99mTc complexes, cell survival was reduced by 3–4 orders of magnitude after preincubation with stannous pyrophosphate. Conclusions: Intra cellular 99mTc retention is related to reduced survival, which is most likely mediated by the emission of low-energy electrons. Our findings show that the described experiments constitute a simple and useful in vitro model for radiobiological investigations in a cell model.

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