Analysis of spectral shape of the optical properties of heart tissue in connection with myocardial RF ablation therapy in the visible and NIR region

2002 ◽  
Author(s):  
Johannes Swartling ◽  
Sara Palsson ◽  
Stefan Andersson-Engels
Keyword(s):  
Optical Properties ◽  
Heart Tissue ◽  
Spectral Shape ◽  
Rf Ablation ◽  
Ablation Therapy

Performance Assessment of Probe for Radio-Frequency Ablation

Volume 4 ◽  
2004 ◽  
Author(s):  
Ashvinikumar V. Mudaliar ◽  
Elaine P. Scott
Keyword(s):  
Temperature Distribution ◽  
Radio Frequency ◽  
Tumor Tissue ◽  
Healthy Tissue ◽  
Lower Portion ◽  
Distribution Data ◽  
Thermal Dose ◽  
Rf Ablation ◽  
Ablation Therapy ◽  
Tissue Region

Radio-frequency (RF) ablation is one of the most widely used methods for the treatment of hepatic malignancies. A finite element method (FEM) analysis was employed to determine the thermal dose delivered to the tumor/tissue region. We simulated heating within a RF probe implanted in generic tumor surrounded by healthy tissue using ANSYS. The 3-D model consists of a tumor / tissue region into which the RF probe is embedded inside the tumor. One-quarter symmetry was then invoked. The blood flow was modeled using Penne’s bio-heat transfer equation with differing perfusion rates between the healthy tissue and tumor volume based on literature values. The resulting temperature distribution throughout the region was determined over time. A program was written in Visual Basic to extract the temperature distribution data in the tumor/tissue region and calculate the thermal dose throughout the region. This was done by using a time–temperature Arrhenius relationship for chemical and physical rate process. Tissue necrosis is assumed complete when a thermal dose of one hour has been achieved at 43 °C. In the present study, the geometry of the electrode had a significant effect on the size of the volume of necrosis. It was found that the lower portion of the tumor did not receive the specified thermal dose relative to the upper portion of the tumor in single setting during the RF ablation therapy. This might be due to the Ni-Ti electrode, which protruded only from the top surface of the trocar. The effectiveness of the existing probe can be improved by having one more set of electrodes protruding out from the lower curved surface of the trocar. It was found that the modified probe significantly improved heating in the lower portion of tumor/tissue area, providing more symmetry between the upper and lower portion.

Interaction between grounding pads used for RF ablation therapy and magnetic resonance imaging

2005 ◽  
Vol 18 (6) ◽  
pp. 309-315 ◽  
Author(s):  
Christina Schraml ◽  
Hansjörg Graf ◽  
Andreas Boss ◽  
Stephan Clasen ◽  
Martin Leibfritz ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Rf Ablation ◽  
Resonance Imaging ◽  
Ablation Therapy

Use of Saline Injection to Create Large Thermal Lesions During Radiofrequency Ablation Therapy: 1. Thermal Model

2001 ◽  
Author(s):  
Michael G. Curley ◽  
Patrick S. Hamilton
Keyword(s):  
Heat Transfer ◽  
Radiofrequency Ablation ◽  
Thermal Model ◽  
High Current Density ◽  
Saline Injection ◽  
High Current ◽  
Rf Ablation ◽  
Ablation Therapy ◽  
Thermal Lesions ◽  
Radiofrequency Ablation Therapy

Abstract Radiofrequency (RF) energy has been successfully used to treat tachycardia and liver cancer through hyperthermic ablation. However, this therapy is limited to treating small volumes because of the high current density near the RF electrode, which leads to excessive temperatures in this region. We have developed an RF therapy that uses saline injection into the tissue surrounding the electrode to increase heat transfer in this tissue to heat significantly larger volumes. This paper shows the results of a finite difference thermal model of this therapy. Results indicate that saline-enhanced RF ablation can treat tissue volumes that are 33 times larger than those created by RF alone.

Percutaneous Radiofrequency (RF) Ablation Therapy for Hepatocellular Carcinoma

2000 ◽  
Vol 174 (1) ◽  
pp. 264-265 ◽  
Author(s):  
Toshihito Seki ◽  
Thoru Tamai ◽  
Taiichi Nakagawa ◽  
Kyoichi Inoue
Keyword(s):  
Hepatocellular Carcinoma ◽  
Rf Ablation ◽  
Ablation Therapy

scholarly journals Assessment of myocardial viability using a minimally invasive laser Doppler flowmetry on pig model

2020 ◽  
pp. 2150001
Author(s):  
Karina Litvinova ◽  
Berthold Stegemann ◽  
Francisco Leyva
Keyword(s):  
Real Time ◽  
Animal Studies ◽  
Lesion Size ◽  
Laser Doppler ◽  
Rf Ablation ◽  
Monitoring Methods ◽  
Doppler Flowmetry ◽  
Ablation Therapy ◽  
Open Chest

Background: The intra-operative real-time assessment of tissue viability can potentially improve therapy delivery and clinical outcome in cardiovascular therapies. Cardiac ablation therapy for the treatment of supraventricular or ventricular arrhythmia continues to be done without being able to assess if the intended lesion and lesion size have been achieved. Here, we report a method for continuous measurements of cardiac muscle microcirculation to provide an instrument for real-time ablation monitoring. Methods: We performed two acute open chest animal studies to assess the ability to perform real-time monitoring of creation and size of ablation lesion using a standard RF irrigated catheter. Radiofrequency ablation and laser Doppler were applied to different endocardial areas of alive open-chest pig. Results: We performed two experiments at three different RF ablation energy setting and different ablation times. Perfusion signals before and after ablation were found extensively and distinctively different. By increasing the ablation energy and time, the perfusion signal was decreasing. Conclusion: In vivo assessing the local microcirculation during RF ablation by laser Doppler can potentially be useful to differentiate between viable and nonviable ablated beating heart in real time.

scholarly journals Changes in spectral shape of tissue optical properties in conjunction with laser-induced thermotherapy

1998 ◽  
Vol 37 (7) ◽  
pp. 1256 ◽  
Author(s):  
Annika M. K. Nilsson ◽  
Christian Sturesson ◽  
David L. Liu ◽  
Stefan Andersson-Engels
Keyword(s):  
Optical Properties ◽  
Spectral Shape ◽  
Tissue Optical Properties

Design of objective lens for 200-kV high-resolution electron microscopes

1983 ◽  
Vol 41 ◽  
pp. 314-315
Author(s):  
K. Tsuno ◽  
T. Honda ◽  
Y. Harada ◽  
M. Naruse
Keyword(s):  
Optical Properties ◽  
Computer Technology ◽  
Axial Magnetic Field ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Resolution Electron ◽  
Correction Of Astigmatism ◽  
Three Stages ◽  
Electron Microscopes ◽  
Stage 1

Developement of computer technology provides much improvements on electron microscopy, such as simulation of images, reconstruction of images and automatic controll of microscopes (auto-focussing and auto-correction of astigmatism) and design of electron microscope lenses by using a finite element method (FEM). In this investigation, procedures for simulating the optical properties of objective lenses of HREM and the characteristics of the new lens for HREM at 200 kV are described.The process for designing the objective lens is divided into three stages. Stage 1 is the process for estimating the optical properties of the lens. Firstly, calculation by FEM is made for simulating the axial magnetic field distributions Bzc of the lens. Secondly, electron ray trajectory is numerically calculated by using Bzc. And lastly, using Bzc and ray trajectory, spherical and chromatic aberration coefficients Cs and Cc are numerically calculated. Above calculations are repeated by changing the shape of lens until! to find an optimum aberration coefficients.

Optical Properties of HVEM Accelerators

1975 ◽  
Vol 33 ◽  
pp. 180-181
Author(s):  
A. Strojnik ◽  
J.W. Scholl ◽  
V. Bevc
Keyword(s):  
Optical Properties ◽  
Electron Accelerator ◽  
Systematic Investigation ◽  
Electron Source ◽  
High Brightness ◽  
The Past ◽  
Wide Range ◽  
Optical Behavior

The electron accelerator, as inserted between the electron source (injector) and the imaging column of the HVEM, is usually a strong lens and should be optimized in order to ensure high brightness over a wide range of accelerating voltages and illuminating conditions. This is especially true in the case of the STEM where the brightness directly determines the highest resolution attainable. In the past, the optical behavior of accelerators was usually determined for a particular configuration. During the development of the accelerator for the Arizona 1 MEV STEM, systematic investigation was made of the major optical properties for a variety of electrode configurations, number of stages N, accelerating voltages, 1 and 10 MEV, and a range of injection voltages ϕ0 = 1, 3, 10, 30, 100, 300 kV).

Differential polarization imaging of sickled cells

1988 ◽  
Vol 46 ◽  
pp. 62-63
Author(s):  
Marcos F. Maestre
Keyword(s):  
Optical Properties ◽  
Theoretical Approach ◽  
Polarized Light ◽  
Polarization Microscopy ◽  
Spectroscopic Techniques ◽  
Polarization Imaging ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Microscopic Scale ◽  
Chiral Structures

Recently we have developed a form of polarization microscopy that forms images using optical properties that have previously been limited to macroscopic samples. This has given us a new window into the distribution of structure on a microscopic scale. We have coined the name differential polarization microscopy to identify the images obtained that are due to certain polarization dependent effects. Differential polarization microscopy has its origins in various spectroscopic techniques that have been used to study longer range structures in solution as well as solids. The differential scattering of circularly polarized light has been shown to be dependent on the long range chiral order, both theoretically and experimentally. The same theoretical approach was used to show that images due to differential scattering of circularly polarized light will give images dependent on chiral structures. With large helices (greater than the wavelength of light) the pitch and radius of the helix could be measured directly from these images.

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