scholarly journals Thermal Evaluation of a Micro-Coaxial Antenna Set to Treat Bone Tumors: Design, Parametric FEM Modeling and Evaluation in Multilayer Phantom and Ex Vivo Porcine Tissue

Electronics ◽  
2021 ◽  
Vol 10 (18) ◽  
pp. 2289
Author(s):  
Texar Javier Ramírez-Guzmán ◽  
Citlalli Jessica Trujillo-Romero ◽  
Raquel Martínez-Valdez ◽  
Lorenzo Leija-Salas ◽  
Arturo Vera-Hernández ◽  
...  
Keyword(s):  
Standing Wave ◽  
Power Loss ◽  
Bone Tumors ◽  
Ex Vivo ◽  
Bone Cancer ◽  
Biological Tissues ◽  
Fem Modeling ◽  
Insertion Depth ◽  
Porcine Tissue ◽  
Metal Tip

Bone cancer is rare in adults, the most affected persons by this disease are young people and children. The common treatments for bone cancer are surgery, chemotherapy, and targeted therapies; however, all of them have side-effects that decrease the patient’s quality of life. Thermotherapy is one of the most promising treatments for bone cancer; its main goal is to increase the tumor temperature to kill cancerous cells. Although some micro-coaxial antennas have been used to treat bone tumors, most of them are designed to treat soft tissue. Therefore, the purpose of this work is to analyze the thermal behavior of four micro-coaxial antennas specifically designed to generate thermal ablation in bone tissue to treat bone tumors, at 2.45 GHz. The proposed antennas were the metal-tip monopole (MTM), the choked metal-tip monopole (CMTM), the double slot (DS) and the choked double slot (CDS). The design and optimization of the antennas by using the Finite Element Method (FEM) allow to predict the optimal antenna dimensions and their performance when they are in contact with the affected biological tissues (bone, muscle, and fat). In the FEM model, a maximum power transmission was selected as the main parameter to choose the optimum antenna design, i.e., a Standing Wave Ratio (SWR) value around 1.2–1.5. The four optimized antennas were constructed and experimentally evaluated. The evaluation was carried out in multilayer phantoms (fat, muscle, cortical, and cancellous bone) and ex vivo porcine tissue at different insertion depths of the antennas. To fully evaluate the antennas performance, the standing wave ratio (SWR), power loss, temperature profiles, and thermal distributions were analyzed. In the experimentation, the four antennas were able to reach ablation temperatures (>60 °C) and the highest reached SWR was 1.7; the MTM (power loss around 16%) and the CDS (power loss around 6.4%) antennas presented the lowest SWR values depending on the antenna insertion depth, either in multilayer tissue phantom or in ex vivo tissue. These proposed antennas allow to obtain ablation temperatures with an input power of 5 W after 5 min of treatment; these values are lower than the ones reported in the literature.

scholarly journals Numerical Sensitivity Analysis for Dielectric Characterization of Biological Samples by Open-Ended Probe Technique

Sensors ◽  
2020 ◽  
Vol 20 (13) ◽  
pp. 3756
Author(s):  
Marta Cavagnaro ◽  
Giuseppe Ruvio
Keyword(s):  
Water Content ◽  
Ex Vivo ◽  
High Water ◽  
Biological Tissues ◽  
Fundamental Aspect ◽  
High Water Content ◽  
Insertion Depth ◽  
Dielectric Characterization

Dielectric characterization of biological tissues has become a fundamental aspect of the design of medical treatments based on electromagnetic energy delivery and their pre-treatment planning. Among several measuring techniques proposed in the literature, broadband and minimally-invasive open-ended probe measurements are best-suited for biological tissues. However, several challenges related to measurement accuracy arise when dealing with biological tissues in both ex vivo and in vivo scenarios such as very constrained set-ups in terms of limited sample size and probe positioning. By means of the Finite Integration Technique in the CST Studio Suite® software, the numerical accuracy of the reconstruction of the complex permittivity of a high water-content tissue such as liver and a low water-content tissue such as fat is evaluated for different sample dimensions, different location of the probe, and considering the influence of the background environment. It is found that for high water-content tissues, the insertion depth of the probe into the sample is the most critical parameter on the accuracy of the reconstruction. Whereas when low water-content tissues are measured, the probe could be simply placed in contact with the surface of the sample but a deeper and wider sample is required to mitigate biasing effects from the background environment. The numerical analysis proves to be a valid tool to assess the suitability of a measurement set-up for a target accuracy threshold.

scholarly journals Optical signatures of radiofrequency ablation in biological tissues

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.

scholarly journals Applications of Vibrational Spectroscopy for Analysis of Connective Tissues

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 922
Author(s):  
William Querido ◽  
Shital Kandel ◽  
Nancy Pleshko
Keyword(s):  
Raman Spectroscopy ◽  
Vibrational Spectroscopy ◽  
Near Infrared ◽  
Ex Vivo ◽  
Biological Tissues ◽  
Label Free ◽  
Connective Tissues ◽  
Bone Properties ◽  
Composition And Structure

Advances in vibrational spectroscopy have propelled new insights into the molecular composition and structure of biological tissues. In this review, we discuss common modalities and techniques of vibrational spectroscopy, and present key examples to illustrate how they have been applied to enrich the assessment of connective tissues. In particular, we focus on applications of Fourier transform infrared (FTIR), near infrared (NIR) and Raman spectroscopy to assess cartilage and bone properties. We present strengths and limitations of each approach and discuss how the combination of spectrometers with microscopes (hyperspectral imaging) and fiber optic probes have greatly advanced their biomedical applications. We show how these modalities may be used to evaluate virtually any type of sample (ex vivo, in situ or in vivo) and how “spectral fingerprints” can be interpreted to quantify outcomes related to tissue composition and quality. We highlight the unparalleled advantage of vibrational spectroscopy as a label-free and often nondestructive approach to assess properties of the extracellular matrix (ECM) associated with normal, developing, aging, pathological and treated tissues. We believe this review will assist readers not only in better understanding applications of FTIR, NIR and Raman spectroscopy, but also in implementing these approaches for their own research projects.

A robust ex vivo method to evaluate the diffusion properties of agents in biological tissues

2019 ◽  
Vol 12 (4) ◽  
pp. e201800333 ◽  
Author(s):  
Isa Carneiro ◽  
Sónia Carvalho ◽  
Rui Henrique ◽  
Luís M. Oliveira ◽  
Valery V. Tuchin
Keyword(s):  
Ex Vivo ◽  
Biological Tissues ◽  
Diffusion Properties

A study of the dielectric properties of biological tissues: Ex-vivo vs preserved samples

2017 ◽  
Author(s):  
Irina L. Alborova ◽  
Julian Bonello ◽  
Lourdes Farrugia ◽  
Charles V. Sammut ◽  
Lesya N. Anishchenko
Keyword(s):  
Dielectric Properties ◽  
Ex Vivo ◽  
Biological Tissues

Intraocular Pressure Estimation Method Based on Vibration Propagation Characteristics According to Structure Contact

2021 ◽  
Vol 263 (1) ◽  
pp. 5552-5554
Author(s):  
Kim Deukha ◽  
Seongwook Jeon ◽  
Won June Lee ◽  
Junhong Park
Keyword(s):  
Intraocular Pressure ◽  
Short Term Memory ◽  
Learning Algorithm ◽  
Ex Vivo ◽  
Estimation Method ◽  
Biological Tissues ◽  
Response To Treatment ◽  
Deep Learning Algorithm ◽  
Cross Correlation Analysis ◽  
Porcine Eyes

Intraocular pressure (IOP) measurement is one of the basic tests performed in ophthalmology and is known to be an important risk factor for the development and progression of glaucoma. Measurement of IOP is important for assessing response to treatment and monitoring the progression of the disease in glaucoma. In this study, we investigate a method for measuring IOP using the characteristics of vibration propagation generated when the structure is in contact with the eyeball. The response was measured using an accelerometer and a force sensitive resistor to determine the correlation between the IOP. Experiment was performed using ex-vivo porcine eyes. To control the IOP, a needle of the infusion line connected with the water bottle was inserted into the porcine eyes through the limbus. A cross correlation analysis between the accelerometer and the force sensitive resistor was performed to derive a vibration factor that indicate the change in IOP. In order to analyze the degree of influence of biological tissues such as the eyelid, silicon was placed between the structure and the eyeball. The Long Short-Term Memory (LSTM) deep learning algorithm was used to predict IOP based on the vibration factor.

scholarly journals Tetracosahexaenoylethanolamide, a novel N-acylethanolamide, is elevated in ischemia and increases neuronal output

2020 ◽  
Vol 61 (11) ◽  
pp. 1480-1490
Author(s):  
Lin Lin ◽  
Adam H. Metherel ◽  
Mathieu Di Miceli ◽  
Zhen Liu ◽  
Cigdem Sahin ◽  
...  
Keyword(s):  
Nucleus Accumbens ◽  
Fatty Acid Amide Hydrolase ◽  
Ex Vivo ◽  
Acid Amide ◽  
Biological Tissues ◽  
Wild Type ◽  
Transient Transfection Assay ◽  
In The Wild ◽  
The Brain ◽  
Neuronal Output

N-acylethanolamines (NAEs) are endogenous lipid-signaling molecules derived from fatty acids that regulate numerous biological functions, including in the brain. Interestingly, NAEs are elevated in the absence of fatty acid amide hydrolase (FAAH) and following CO2-induced ischemia/hypercapnia, suggesting a neuroprotective response. Tetracosahexaenoic acid (THA) is a product and precursor to DHA; however, the NAE product, tetracosahexaenoylethanolamide (THEA), has never been reported. Presently, THEA was chemically synthesized as an authentic standard to confirm THEA presence in biological tissues. Whole brains were collected and analyzed for unesterified THA, total THA, and THEA in wild-type and FAAH-KO mice that were euthanized by either head-focused microwave fixation, CO2 + microwave, or CO2 only. PPAR activity by transient transfection assay and ex vivo neuronal output in medium spiny neurons (MSNs) of the nucleus accumbens by patch clamp electrophysiology were determined following THEA exposure. THEA in the wild-type mice was nearly doubled (P < 0.05) following ischemia/hypercapnia (CO2 euthanization) and up to 12 times higher (P < 0.001) in the FAAH-KO compared with wild-type. THEA did not increase (P > 0.05) transcriptional activity of PPARs relative to control, but 100 nM of THEA increased (P < 0.001) neuronal output in MSNs of the nucleus accumbens. Here were identify a novel NAE, THEA, in the brain that is elevated upon ischemia/hypercapnia and by KO of the FAAH enzyme. While THEA did not activate PPAR, it augmented the excitability of MSNs in the nucleus accumbens. Overall, our results suggest that THEA is a novel NAE that is produced in the brain upon ischemia/hypercapnia and regulates neuronal excitation.

Wireless Robotic Capsule for Releasing Bioadhesive Patches in the Gastrointestinal Tract

2013 ◽  
Vol 8 (1) ◽  
Author(s):  
Claudio Quaglia ◽  
Selene Tognarelli ◽  
Edoardo Sinibaldi ◽  
Nicodemo Funaro ◽  
Paolo Dario ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
Minimally Invasive ◽  
Adhesion Strength ◽  
Feasibility Study ◽  
Ex Vivo ◽  
Release Mechanism ◽  
Present System ◽  
Gi Tract ◽  
Main Application ◽  
Porcine Tissue

A novel, miniature wireless robotic capsule for releasing bioadhesive patches in the gastrointestinal (GI) tract was designed, fabricated, and preliminarily tested. In particular, the assembled prototype was successfully navigated in a GI phantom, up to a target site where the release mechanism was verified. Then, deployment of a bioadhesive patch onto ex vivo porcine tissue was accomplished, and patch adhesion strength was verified. The main application of the present system is the deployment of anchoring patches for miniature robotic modules to be operated in the targeted anatomical domain. Such an innovative application stems from the wise blend of robotics and bioadhesion. Obtained results, which are consistent with previous investigations by the group, confirm the viability of the adopted bioadhesives for the envisaged anchoring tasks. The present feasibility study complies with the spirit of minimally invasive, wireless diagnosis, and therapy, and provides a preliminary contribution for their advancement.

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