Radiofrequency ablation (RFA) is a clinic tool for the treatment of various target tissues. However, one of the major limitations with RFA is the ‘small’ size of target tissues that can be effectively ablated. By small it is meant the size of the target tissue is less than 3 cm in diameter of the tissue otherwise ‘large’ size of tissue in this thesis. A typical problem with RFA for large target tissue is the incompleteness of tumour ablation, which is an important reason for tumour recurring. It is widely agreed that two reasons are responsible for the tumour recurring: (1) the tissue charring and (2) the ‘heat-sink’ effect of large blood vessels (i.e. ≥3 mm in diameter). This thesis study was motivated to more quantitatively understand tissue charring during the RFA procedure and to develop solutions to increase the size of target tissues to be ablated. The thesis study mainly performed three tasks: (1) evaluation of the existing devices and protocols to give a clear understanding of the state of arts of RFA devices in clinic, (2) development of an accurate mathematical model for the RFA procedure to enable a more quantitative understanding of the small target tissue size problem, and (3) development of a new protocol based on the existing device to increase the size of target tissues to be ablated based on the knowledge acquired from (1) and (2). In (1), a design theory called axiomatic design theory (ADT) was applied in order to make the evaluation more objective. In (2), a two-compartment finite element model was developed and verified with in vitro experiments, where liver tissue was taken and a custom-made RFA system was employed; after that, three most commonly used internally cooled RFA systems (constant, pulsed, and temperature-controlled) were employed to demonstrate the maximum size of tumour that can be ablated. In (3) a novel feedback temperature-controlled RFA protocol was proposed to overcome the small target tissue size problem, which includes (a) the judicious selection of control areas and target control temperatures and (b) the use of the tissue temperature instead of electrode tip temperature as a feedback for control. The conclusions that can be drawn from this thesis are given as follows: (1) the decoupled design in the current RFA systems can be a critical reason for the incomplete target tissue necrosis (TTN), (2) using both the constant RFA and pulsed RFA, the largest TTN can be achieved at the maximum voltage applied (MVA) without the roll-off occurrence. Furthermore, the largest TTN sizes for both constant RFA and pulsed RFA are all less than 3 cm in diameter, (3) for target tissues of different sizes, the MVA without the roll-off occurrence is different and it decreases with increase of the target tissue size, (4) the largest TTN achieved by using temperature-controlled RFA under the current commercial protocol is still smaller 3 cm in diameter, and (5) the TTN with and over 3 cm in diameter can be obtained by using temperature-controlled RFA under a new protocol developed in this thesis study, in which the temperature of target tissue around the middle part of electrode is controlled at 90 ℃ for a standard ablation time (i.e. 720 s). There are a couple of contributions with this thesis. First, the underlying reason of the incomplete TTN of the current commercially available RFA systems was found, which is their inadequate design (i.e. decoupled design). This will help to give a guideline in RFA device design or improvement in the future. Second, the thesis has mathematically proved the empirical conclusion in clinic that the limit size of target tissue using the current RFA systems is 3 cm in diameter. This has advanced our understanding of the limit of the RFA technology in general. Third, the novel protocol proposed by the thesis is promising to increase the size of TTN with RFA technology by about 30%. The new protocol also reveals a very complex thermal control problem in the context of human tissues, and solving this problem effectively gives implication to similar problems in other thermal-based tumour ablation processes.

<p>This dissertation investigates the use of intraprocedure acoustic radiation force impulse (ARFI) imaging for visualization of radiofrequency ablation (RFA) lesions during cardiac transcatheter ablation (TCA) procedures. Tens of thousands of TCA procedures are performed annually to treat atrial fibrillation (AF) and other cardiac arrhythmias. Despite the use of sophisticated electroanatomical mapping (EAM) techniques to validate the modification of the electrical substrate, post-procedure arrhythmia recurrence is common due to incomplete lesion delivery and electrical conduction through lesion line discontinuities. The clinical demand for an imaging modality that can visually confirm the presence and completeness of RFA lesion lines motivated this research.</p><p>ARFI imaging is an ultrasound-based technique that transmits radiation force impulses to locally displace tissue and uses the tissue deformation response to generate images of relative tissue stiffness. RF-induced heating causes irreversible tissue necrosis and contractile protein denaturation that increases the stiffness of the ablated region. Preliminary in vitro and in vivo feasibility studies determined RF ablated myocardium appears stiffer in ARFI images.</p><p>This thesis describes results for ARFI imaging of RFA lesions for three research milestones: 1) an in vivo experimental verification model, 2) a clinically translative animal study, and 3) a preliminary clinical feasibility trial in human patients. In all studies, 2-D ARFI images were acquired in normal sinus rhythm and during diastole to maximize the stiffness contrast between the ablated and unablated myocardium and to minimize the bulk cardiac motion during the acquisition time.</p><p>The first in vivo experiment confirmed there was a significant decrease in the measured ARFI-induced displacement at ablation sites during and after focal RFA; the displacements in the lesion border zone and the detected lesion area stabilized over the first several minutes post-ablation. The implications of these results for ARFI imaging methods and the clinical relevance of the findings are discussed.</p><p>The second and third research chapters of this thesis describe the system integration and implementation of a multi-modality intracardiac ARFI imaging-EAM system for intraprocedure lesion evaluation. EAM was used to guide the 2-D ARFI imaging plane to targeted ablation sites in the canine right atrium (RA); the presence of EAM lesions markers and conduction disturbances in the local activation time (LAT) maps were used to find the sensitivity and specificity of predicting the presence of RFA lesion with ARFI imaging. The contrast and contrast-to-noise ratio between RFA lesion and unablated myocardium were calculated for ARFI and conventional ICE images. The opportunities and potential developments for clinical translation are discussed. </p><p>The last research chapter in this thesis describes a feasibility study of intracardiac ARFI imaging of RFA lesions in clinical patients. ARFI images of clinically relevant ablation sites were acquired, and this pilot study determined ARFI-induced displacements in human myocardium decreased at targeted ablation sites after RF-delivery. The challenges and successes of this pilot study are discussed.</p><p>This work provides evidence that intraprocedure ARFI imaging is a promising technology for the visualization of RFA lesions during cardiac TCA procedures. The clinical significance of this research is discussed, as well as challenges and considerations for future iterations of this technology aiming for clinical translation.</p> / Dissertation

Surgical resection is the best option for both liver and kidney cancers, which providing the long term survival. However intraoperative blood loss can be a significant challenge, and is clearly associated with morbidity and mortality. Radiofrequency ablation (RFA) precoagulation has been introduced into liver and kidney surgery. Promising results have already achieved in reduction of intraoperative blood loss. In this thesis, a detailed explanation on precoagulation by RFA has been given. Our group developed a novel bipolar multi-array RFA device ??? InLine (ILRFA). In this thesis, we have investigated the performance in a variety of fields. In the study of ILRFA-assisted laparoscopic liver resection, ILRFA was easily employed through a hand port and achieved significant decrease of blood loss compared to control group (p < 0.05). In the liver trauma study, ILRFA produced a 63.88% reduction of blood loss in peripheral injury and 53.57% in central injury respectively. In postoperative evaluation of ILRFA-assisted liver resection, animals underwent an uneventful recovery, no complications occurred. Histological examination revealed a typical post RFA evolution. In ILRFA-assisted partial nephrectomy, the mean intraoperative blood loss 35 ?? 7 ml in the ILRFA and 152 ?? 94 ml in the control, a 77.0% reduction (P = 0.024). The mean blood loss per centimetre resection area was 2.09 ?? 1.41 ml/cm2 in the ILRFA compared with 12.79 ?? 1.68 ml/cm2 in controls, the reduction was 79.0% (P = 0.019). In ILRFAassisted laparoscopic partial nephrectomy, the mean intraoperative blood loss was 32 ?? 15 ml in the ILRFA and 187 ?? 69 ml in the control group, a 77.0% reduction (P = 0.043). The mean blood loss per centimetre resection area was 2.27 ?? 0.95 ml/cm2 in the ILRFA compared with 26.46 ?? 8.81 ml/cm2 in controls, the reduction was 79.0% (P = 0.047). In the renal trauma experiment, ILRFA also achieved promising results in haemostasis. We believe that ILRFA is a useful device which may help in the treatment of patients with liver and kidney illness.

MUDr. SKALICKÝ, Tomáš Five year period of experimental and clinical experience with radiofrequency ablation of liver tumors is described. RFA considerably extends the survival of patients with non-resectable liver metastases. The method has minimal complications and both mortality and morbidity are low.

Cette thèse présente l’étude d’un réseau de capteurs pour la surveillance en temps réel de la qualité des eaux souterraines. L’objectif est de réussir à communiquer dans la bande de fréquences libre à 433MHz sur plusieurs dizaines de kilomètres. Le problème majeur des bandes libres est la présence de transmissions parasites (brouilleurs). Nous avons donc, en premier lieu, mis en évidence de la présence de ces brouilleurs et étudier leur impact sur les communications. Après analyse, il s’avère que les brouilleurs sont très nombreux et puissants mais que leur répartition dans la bande est inégale. Une étude spectrale de la bande semble nécessaire, avant la mise en place du réseau, afin de transmettre dans les canaux les moins pollués. Des communications nocturnes sont également à privilégier car les brouilleurs sont moins nombreux la nuit. Nous présentons ensuite une architecture réseau, adaptée au cahier des charges et à cette bande de fréquences. Nous avons également testé un composant RF dédié aux transmissions en bande ISM. Les résultats montrent que les performances de ce composant sont faibles pour des communications longues distances en présence de brouilleurs. Un récepteur radiofréquence simple ne permet donc pas de réaliser des communications fiables dans ces conditions. Le prototype complet du réseau, développé durant ces travaux, est ensuite décrit. Pour finir, nous proposons un nouveau concept de récepteur, utilisant un réseau d’antennes phasé et un détecteur cyclostationnaire, pour pallier au problème des brouilleurs. Le but est de stocker les signaux reçus pour les traiter en temps différé à l’aide d’algorithmes de filtrage spatial. Des simulations montrent l’efficacité de ce concept. / This thesis presents the study of a wireless sensor network for real-time monitoring of groundwater quality. The aim is to successfully communicate in the free 433MHz frequency band over tens of kilometers. The main issue of free bands is the presence of radio frequency interferences (RFI). First, we have studied the properties of these RFI and there impacts on communications. This analysis shows numerous and powerful jammers but with an irregular distribution in time and frequency. In consequence, the network set-up should be based on prior analysis of the time-frequency context. In particular, night communications should be preferred. Then, we present a network architecture adapted to the given industrial specifications and the mentioned frequency band constraint. We have also tested a RF component suitable for ISM band transmissions. Results show that the component performances are low for longue range communications with RFI. With a simple radio frequency receiver, reliable communications are not possible in these conditions. Then the complete network prototype, developed during this thesis, is described. Finally, to overcome the problem due to jammers, we propose a new receiver concept. It is based on a phased antenna array and a cyclostationary detector. The aim is to detect the signal of interest among RFI and to store it for further signal processing. In particular, off-line spatial filtering techniques can used to remove RFI. Simulations show the efficiency of this concept.

Orientadores Hugo Enrique Hernández Figueroa, Arismar Cerqueira Sodré Junior: / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação. / Made available in DSpace on 2018-08-20T15:01:09Z (GMT). No. of bitstreams: 1 Andrade_TomasPowellVillena_M.pdf: 5215489 bytes, checksum: ac57ac4162ff7586bb1be7c096aaf290 (MD5) Previous issue date: 2011 / Resumo: O avanço das telecomunicações, em particular das comunicações ópticas e sem fio, exige o desenvolvimento de soluções tecnológicas de alto desempenho para suprir a demanda crescente de serviços de transmissão de dados. Este trabalho visa contribuir para este contexto por meio da proposta e implementação de uma nova técnica para geração de sinais micro-ondas multi-nível no domínio óptico. Até o momento, as comunicações sem fio comerciais, que utilizam modulação por amplitude, são do tipo binário. A aplicação da técnica proposta permite a geração de sinais de radiofrequência (RF) na faixa de micro-ondas com modulação multi-nível, com a finalidade de permitir maiores taxas de transmissão de dados digitais ocupando uma mesma largura de banda de um sinal binário. O objetivo deste trabalho é a geração experimental de sinais digitais multi-nível na frequência de 20 GHz. Para tal, são criadas portadoras de RF a partir do batimento de dois sinais na banda C óptica, previamente moduladas com sinais digitais. Além disso, são apresentadas simulações computacionais para avaliar a viabilidade do trabalho experimental / Abstract: The advances in telecommunications, particularly for optical and wireless communications, require the development of high-performance technology solutions to meet the growing demand for data transmission services. This work aims to contribute to this context through the proposition and implementation of a new technique for generating microwave signals multi-level in the optical domain. So far, the wireless communications business, using amplitude modulation is of type binary. The application of the proposed technique allows the generation of radiofrequency signals (RF) in the range of microwaves with multi-level modulation, in order to allow higher transmission rates of digital data occupying the same bandwidth of a binary signal. The objective of this work is the experimental generation of multi-level digital signals at a frequency of 20 GHz. To this end, carriers are created from the RF beating of two C-band optical signals previously modulated with digital signals. Furthermore, computer simulations are presented to evaluate the feasibility of experimental work / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

No description available.

Les métastases hépatiques compliquent l'évolution de 50% des cancers colorectaux (CCR). Plus de la moitié des patients présentent une récidive à distance avec métastases occultes pour lesquelles une chirurgie peut être réalisée dans moins de 20% des cas. L'ablation par radiofréquence (RFA) induit une réponse lymphocytaire T qui n'est pas évaluée après une intervention chirurgicale seule. L'immunothérapie combinée à la RFA pourrait potentialiser cet effet conduisant à une réponse tumorale à distance. Nous proposons une approche qui combine la RFA avec hydrogel thermoreversible libérant des agents immunomodulateurs (GMCSF et BCG) sur le site du traitementPremièrement, nous nous sommes intéressés à la sélection et à la caractérisation de la formulation optimale d’hydrogel par des techniques physicochimiques. Les propriétés de l'hydrogel ont été étudiées par rhéologie et des tests de muco-adhésion ont été mis en place. Le temps de résidence de l'hydrogel et de la protéine dans la zone tumorale a été démontré par imagerie optique. De plus, la cinétique de libération et l'intégrité du GMCSF encapsulé ont été déterminées. Ensuite, nous avons démontré l’efficacité de l’association de la RFA avec le dépôt local de l’hydrogel immunomodulatuer sur un modèle murin de cancer colorectal. En effet, nous avons observé une survie améliorée des animaux et régression complète des tumeurs distantes chez les animaux traités par la combinaison complète. Cette réponse est caractérisée par un niveau élevé de sécrétion de cytokines pro-inflammatoires par les cellules T CD4 et TCD8 et une augmentation de l’infiltrat lymphocytaire dans les tumeurs. Ceci a permis d'envisager une association avec l'immunothérapie anti-PD1 dans le traitement de macrométastases échappant au traitement combiné RFA avec l’hydrogel immunomodulateur. En effet, l’immunothérapie dans le traitement du cancer colorectal métastatique présente une efficacité limitée chez les patients. Notre travail propose a démontré que l’efficacité de l’immunomodulation locale dans l’amélioration des réponses immunitaires dans le cancer colorectal. Ces résultats permettent de reconsidérer l’utilisation de l’immunothérapie chez les patients atteints de CCR métastatique non MSI. / Liver metastases complicate the progression of 50% of colorectal cancers (CRC). More than half of the patients have recurrent remissions with occult metastases for which surgery can be performed in less than 20% of cases. Radiofrequency ablation (RFA) induces a T lymphocyte response that is not observed after surgery alone. Combined immunotherapy with RFA may potentiate this effect leading to a distant tumor response. We propose an approach that combines RFA with thermoreversible hydrogel releasing immunomodulatory agents (GMCSF and BCG) at the treatment site.First, we focused on the selection and characterization of the optimal hydrogel formulation by physicochemical techniques. The properties of the hydrogel were studied by rheology and mucoadhesion tests were set up. The residence time of the hydrogel and the protein in the tumor zone was demonstrated by optical imaging. In addition, the release kinetics and integrity of the encapsulated GMCSF were determined. Then, we demonstrated the effectiveness of the combination of RFA with the local deposition of the immunomodulatory hydrogel on a mouse model of colorectal cancer. Indeed, we observed improved survival of animals and complete regression of distant tumors the complete treatment group. This response is characterized by a high level of pro-inflammatory cytokine secreted by CD4 and TCD8 T cells and an increase Lymphocytes infiltrating tumors. The immune escape of large lesions was reversed by association with anti-PD1 immunotherapy Indeed, immunotherapy in the treatment of metastatic colorectal cancer has limited efficacy in patients. Our work has demonstrated the effectiveness of local immunomodulation in improving immune responses in colorectal cancer. These results make it possible to reconsider the use of immunotherapy in patients with non-MSI metastatic CRC.

Marfan's syndrome is a common connective tissue disease with different musculoskeletal, ophthalmic and cardiac manifestations. Marfan's patients carry increased risk for cardiac arrhythmias. Only three cases of atrial flutter in Marfan's patients are described in the literature. We report a fourth case of a young Marfan's patient who presents with typical atrial flutter after motor vehicle accident. After electrical cardioversion, sinus rhythm was restored but he had recurrent atrial flutter on follow up. The patient then underwent electrophysiological study and successful radiofrequency catheter ablation of the flutter circuit. Since discharge, the patient has had no documented arrhythmias on follow up.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20809号 / 医博第4309号 / 新制||医||1025(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 妹尾 浩, 教授 坂井 義治, 教授 戸井 雅和 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM