Thesis (Ph.D.)--McMaster University, 2004. / Advisor: Dr. Harold K. Haugen. Includes bibliographical references (p. 108-111). Also available via World Wide Web.

BACKGROUND: The gold standard treatment for colorectal cancer liver metastases (CRCLM) is surgical resection. Unfortunately, the majority of patients with colorectal hepatic metastases are not candidates for resection. In recent years, several alternatives have emerged for patients whom are not resection candidates including modern systemic chemotherapy, targeted biologic treatments, regional therapies and local tumor ablation options. Microwave ablation (MWA) therapy is one such treatment alternative, based on thermal tissue ablation. This modality in concert with the most recent published literature on its use for patients with CRCLM will be reviewed in this paper. LITERATURE REVIEW FINDINGS: A structured review of the literature on ablative technologies was performed. In recent years, there has been an evolution from radiofrequency ablation (RFA) to microwave ablation therapy for the treatment of CRCLM. RFA has several limitations to its use and MWA theoretically avoids such limitations making it the currently preferable treatment option. There are limited publications comparing the use of RFA to MWA and limited publications on the use of microwave ablation for CRCLM. This paper will focus on the most recent data on MWA for CRCLM. This data can then be compared to the already published data on RFA. PROPOSED METHODS: Given the relative novel status for MWA as a treatment option for CRCLM, a potential disadvantage for its use is the perceived lack of knowledge across the medical professional spectrum. In an effort to expand the knowledge of MWA, the proposed outcomes for this study include creating a curriculum to be offered as a CME course focused for Primary Care Providers (PCPs) to provide a basis of clinical familiarity for its use. This effort will familiarize providers who may have patients diagnosed with CRCLM and also allow them to initiate the conversation about this therapy with their patients who may be candidates for this treatment. CONCLUSIONS: MWA therapy is a safe and effective treatment modality for CRCLM. Due to this new development in treating liver lesions originating from colorectal cancer, it’s imperative for providers to become familiar with these new technologies especially considering the high incidence of CRCLM. Therefore, a curriculum for PCPs will allow for a better understanding of this new technology and foster better provider-patient relationships.

Made available in DSpace on 2014-06-11T19:29:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-08-07Bitstream added on 2014-06-13T19:59:04Z : No. of bitstreams: 1 montechiesi_df_me_botfmvz.pdf: 745136 bytes, checksum: eafa1c97155a42da695e74f237e9a6fb (MD5) / Universidade Estadual Paulista (UNESP) / O presente estudo teve como objetivo verificar o efeito da aspiração de folículos 25mm sobre a concentração de progesterona plasmática em éguas. O crescimento folicular foi acompanhado diariamente e um único folículo ovariano foi aspirado, exceto quando uma co-dominância foi observada. Neste caso, ambos os folículos foram aspirados no mesmo momento quando atingiram o diâmetro esperado nos respectivos grupos: F ³25mm (n = 6), F ³30mm (n = 6), F ³35mm (n = 6), F pré-ovulatório (n = 6). O Grupo controle (n = 5) não foi submetido à aspiração, acompanhando-se as ovulações espontâneas. A avaliação ultrassonográfica dos ovários foi realizada a cada 24 horas iniciando-se 48 horas antes da aspiração folicular (D0 = dia da aspiração), continuando até a ovulação subsequente. Para a análise estatística, foi utilizada a análise de variância de perfil seguida do método de Tukey com nível de significância de 5% para todas as variáveis, exceto: (1) animais que responderam à aspiração folicular atingindo concentrações de 2ng/mL de progesterona; (2) presença ou ausência de estrutura lútea visualizada pela ultrassonografia, onde foi utilizado o teste do qui-quadrado. A concentração de progesterona foi >2ng/mL, entre os dias 4,0±0,4 e 7,3±0,5 após a aspiração. O intervalo entre a aspiração e a luteólise foi de 16,0±0,5 a 19,0±1,4 dias e entre a aspiração e a ovulação foi de 17,2±2,8 a 23±0,5 dias. A concentração máxima de progesterona alcançada variou entre 6,4±2,6 e 10,9±1,8ng/mL e ocorreu entre os dias 8,7±3,4 e 11,5±1,2. A aspiração folicular em todos os grupos permitiu que as células foliculares se transformassem em estrutura hormonalmente ativa, produtora de progesterona em níveis compatíveis com o diestro. / The present study aims to verify the follicles 25mm ablation effect on plasmatic progesterone concentration in mares. Follicular growth was daily accompanied and only one follicle was ablated, excepted when codominance was observed. At this case, both follicles were ablated at the same moment when achived the expected diameter for the following groups: F ³25mm (n = 6), F ³30mm (n = 6), F ³35mm (n = 6), F pre-ovulatory (n = 6). Control group (n = 5) was not submitted to ablation and the spontaneous ovulations were followed. Ultrasound evaluations of the ovaries were done every 24h beginning 48h after follicular ablations (D0 = day of ablation), continuing until subsequent ovulation. For statistical analysis, profile analysis followed by Tuckey method was used with a significance level of 5% for all variables excepted for: (1) animals that responded to follicular ablation achieving progesterone concentrations of 2ng/mL; (2) presence or absence of a luteum structure observed by ultrasound were analysed by Qui-square test. Interval between aspiration and luteolysis varied from 16,0±0,5 to 19,0±1,4 days and between ablation and next ovulation varied from 17,2±2,8 to 23±0,5 days. Maximum concentration of progesterone varied from 6,4±2,6 and 10,9±1,8ng/mL and occurred between days 8,7±3,4 and 11,5±1,2. In all groups, follicular ablation allowed follicular cells to become an active hormonal structure, which produced progesterone in concentrations similar to diestrous.

Atrioventricular nodal reentrant tachycardia (AVNRT) is an abnormal heart rhythm caused by aberrant electrical conduction within the AV node. AVNRT is the most common type of paroxysmal supraventricular tachycardia (PSVT), with approximately 50,000 new cases per year in the United States. Catheter ablation of AV node tissue has become the first-line definitive treatment for AVNRT, owing to its high efficacy, tolerability, and safety. Two modalities of ablation, radiofrequency (RF) and cryoablation are commonly utilized in clinical practice with high levels of success in treating AVNRT. To date, studies on the two modalities have compared metrics such as acute success rate, procedure time, fluoroscopy time, and recurrence of AVNRT. Recurrence of AVNRT has been observed as far as 10 years after RF ablation. In patients with a history of RF ablation for AVNRT, rates of atrial fibrillation are higher than that of the general population. However, long-term studies directly comparing RF and cryoablation outcomes do not exist. This retrospective cohort study is designed to examine the rates of AVNRT recurrence and new arrythmias in patients 10 to 15 years after receiving either RF or cryoablation. To accomplish this, eligible participants will have their medical records reviewed for documentation of AVNRT recurrence, atrial fibrillation, atrial flutter, and complete AV block requiring pacemaker implantation. In doing so, we hope to give providers more insight into the risk profiles for each modality.

OBJECTIVE: To determine overall patient satisfaction with the balloon endometrial ablation procedure in women with menorrhagia. STUDY DESIGN: Thirty-one women in a university hospital underwent thermal balloon endometrial ablation in the year 2000. Of these, 3 were lost to follow-up. Twenty-eight women were called and asked to participate in a survey that quantified overall satisfaction with the procedure as well as change in menstrual flow and menstrual pain. Women were asked if any further medical or surgical therapy was required to control the bleeding. All patients participated in the study and stated that they underwent the procedure secondary to "heavy bleeding." All operative reports were reviewed and contained menorrhagia, menometorrhagia or dysfunctional uterine bleeding in the preoperative diagnosis. RESULTS: A total of 57% of women reported overall satisfaction with the endometrial ablation procedure, 14% were very dissatisfied, and 4% were neutral. Fifty-seven percent of women reported no bleeding or very decreased bleeding following the procedure, while 11% had slightly decreased bleeding. Thirty-two percent experienced no change, 43% reported decreased menstrual pain, and 57% had no change. Thirteen of 28 women underwent subsequent hysterectomy. CONCLUSION: Less than 60% of women reported saatisfaction with balloon endometrial ablation; and 40% underwent hysterectomy within 1 year of it.

The increasing demand for efficient cancer treatment inspired the researchers for new investigations about an alternative treatment of cancer. Microwave ablation is the newest ablation technique to cure cancer. This method is minimally noninvasive and inexpensive compared to the other methods. However, current microwave ablation systems suffer due to narrowband nature of the antenna (dipole or slot) placed at the tip of the probe. Therefore, this study developed an ultra-wideband ablation probe that operates from 300MHz to 10 GHz. For this purpose, a small wideband antenna is designed to place at the tip of the probe and fabricated. These probes are tested at ISM frequencies (2.4 GHz and 5.8GHz) in skin mimicking gels and pig liver. Microwave ablation probe design, simulation results, and experiment results are provided in this thesis.

In recent years, microwave ablation therapy has become widely investigated as an alternative treatment to cancer. This method is one of the newest forms of ablation techniques for the removal of tumors and is minimally invasive compared to alternative treatments. One drawback to many of the current microwave ablation systems is the narrowband nature of the antennas used for the probe, such as dipole antennas. This study aims to compare ablation results of both ultra-wideband and narrowband ablation techniques. An ultra-wideband ablation probe is designed that operates from 400MHz to 2.6GHz and are compared to two designed narrowband ablation probes that operate at 915MHz and 2.4GHz, respectively. These ablation probes are tested in tissue mimicking gels and porcine liver. Provided results for this thesis will include probe designs, simulation results, and ablation experiments.

Ti: sapphire femtosecond laser ablation of dielectrics (fused silica and BK7 glass) and metals (Cu, Fe, Al) is presented. Results of laser -induced breakdown experiments in fused silica and BK7 glass employing 130 fs -1.7 ps, 790 nm laser pulses are reported. The fluence ablation threshold does not follow the scaling of ~ when pulses are shorter than 1 ps. Single-shot and multi-shot (130 fs pulse) ablation of selected materials are investigated with laser wavelengths of 395 nm, 790 nm, and 1300 nm. The ablation threshold is almost independent of the laser wavelength. The surface morphologies in metals after ultrashort pulse ablation are very different from dielectrics and semiconductors. The roughness of the ablated surface depends on the thermal properties of the metal target. The preliminary TEM result from Cu single crystal that was irradiated by single laser pulses shows few defects in the center region of the ablated crater. Single-shot ablation of single-crystal Fe induces much different surface features than on selected samples of poly-crystal Fe metal. / Thesis / Master of Engineering (ME)

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.

The ultimate objective of the research which led to this thesis is to increase the efficacy and safety of radiofrequency catheter ablation (RFCA) of cardiac tissue. The purpose of RFCA is to carefully heat selected locations in the heart. The resulting thermal injury creates lesions which prevent the generation or propagation of arrhythmias. The ability to predict the appropriate amount of energy required at any ablation site is essential to increasing the efficacy and safety of RFCA. The research documented in this thesis focuses on the development of an approximate thermal model of the time-dependent temperature profile within the myocardium during an RFCA procedure. It is anticipated that this model will ultimately give electrophysiologists the ability to accurately titrate energy delivery in clinical situations. The approximate thermal model uses a convective boundary condition to account for convective cooling of the myocardial surface. This model also uses a point source rather than the complicated heat generation function that accounts for the spatial variation of the voltage in the cardiac tissue. A C program was written to evaluate the engineering model. The effect of the convection coefficient (h), the depth at which the point source is located (zo), and the power dissipation rate (P) on the 50 ˚C isotherm in the cardiac tissue is shown. The accuracy of the approximate model depends greatly on the values of these three parameters. Rigorous three-dimensional numerical modeling was done in order to validate the engineering model. The numerical model was done using a commercial computational fluid dynamics (CFD) package. This software solved the steady, incompressible Reynolds-Averaged Navier-Stokes (RANS) equations—along with the Reynolds-Averaged energy transport equation—using an unstructured, segregated, pressure-based finite-volume procedure. This model is different from other numerical RF ablation models in that it took into account the turbulent flow of the blood. It also accounted for the effect of the flow past the electrode and the spatially varying heat generation function. The heat generation function was found from the solution of the Laplace equation to find the voltage distribution in the tissue. The three unknown parameters governing the approximate thermal model were changed manually and good fits of the approximate model with the numerical model resulted, proving that the engineering model can accurately predict the size of the 50 ˚C isotherm in the cardiac tissue.