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Quality assurance (QA) guidelines are essential to provide uniform execution of clinical hyperthermia treatments and trials. This document outlines the clinical and technical consequences of the specific properties of interstitial heat delivery and specifies recommendations for hyperthermia administration with interstitial techniques. Interstitial hyperthermia aims at tumor temperatures in the 40-44 °C range as an adjunct to radiation or chemotherapy. The clinical part of this document imparts specific clinical experience of interstitial heat delivery to various tumor sites as well as recommended interstitial hyperthermia workflow and procedures. The second part describes technical requirements for quality assurance of current interstitial heating equipment including electromagnetic (radiative and capacitive) and ultrasound heating techniques. Detailed instructions are provided on characterization and documentation of the performance of interstitial hyperthermia applicators to achieve reproducible hyperthermia treatments of uniform high quality. Output power and consequent temperature rise are the key parameters for characterization of applicator performance in these QA guidelines. These characteristics determine the specific maximum tumor size and depth that can be heated adequately. The guidelines were developed by the ESHO Technical Committee with participation of senior STM members and members of the Atzelsberg Circle.
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Hipertermia Inducida/métodos , Garantía de la Calidad de Atención de Salud/métodos , Guías como Asunto , Humanos , TemperaturaRESUMEN
BACKGROUND: A new method of scheduling anesthesia-controlled time (ACT) was implemented on July 1, 2012 in an academic inpatient operating room (OR) department. This study examined the relationship between this new scheduling method and OR performance. The new method comprised the development of predetermined time frames per anesthetic technique based on historical data of the actual time needed for anesthesia induction and emergence. Seven "anesthesia scheduling packages" (0 to 6) were established. Several options based on the quantity of anesthesia monitoring and the complexity of the patient were differentiated in time within each package. STUDY DESIGN: This was a quasi-experimental time-series design. Relevant data were divided into 4 equal periods of time. These time periods were compared with ANOVA with contrast analysis: an intervention, pre-intervention, and post-intervention contrast were tested. All emergency cases were excluded. A total of 34,976 inpatient elective cases performed from January 1, 2010 to December 31, 2014 were included for statistical analyses. RESULTS: The intervention contrast showed a significant decrease (p < 0.001) of 4.5% in the prediction error. The total number of cancellations decreased to 19.9%. The ANOVA with contrast analyses showed no significant differences with respect to under- and over-used OR time and raw use. Unanticipated results derived from this study, allowing for a smoother workflow: eg anesthesia nurses know exactly which medical equipment and devices need to be assembled and tested beforehand, based on the scheduled anesthesia package. CONCLUSIONS: Scheduling the 2 major components of a procedure (anesthesia- and surgeon-controlled time) more accurately leads to fewer case cancellations, lower prediction errors, and smoother OR workflow in a university hospital setting.
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Anestesia , Citas y Horarios , Eficiencia Organizacional , Hospitales Universitarios/organización & administración , Quirófanos/organización & administración , Admisión y Programación de Personal/organización & administración , Flujo de Trabajo , Humanos , Países Bajos , Factores de TiempoRESUMEN
BACKGROUND: Guinea-pigs, classical laboratory animals now often kept as pets, regularly elicit important allergic reactions. Two guinea-pig allergens have been described previously to some extent; however, biomolecular and immunological data are lacking. OBJECTIVE: To identify major guinea-pig allergens, produce them as recombinant proteins and define their allergenic potential and clinical importance in allergic patients. METHODS: Protein extracts were prepared from various guinea-pig tissues and allergens were purified by ion exchange chromatography. The N-termini of two immunoglobulin E (IgE)-reactive proteins were determined and degenerate primers were designed for cDNA amplification by RT-PCR. Allergenic properties of recombinant proteins were assayed by immunoblotting, ELISA and mediator release assays. Specific IgE were quantified in the sera of 26 guinea-pig-allergic patients. RESULTS: Major IgE-reactive proteins were detected in submaxillary and harderian gland extracts. Two proteins were identified and the cDNAs were cloned. The 17 kDa protein expressed in the harderian gland corresponds to the previously described Cav p 2. The 19 kDa protein, Cav p 3, is a new allergen expressed in the submaxillary gland. Recombinant Cav p 2 and Cav p 3 were recognized by IgE antibodies from 65% and 54% of guinea-pig-allergic patients, respectively. Both proteins demonstrated equivalent allergenic activity in the mediator release assays. CONCLUSION AND CLINICAL RELEVANCE: Two major guinea-pig allergens, Cav p 2 and Cav p 3, have been characterized and produced as recombinant proteins. Combined to guinea-pig serum albumin, the new allergens proved to be valuable in the component-resolved diagnosis of guinea-pig allergy.
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Cobayas/inmunología , Hipersensibilidad/diagnóstico , Lipocalinas , Proteínas Recombinantes , Adolescente , Adulto , Anciano , Secuencia de Aminoácidos , Animales , Niño , Preescolar , Reacciones Cruzadas/inmunología , Epítopos/inmunología , Femenino , Humanos , Hipersensibilidad/inmunología , Hipersensibilidad/metabolismo , Inmunoglobulina E/inmunología , Inmunoglobulina E/metabolismo , Aparato Lagrimal/inmunología , Aparato Lagrimal/metabolismo , Lipocalinas/inmunología , Masculino , Persona de Mediana Edad , Datos de Secuencia Molecular , Proteínas Recombinantes/inmunología , Glándulas Salivales/inmunología , Glándulas Salivales/metabolismo , Alineación de Secuencia , Adulto JovenRESUMEN
Voxel-based morphometry (VBM) is a widely applied method in computational neurosciences but it is currently recommended to compare only data collected at a single MRI scanner. Multi-site VBM would be a desirable approach to increase group size and, thus, statistical power. We aimed to assess if multi-site VBM is feasible on similar hardware and compare the magnitude of inter- and intra-scanner differences. 18 healthy subjects were scanned in two identical 3T MRI scanners using different head coil designs, twice in scanner A and once in scanner B. 3D T1-weighted images were processed with SPM8 and FSL4.1 and compared as paired t-test (scan versus re-scan) on a voxel basis by means of a general linear model (GLM). Additionally, coefficient-of-difference (coeffD) maps were calculated for respective pairs of gray matter segmentations. We found considerable inter-scanner differences clearly exceeding a commonly used GLM significance threshold of p<0.05 (FWE corrected). The spatial pattern of detected differences was dependent on whether SPM8 or FSL4.1 was used. The inclusion of global correcting factors either aggravated (SPM8) or reduced the GLM detected differences (FSL4.1). The coeffD analysis revealed markedly higher variability within the FSL4.1 stream both for the inter- and the intra-scanner comparison. A lowered bias cutoff (30 mm FWHM) in SPM8 improved the comparability for cortical areas. Intra-scanner scan/re-scan differences were generally weaker and did not exceed a p<0.05 (FWE corrected) threshold in the GLM analysis. At 3T profound inter-scanner differences are to be expected that could severely confound an unbalanced VBM analysis. These are like related to the receive bias of the radio-frequency hardware.
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Procesamiento de Imagen Asistido por Computador/métodos , Imagen por Resonancia Magnética/métodos , Algoritmos , Mapeo Encefálico/métodos , Humanos , Modelos Lineales , Imagen por Resonancia Magnética/instrumentación , Imagen por Resonancia Magnética/estadística & datos numéricos , Análisis de Regresión , Reproducibilidad de los Resultados , Programas InformáticosRESUMEN
This paper's primary objective is to analyse the physiological (cortisol) and behavioral responses of military working dogs (MWD). Dogs (N=27) were submitted twice to environmental challenges (challenge 1 and 2, 20 days in-between) composed of social (training), visual (mobile toy car) and auditory (air blast) stimuli. Cortisol levels decreased back to the baseline after the second challenge. The behavioral observations showed that these MWD were more active, and presented less stereotypic behaviors (pacing, manipulation of the environment) during both visual challenges, whereas half low posture was observed during the first but not during the second visual challenge. The present study shows that this group of MWD still has an adaptation capacity to an environmental challenge (return to baseline of the cortisol levels, a higher posture during the second than at the first challenge). These results are encouraging and indicate that the dogs might have a diminished welfare (i.e. stereotypic behaviors), but are not chronically stressed.
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Conducta Animal/fisiología , Enfermedades de los Perros/sangre , Ambiente , Hidrocortisona/sangre , Estrés Fisiológico/veterinaria , Estrés Psicológico/sangre , Análisis de Varianza , Bienestar del Animal , Animales , Enfermedades de los Perros/psicología , Perros , Femenino , Estudios Longitudinales , Masculino , Personal Militar , Estadísticas no Paramétricas , Conducta Estereotipada/fisiología , Estrés Fisiológico/sangre , Estrés Fisiológico/psicología , Estrés Psicológico/psicología , Servicio Veterinario MilitarRESUMEN
Magnetic Resonance Imaging (MRI) is a promising tool for visualizing the delivery of minimally invasive cancer treatments such as high intensity ultrasound (HUS) and cryoablation. We use an acute dog prostate model to correlate lesion histopathology with contrast-enhanced (CE) T1 weighted MR images, to aid the radiologists in real time interpretation of in vivo lesion boundaries and pre-existing lesions. Following thermal or cryo treatments, prostate glands are removed, sliced, stained with the vital dye triphenyl tetrazolium chloride, photographed, fixed and processed in oversized blocks for routine microscopy. Slides are scanned by Trestle Corporation at .32 microns/pixel resolution, the various lesions traced using annotation software, and digital images compared to CE MR images. Histologically, HUS results in discrete lesions characterized by a "heat-fixed" zone, in which glands subjected to the highest temperatures are minimally altered, surrounded by a rim or "transition zone" composed of severely fragmented, necrotic glands, interstitial edema and vascular congestion. The "heat-fixed" zone is non-enhancing on CE MRI while the "transition zone" appears as a bright, enhancing rim. Likewise, the CE MR images for cryo lesions appear similar to thermally induced lesions, yet the histopathology is significantly different. Glands subjected to prolonged freezing appear totally disrupted, coagulated and hemorrhagic, while less intensely frozen glands along the lesion edge are partially fragmented and contain apoptotic cells. In conclusion, thermal and cryo-induced lesions, as well as certain pre-existing lesions (cystic hyperplasia - non-enhancing, chronic prostatitis - enhancing) have particular MRI profiles, useful for treatment and diagnostic purposes.
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A catheter-based transurethral ultrasound applicator with angularly directional heating patterns has been designed for prostate thermal therapy and evaluated in canine prostate in vivo using MRI to monitor and assess performance. The ultrasound transducer array (3.5 mm diameter tubular transducers, 180 degrees active sectors, approximately 7.5 MHz) was integrated to a flexible delivery catheter (4 mm OD), and encapsulated within an expandable balloon (35 mm x 10 mm OD, 80 ml min(-1) ambient water) for coupling and cooling of the prostatic urethra. These devices were used to thermally coagulate targeted portions of the canine prostate (n = 2) while using MR thermal imaging (MRTI) to monitor the therapy. MRI was also used for target definition, positioning of the applicator, and evaluation of target viability post-therapy. MRTI was based upon the complex phase-difference mapping technique using an interleaved gradient echo-planar imaging sequence with lipid suppression. MRTI derived temperature distributions, thermal dose exposures, T1-contrast enhanced MR images, and histology of sectioned prostates were used to define destroyed tissue zones and characterize the three-dimensional heating patterns. The ultrasound applicators produced approximately 180 degrees directed zones of thermal coagulation within targeted tissue which extended 15-20 mm radially to the outer boundary of the prostate within 15 min. Transducer activation lengths of 17 mm and 24 mm produced contiguous zones of coagulation extending axially approximately 18 mm and approximately 25 mm from base to apex, respectively. Peak temperatures around 90 degrees C were measured, with approximately 50 degrees C-52 degrees C corresponding to outer boundary t43 = 240 min at approximately 15 min treatment time. These devices are MRI compatible, and when coupled with multiplanar MRTI provide a means for selectively controlling the length and sector angle of therapeutic thermal treatment in the prostate.
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Neoplasias de la Próstata/terapia , Terapia por Ultrasonido , Ultrasonido , Uretra/patología , Animales , Cateterismo , Perros , Imagen Eco-Planar , Calefacción , Calor , Humanos , Imagen por Resonancia Magnética , Magnetismo , Masculino , Modelos Estadísticos , Temperatura , Factores de Tiempo , TransductoresRESUMEN
High-temperature thermal therapy for the treatment of prostate cancer is currently being applied as a minimally-invasive alternative over traditional forms of treatment. Catheter-based interstitial and transurethral ultrasound applicators are being developed for controlled and selective thermal ablation of prostaric tissues with concurrent MR thermal imaging. As part of this treatment strategy we have devised a transurethral cooling catheter and a cooling jacket to be placed over the endorectal MR imaging coil to protect the urethral mucosa and rectal wall from thermal damage during treatment. The cooling efficiencies and protective abilities of these devices were evaluated in vivo within three canine prostate glands. Invasive and MR derived temperature measurements within the prostate and rectal wall indicate that the protective influence of the endorectal cooling extends 5-10 mm from the rectal wall into the dorsal prostate. The urethral cooling extends approximately 5 mm from the cooling balloon. The protective capabilities were further verified with subsequent histological analysis with TTC stained tissue sections and contrast enhanced T1-weighted MR images post treatment. Both of these cooling devices are compatible with the MR thermometry and can be used to protect the urethral mucosa and rectal wall during prostate thermal ablation with interstitial and transurethral ultrasound devices.
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High-temperature thermal therapy is emerging as a feasible treatment option for prostate cancer and benign prostatic hyperplasia. Previous investigations have demonstrated distinct advantages of catheter-based ultrasound technology over other heating modalities for thermal ablation therapies, with significant potential for better spatial control and faster heating times. The purpose of this study was to develop ultrasound devices and techniques specifically for treating prostate cancer in conjunction with magnetic resonance thermal imaging (MRTI) to monitor and control treatment progression. Directional transurethral applicators have been designed with arrays of sectored tubular (90 degrees active acoustic sector) or with narrow planar transducer segments and integrated with a flexible delivery catheter with a cooling balloon. This applicator can be rotated within the prostatic urethra to target specific regions during treatment. MRI compatible catheter-cooled interstitial ultrasound applicators with 180 degrees active acoustic sectors were developed specifically to treat the prostate. These applicators may be implanted through the perineum into the posterior portion of the prostate, with their heating energy directed away from the rectum. Both heating strategies were evaluated via biothermal simulations and in vivo experiments within canine prostate (n = 3). During the in vivo studies, MRTI was used to monitor treatment temperatures, cytotoxic thermal doses (t43 > 240 min) and corresponding maximum temperature thresholds (Tmax > 52 degrees C) within three imaging planes simultaneously. Urethral and endorectal cooling was employed with both treatment strategies to provide further protection of the urethral mucosa and rectum from thermal damage. Results using the transurethral applicators demonstrated that narrow zones of coagulation (approximately 30 degrees sector for planar, approximately 90 degrees for tubular), extending up to 20 mm from the urethra to the periphery of the prostate gland, could be produced within 10-15 min. Further, rotation of the applicator during treatment could be used to destroy larger regions in the prostate. Experiments using multiple interstitial directional applicators (approximately 180 degrees active sectors), implanted within the posterior margin of the prostate with the energy directed away from the rectum, produced contiguous zones of thermal coagulation which extended from the posterior prostate toward the anterior-lateral periphery of the gland. Both transurethral and interstitial treatment strategies demonstrated significant potential for thermal ablation of localized prostate cancer, particularly when MRTI is used to guide and assess treatment.
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Ablación por Catéter/instrumentación , Hipertermia Inducida/instrumentación , Imagen por Resonancia Magnética , Hiperplasia Prostática/terapia , Neoplasias de la Próstata/terapia , Terapia por Ultrasonido/instrumentación , Animales , Diseño de Equipo , Humanos , Hipertermia Inducida/métodos , Masculino , Hiperplasia Prostática/cirugía , Neoplasias de la Próstata/cirugíaRESUMEN
STUDY DESIGN: Human cadaver lumbar spines were used to assess the acute effects of intradiscal electrothermal therapy in vitro. OBJECTIVE: To determine whether intradiscal electrothermal therapy produces acute changes in disc histology and motion segment stability. SUMMARY OF BACKGROUND DATA: Intradiscal electrothermal therapy has been introduced as an alternative for the treatment of discogenic low back pain. Several hypothesized mechanisms for the effect of intradiscal electrothermal therapy have been suggested including shrinkage of the nucleus or sealing of the anulus fibrosus by contraction of collagen fibers, and thermal ablation of sensitive nerve fibers in the outer anulus. METHODS: Intradiscal electrothermal therapy was performed with the Spinecath by Oratec on 19 fresh, frozen human lumbar cadaver specimens. In a separate study, eight specimens were tested biomechanically and instrumented to map the thermal distribution, whereas five specimens were tested only biomechanically, both before and after intradiscal electrothermal therapy. Six additional specimens were heated with intradiscal electrothermal therapy, and the resulting canal was backfilled with a silicone rubber compound to allow colocalization of the catheter and anular architecture. RESULTS: A consistent pattern of increased motion and decreased stiffness was observed. For the specimens in which only biomechanical measurements were taken, a 10% increase in the motion, on the average, at 5 Nm torque was observed after intradiscal electrothermal therapy. No apparent alteration of the anular architecture was observed around the catheter site in the intradiscal electrothermal therapy-treated discs. CONCLUSION: The data from this study suggest that the temperatures developed during intradiscal electrothermal therapy are insufficient to alter collagen architecture or stiffen the treated motion segment acutely.
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Electrocoagulación/métodos , Calor/efectos adversos , Desplazamiento del Disco Intervertebral/cirugía , Disco Intervertebral/cirugía , Vértebras Lumbares , Procedimientos Quirúrgicos Mínimamente Invasivos , Adulto , Anciano , Fenómenos Biomecánicos , Cadáver , Colágeno/química , Colágeno/ultraestructura , Femenino , Calor/uso terapéutico , Humanos , Técnicas In Vitro , Disco Intervertebral/patología , Disco Intervertebral/fisiología , Desplazamiento del Disco Intervertebral/complicaciones , Inestabilidad de la Articulación/fisiopatología , Dolor de la Región Lumbar/cirugía , Masculino , Persona de Mediana Edad , Desnaturalización Proteica , TemperaturaRESUMEN
Catheter-cooled (CC) interstitial ultrasound applicators were evaluated for their use in high-temperature coagulative thermal therapy of tissue. Studies in ex vivo beef muscle were conducted to determine the influences of applied electrical power levels (5-20 W per element), catheter flow rate (20-60 ml min(-1)), circulating water temperature (7-40 degrees C), and frequency (7-9 MHz) on temperature distribution and thermal lesion geometry. The feasibility of using multiple interstitial applicators to thermally coagulate a predetermined volume of tissue was also investigated. Results of these studies revealed that the directional shape of the thermal lesions is maintained with increasing time and power. Radial depths of the thermal lesions ranged from 10.7 +/- 0.7 mm after heating for 4 min with an applied power level of 5 W, to 16.2 +/- 1.4 mm with 20 W. The axial length of the thermal lesions is controlled tightly by the number of active transducers. A catheter flow rate of 20 to 40 ml min(-1) (52.2 +/- 5.5 kPa at 40 ml min(-1)) with 22 degrees C water was determined to provide sufficient cooling of the transducers for power levels used in this study. In vivo temperatures measured in the center of a 3-cm-diam peripheral implant of four applicators in pig thigh muscle reached 89.3 degrees C after 4 min of heating, with boundaries of coagulation clearly defined by applicator position and directivity. Conformability of heating in a clinically relevant model was demonstrated by inserting two directional CC applicators with a 2 cm separation within an in vivo canine prostate, and generating a thermal lesion measuring 3.8 cm x 2.2 cm in cross section while directing energy away from, and protecting the rectum. Maximum measured temperatures at midgland exceeded 90 degrees C within 20 min of heating. The results of this study demonstrate the utility of single or multiple CC applicators for conformal thermal coagulation and high temperature thermal therapy, with potential for clinical applications in sites such as prostate, liver, breast, or uterus.
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Cateterismo , Calor , Transductores , Terapia por Ultrasonido/instrumentación , Terapia por Ultrasonido/métodos , Animales , Perros , Electrocoagulación/instrumentación , Diseño de Equipo , Masculino , Próstata/patología , Neoplasias de la Próstata/terapia , Porcinos , TemperaturaRESUMEN
This study presents a comparative evaluation of the control of heating and thermal coagulation with microwave (MW) and ultrasound (US) interstitial applicators. Helical coil MW antennas (17 mm and 25 mm length radiating antennae) were tested using an external implant catheter (2.2 mm o.d.) with water-cooling. US applicators with tubular transducers (2.2 and 2.5 mm o.d., 10 mm length, single-element and 3-element) were utilized with a direct-coupled configuration and internal water-cooling. Measurements of E-field distributions (for MW) and acoustic beam distributions (for US) were used to characterize the applicator energy output. Thermal performance was evaluated through multiple heating trials in vitro (bovine liver) and in vivo (porcine thigh muscle and liver) at varied levels of applied power (20-40 W for microwave, 15-35 W for ultrasound) and heating times (0.5-5 min). Axial temperature distributions in the tissue were recorded during heating, and dimensions of the resulting lesions of thermal coagulation were measured. Both MW and US applicators produced large volumes of tissue coagulation ranging from 8 to 20 cm3 with singular heating times of 5 min. Radial depth of lesions for both MW and US applicators increased with heating duration and power levels, though US produced notably larger lesion diameters (30-42 mm for US vs 18-26 mm for MW, 5 min heating). Characteristic differences between the applicators were observed in axial energy distribution, tissue temperatures, and thermal lesion shapes. MW lesions increased significantly in axial dimensions (beyond the active applicator length) as applied power level and/or heating duration was increased, and lesion shapes were generally not uniform. US provided greater control and uniformity of heating, with energy deposition and axial extent of thermal lesions corresponding to the length of the active transducer(s). The improved ability to control the extent of thermal coagulation demonstrated by the US applicators provides greater potential to target a specific region of tissue.
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Hipertermia Inducida/métodos , Microondas/uso terapéutico , Terapia por Ultrasonido/métodos , Animales , Fenómenos Biofísicos , Biofisica , Femenino , Humanos , Hipertermia Inducida/instrumentación , Técnicas In Vitro , Porcinos , Terapia por Ultrasonido/instrumentaciónRESUMEN
Internal water-cooling of direct-coupled ultrasound (US) applicators for interstitial thermal therapy (hyperthermia and coagulative thermal therapy) was investigated. Implantable applicators were constructed using tubular US sources (360 angular acoustic emittance, approximately 7 MHz) of 10 mm length and 1.5, 1.8, 2.2, and 2.5 mm outer diameter (OD). Directional applicators were also constructed using 2.2 mm OD tubes sectored to provide active acoustic sectors of 90 degrees and 200 degrees. A water-cooling mechanism was integrated within the inner lumen of the applicator to remove heat from the inner transducer surface. High levels of convective heat transfer (2100-3800 W/m2K) were measured for practical water flow rates of 20-80 mL/min. Comparative acoustic measurements demonstrated that internal water-cooling did not significantly degrade the acoustic intensity or beam distribution of the US transducers. Water-cooling allowed substantially higher levels of applied electrical power (> 45 W) than previous designs (with air-cooling or no cooling), without detriment to the applicators. High-temperature heating trials performed with these applicators in vivo (porcine liver and thigh muscle) and in vitro (bovine liver) showed improved thermal penetration and coagulation. Radial depth of coagulation from the applicator surface ranged from 12 to 20 mm for 1-5 min of sonication with 28-W applied power. Higher powers (41 W) demonstrated increased coagulation depths (approximately 9 mm) at shorter times (15 s). Thermal lesion dimensions (angular and axial expanse) produced with directional applicators were controlled and directed, and corresponded to the active zone of the transducer. These characteristic lesion shapes were also generally unchanged with different sonication times and power, and were found to be consistent with previous coagulation studies using air-cooled applicators. The implementation of water-cooling is a significant advance for the application of ultrasound interstitial thermal therapy (USITT), providing greater treatment volumes, shorter treatment times, and the potential for treatment of highly perfused tissue with shaped lesions.
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Terapia por Ultrasonido/instrumentación , Acústica , Animales , Electrocoagulación/instrumentación , Diseño de Equipo , Femenino , Hígado/cirugía , Músculo Esquelético/cirugía , Porcinos , Temperatura , Muslo/cirugía , Transductores , AguaRESUMEN
The purpose of this study was to determine the feasibility of using a transurethral ultrasound applicator in combination with implantable ultrasound applicators for inducing thermal coagulation and necrosis of localized cancer lesions or benign disease within the prostate gland. The potential to treat target zones in the anterior and lateral portions of the prostate with the angularly directive transurethral applicator, while simultaneously treating regions of extracapsular extension and zones in the posterior prostate with the directive implantable applicators in combination with a rectal cooling bolus, is evaluated. Biothermal computer simulations, acoustic characterizations, and in vivo thermal dosimetry experiments with canine prostates were used to evaluate the performance of each applicator type and combinations thereof. Simulations have demonstrated that transurethral applicators with 180-270 degrees acoustic active zones can direct therapeutic heating patterns to the anterior and lateral prostate, implantable needles can isolate heating to the posterior gland while avoiding rectal tissue, and that the combination of applicators can be used to produce conformal heating to the whole gland. Single implantable applicators (1.8 mm OD x 10 mm long, approximately 180 degrees active sector, approximately 7 MHz, direct-coupled type) produced directional thermal lesions within in vivo prostate, with temperatures >50 degrees C extending more than 10 mm radially after 10-15 min. Combination of interstitial applicators (1-2) and a transurethral applicator (3-2.5 mm OD x 6 mm long, approximately 180 degrees active sector, 6.8 MHz, 6 mm OD delivery catheter) produced conforming temperature distributions (48-85 degrees C) and zones of acute thermal damage within 15 min. The preliminary results of this investigation demonstrate that implantable directional ultrasound applicators, in combination with a transurethral ultrasound applicator, have the potential to provide thermal coagulation and necrosis of small or large regions within the prostate gland, while sparing thermally sensitive rectal tissue.
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Hipertermia Inducida/instrumentación , Hipertermia Inducida/métodos , Próstata/diagnóstico por imagen , Ultrasonografía Intervencional/instrumentación , Ultrasonografía Intervencional/métodos , Uretra , Acústica , Animales , Simulación por Computador , Perros , Calor , Masculino , Necrosis , Neoplasias de la Próstata/diagnóstico por imagen , Neoplasias de la Próstata/terapiaRESUMEN
STUDY DESIGN: An observational follow-up. OBJECTIVES: To analyze the role of physical exercise and inactivity on the long-term outcome after active outpatient low back rehabilitation. SUMMARY OF BACKGROUND DATA: There is considerable evidence documenting the efficacy of exercise in the conservative treatment of chronic low back pain, but the role of exercises after the guided treatment period on the long-term success and maintenance of the results is not known. METHODS: One hundred twenty-five patients with low back pain, who had participated in a 12-week active low back rehabilitation program, were asked about subjective pain and disability on the average of 14 months after the treatment. The outcomes were defined as a recurrence of persistent pain and work absenteeism, and a survival or failure analysis was performed between those who had continued exercising and who had been physically inactive. RESULTS: Recurrences of persistent pain during the follow-up period were fewer (P = 0.03) among those who had maintained regular exercise habits after the treatment than among those who had been physically inactive. Similarly, work absenteeism was less (P < 0.01) among physically active than among physically inactive persons. However, patients with good outcome in pain reduction after low back pain rehabilitation were more likely to participate in physical exercise. CONCLUSIONS: Exercises are beneficial after guided treatment in the maintenance of the results of active treatment for recurrent chronic low back pain in the long term, but those with less favorable outcome in rehabilitation are less likely to participate in exercises afterward. In active treatment programs, it is recommended that exercises be incorporated after the guided treatment.
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Absentismo , Terapia por Ejercicio , Conductas Relacionadas con la Salud , Dolor de la Región Lumbar/rehabilitación , Adulto , Femenino , Estudios de Seguimiento , Humanos , Dolor de la Región Lumbar/psicología , Masculino , Movimiento , Debilidad Muscular/rehabilitación , Recurrencia , Encuestas y CuestionariosRESUMEN
Six aperture array dual concentric conductor (DCO) microwave hyperthermia applicators were studied using theoretical models to characterize power deposition (SAR) and steady state temperature distributions in perfused tissue. SAR patterns were calculated using the finite difference time domain (FDTD) numerical method, and were used as input to a finite difference thermal modeling program based on the Pennes Bio-Heat Equation in order to calculate corresponding temperature distributions. Numerous array configurations were investigated including the use of different size DCC apertures (2, 3, and 4 cm), different spacing between apertures (1.0-2.0 cm), and different water bolus thicknesses (5-15 mm). Thermal simulations were repeated using blood perfusion values ranging from 0.5 to 5 kg/m3 s. Results demonstrate the ability of DCC array applicators to effectively and uniformly heat tissue down to a depth of 7.5-10 mm below the skin surface for a large number of different combinations of DCC element size, spacing, and water bolus thickness. Results also reveal the close correlation between SAR patterns and corresponding temperature distributions, verifying that design studies of the applicator can be performed confidently by analysis of SAR, from which the thermal behavior can be estimated. These simulations are useful in the design optimization of large microwave DCC array applicators for superficial tissue heating and for identifying appropriate aperture spacing and bolus thickness parameters for different size DCC aperture arrays and tissue blood perfusion conditions.
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Hipertermia Inducida , Microondas/uso terapéutico , Humanos , Modelos Estadísticos , Modelos Teóricos , Reproducibilidad de los Resultados , Piel/efectos de la radiación , TemperaturaRESUMEN
This research represents an experimental investigation of the directional power deposition capabilities of interstitial ultrasound applicators intended for applications in hyperthermia and thermal surgery for cancerous or benign disease. Direct-coupled and catheter-cooled ultrasound applicators were fabricated using cylindrical piezoceramic transducers sectored to produce 90 degrees, 180 degrees or 270 degrees active acoustic zones. The applicators were characterized through measurements of acoustic power output and intensity beam distributions in degassed water, in vitro temperature measurements in a perfused kidney model, and in vivo temperature distributions in pig thigh muscle. The angular power deposition patterns obtained in water were closely correlated to the resultant temperature distributions measured in the perfused kidney and in vivo pig thigh muscle. These sectored catheter-cooled and direct-coupled devices both demonstrated the ability to generate high temperatures (>50 degrees C) at sustained high power output levels (6-12 W) without degradation of the ultrasound transducers. Directional control of the energy deposition from the sectored ultrasound applicators was verified with corresponding temperature profiles in both the in vitro and in vivo experiments, as well as with angularly shaped thermal lesions. This is significant in that it demonstrates that heating in the angular expanse can be controlled with interstitial ultrasound applicators, thus providing more conformal thermal therapy by directing the thermal energy in the targeted tissue while protecting non-targeted tissue from thermal damage.
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Cateterismo , Hipertermia Inducida/instrumentación , Ultrasonografía/instrumentación , Animales , Femenino , PorcinosRESUMEN
A multi-element, direct-coupled ultrasound (US) applicator with internal water cooling was investigated for axial control of interstitial thermal coagulation. A prototype implantable applicator was constructed with a linear array of three tubular PZT ultrasound transducers (each 2.5 mm OD, 10 mm length, 360 degrees emittance). Acoustic beam distributions from each element were measured and found to be collimated within the transducer length. The internally cooled applicator could sustain high levels of applied power to each transducer (0 to 40 W) and maintain acceptable applicator surface temperatures (<100 degrees C). Thermal performance of the applicator was investigated through heating trials in vivo (porcine thigh muscle and liver) and in vitro (bovine liver). The radial depth of thermal lesions produced was dependent on the applied power and sonication time and was controlled independently with power levels to each transducer element. With 18 W per element (applied electrical power) for 3 min, cylindrical thermal lesions were produced with a diameter of ~3 cm and a length ranging from 1.2 cm (with one element) to 3.5 cm (three elements). Higher powers (24 to 30 W) for 3 to 5 min provided increased depths of coagulation (~4 cm diameter lesions). Analysis of axial lesion shapes demonstrated that individual variation of power to each transducer element provided control of axial heating and depth of coagulation (for custom lesion shapes); lesion lengths corresponded to the number of active transducers. This ability to control the heating distribution dynamically along the length of the applicator has potential for improved target localization of thermal coagulation and necrosis in high temperature thermal therapy.
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Fibrilación Atrial/cirugía , Ablación por Catéter/métodos , Fibrilación Atrial/diagnóstico , Fibrilación Atrial/mortalidad , Ablación por Catéter/instrumentación , Ensayos Clínicos como Asunto , Electrocardiografía , Femenino , Estudios de Seguimiento , Humanos , Masculino , Tasa de Supervivencia , Resultado del TratamientoRESUMEN
Our current understanding is that atrial fibrillation (AF) is initiated most often by a focal trigger from the orifice of or within one of the pulmonary veins. Though mapping and ablation of these triggers appears to be curative in most patients with paroxysmal AF, there are a number of limitations to ablating focal triggers via mapping and ablating the earliest site of activation with a "point" radiofrequency lesion. One way to circumvent thesen limitations is an anatomically-guided ablative approach. By electrically isolating one or more pulmonary veins from the left atrium with a circumferential lesion, firing from within those veins would be unable to reach the body of the atrium, and thus could not trigger atrial fibrillation. We have developed a novel over-the-wire catheter design which integrates a cylindrical ultrasound transducer within a saline filled balloon, termed TTB-USA (through-the-balloon ultrasound ablation) in order to produce narrow circumferential zones of hyperthermic tissue death at the pulmonary vein ostia. Animal studies show great promise, and clinical trials will begin soon.