860 resultados para Computed assited technologies
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Aquest document se centra en els casos dels dos principals partits espanyols (PP i PSOE) i catalans (PSC i CDC) en el període immediatament després de les eleccions generals espanyoles de maig de 2008, quan aquests celebraren els seus congressos. En general, es poden distingir tres tipus d'actors: en primer lloc, els ciberactivistes que tracten d'obtenir el reconeixement formal de la seva activitat en els seus partits. Així com, els líders del partit que poden intentar promoure la presència del partit en el ciberespai, però que també poden romandre indecisos perquè no és clar l'impacte electoral a la xarxa del ciberactivisme. Finalment, alguns militants tradicionals (off-line) solen ser reticents al reconeixement del ciberactivisme perquè amenaça les recompenses previstes dins del partit. Aquest article mostra com els nostres partits varen respondre al desafiament del ciberactivisme i arriba a la conclusió que la seva situació electoral, mediada per la seva ideologia, estructura organitzativa i el tipus de militància, poden ajudar-nos a comprendre el grau diferent d'institucionalització en l'organització del partit.
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OBJECT Monoenergetic imaging with dual-energy CT has been proposed to reduce metallic artifacts in comparison with conventional polychromatic CT. The purpose of this study is to systematically evaluate and define the optimal dual-energy CT imaging parameters for specific cervical spinal implant alloy compositions. METHODS Spinal fixation rods of cobalt-chromium or titanium alloy inserted into the cervical spine section of an Alderson Rando anthropomorphic phantom were imaged ex vivo with fast-kilovoltage switching CT at 80 and 140 peak kV. The collimation width and field of view were varied between 20 and 40 mm and medium to large, respectively. Extrapolated monoenergetic images were generated at 70, 90, 110, and 130 kiloelectron volts (keV). The standard deviation of voxel intensities along a circular line profile around the spine was used as an index of the magnitude of metallic artifact. RESULTS The metallic artifact was more conspicuous around the fixation rods made of cobalt-chromium than those of titanium alloy. The magnitude of metallic artifact seen with titanium fixation rods was minimized at monoenergies of 90 keV and higher, using a collimation width of 20 mm and large field of view. The magnitude of metallic artifact with cobalt-chromium fixation rods was minimized at monoenergies of 110 keV and higher; collimation width or field of view had no effect. CONCLUSIONS Optimization of acquisition settings used with monoenergetic CT studies might yield reduced metallic artifacts.
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BACKGROUND: Positron emission tomography (PET) during the cold pressor test (CPT) has been used to assess endothelium-dependent coronary vasoreactivity, a surrogate marker of cardiovascular events. However, its use remains limited by cardiac PET availability. As multidetector computed tomography (MDCT) is more widely available, we aimed to develop a measurement of endothelium-dependent coronary vasoreactivity with MDCT and similar radiation burden as with PET. METHODS AND RESULTS: A study group of 18 participants without known cardiovascular risk factor (9F/9M; age 60±6 years) underwent cardiac PET with (82)Rb and unenhanced ECG-gated MDCT within 4h, each time at rest and during CPT. The relation between absolute myocardial blood flow (MBF) response to CPT by PET (ml·min(-1)·g(1)) and relative changes in MDCT-measured coronary artery surface were assessed using linear regression analysis and Spearman's correlation. MDCT and PET/CT were analyzed in all participants. Hemodynamic conditions during CPT at MDCT and PET were similar (P>0.3). Relative changes in coronary artery surface because of CPT (2.0-21.2%) correlated to changes in MBF (-0.10-0.52ml·min(-1)·g(1)) (ρ=0.68, P=0.02). Effective dose was 1.3±0.2mSv for MDCT and 3.1mSv for PET/CT. CONCLUSIONS: Assessment of endothelium-dependent coronary vasoreactivity using MDCT CPT appears feasible. Because of its wider availability, shorter examination time and similar radiation burden, MDCT could be attractive in clinical research for coronary status assessment.
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In this study we have demonstrated the potential of two-dimensional electrophoresis (2DE)-based technologies as tools for characterization of the Leishmania proteome (the expressed protein complement of the genome). Standardized neutral range (pH 5-7) proteome maps of Leishmania (Viannia) guyanensis and Leishmania (Viannia) panamensis promastigotes were reproducibly generated by 2DE of soluble parasite extracts, which were prepared using lysis buffer containing urea and nonidet P-40 detergent. The Coomassie blue and silver nitrate staining systems both yielded good resolution and representation of protein spots, enabling the detection of approximately 800 and 1,500 distinct proteins, respectively. Several reference protein spots common to the proteomes of all parasite species/strains studied were isolated and identified by peptide mass spectrometry (LC-ES-MS/MS), and bioinformatics approaches as members of the heat shock protein family, ribosomal protein S12, kinetoplast membrane protein 11 and a hypothetical Leishmania-specific 13 kDa protein of unknown function. Immunoblotting of Leishmania protein maps using a monoclonal antibody resulted in the specific detection of the 81.4 kDa and 77.5 kDa subunits of paraflagellar rod proteins 1 and 2, respectively. Moreover, differences in protein expression profiles between distinct parasite clones were reproducibly detected through comparative proteome analyses of paired maps using image analysis software. These data illustrate the resolving power of 2DE-based proteome analysis. The production and basic characterization of good quality Leishmania proteome maps provides an essential first step towards comparative protein expression studies aimed at identifying the molecular determinants of parasite drug resistance and virulence, as well as discovering new drug and vaccine targets.
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Keywords Diabetes mellitus; coronary artery disease; myocardial ischemia; prognostic value; single-photon emission computed tomography myocardial perfusion imaging Summary Aim: To determine the long-term prognostic value of SPECT myocardial perfusion imaging (MPI) for the occurrence of cardiovascular events in diabetic patients. Methods: SPECT MPI of 210 consecutive Caucasian diabetic patients were analysed using Kaplan-Meier event-free survival curves and independent predictors were determined by Cox multivariate analyses. Results: Follow-up was complete in 200 (95%) patients with a median period of 3.0 years (0.8-5.0). The population was composed of 114 (57%) men, age 65±10 years, 181 (90.5%) type 2 diabetes mellitus, 50 (25%) with a history of coronary artery disease (CAD) and 98 (49%) presenting chest pain prior to MPI. The prevalence of abnormal MPI was 58%. Patients with a normal MPI had neither cardiac death, nor myocardial infarction, independently of a history of coronary artery disease or chest pain. Among the independent predictors of cardiac death and myocardial infarction, the strongest was abnormal MPI (p<.0001), followed by history of CAD (Hazard Ratio (HR)= t 5.9, p=0.0001), diabetic retinopathy (HR=10.0, p=0.001) and inability to exercise (HR=7.7, p=0.02). Patients with normal 1VIPI had a low revascularisation rate of 2.4% during the follow-up period. Compared to normal MPI, cardiovascular events increased 5.2 fold for reversible defects, 8.5 fold for fixed defects and 20.1 fold for the association of both defects. Conclusion: Diabetic patients with normal MPI had an excellent prognosis independently of history of CAD. On the opposite, an abnormal MPI led to a > 5 fold increase in cardiovascular events. This emphasizes the value of SPECT MPI in predicting and risk-stratifying cardiovascular events in diabetic patients. Mots-Clés Diabète; maladie coronarienne; ischémie myocardique; valeur pronostique; tomoscintigraphie myocardique de perfusion par émission monophotonique Résumé Objectifs: Déterminer la valeur pronostique à long terme de la tomoscintigraphie myocardique de perfusion (TSMP) chez les patients diabétiques pour prédire les événements cardiovasculaires (ECV). Méthodes: Etude de 210 diabétiques caucasiens consécutifs référés pour une TSMP. Les courbes de survie ont été déterminées par Kaplan-Meier et les facteurs prédictifs indépendants par analyses multivariées de type Cox. Résultats: Le suivi a été complet chez 200 (95%) patients avec une durée médiane de 3.0 ans (0.8-50). La population était composée de 114 (57%) hommes, âge moyen 65±10 ans, avec 181 (90.5%) diabète de type 2, 50 (25%) antécédents de maladie coronarienne (AMC) et 98 (49%) patients connus pour un angor avant la TSMP. La prévalence de TSMP anormales était de 58%. Aucun décès d'origine cardiaque ou infarctus du myocarde n'est survenu chez les patients avec une TSMP normale, ceci indépendamment de leurs AMC et des douleurs thoraciques. Les facteurs prédictifs indépendants pour les ECV sont une TSMP anormale (p<.0001), les AMC (Hazard Ratio (HR)=15.9, p-0.0001), suivi de la rétinopathie diabétique (HR-10.0, p=0.001) et de l'incapacité à effectuer un exercice (HR=7.7, p=0.02). Les patients avec une TSMP normale ont présenté un taux de revascularisations de 2.4%. La présence de défauts mixtes accroît le risque d'ECV de 20.1 fois, les défauts fixes de 8.5 fois et les défauts réversibles de 5.2 fois comparés aux sujets avec une TSMP normale. Conclusion: Les patients diabétiques, coronariens ou non, avec une tomoscintigraphie myocardique de perfusion normale ont un excellent pronostique. A l'opposé, une TSMP anormale est associée à une augmentation du risque d'ECV de plus de 5 fois. Ceci confirme l'utilité de la TSMP dans la stratification du risque chez les patients diabétiques.
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Purpose: To compare MDCT, MRI and 18F-FDG PET/CT for the detection of peritoneal carcinomatosis due to ovarian cancerMethods and Materials: Fifteen women (mean age 65±) with clinical suspicion of ovarian cancer and peritoneal carcinomatosis underwent MDCT, MRI and 18F-FDG PET/CT, simultaneously and shortly performed before surgery (delay 8.1± days). According to the peritoneal cancer index nine abdominopelvic regions were defined. We applied four scores of lesion size on MDCT and MR images, while the maximal standard uptake value (SUVmax) was measured on 18F-FDG PET/CT. Three sites of lymphadenopathy and posterobasal pleural carcinomatosis were also analyzed. First, one radiologist blindly and separately read MDCT and MR images, while one nuclear physician blindly read PET/CT images grading each lesion according to four diagnostic certitudes. Secondly, all the images were reviewed jointly and compared with histopathology. Receiver operating characteristics (ROC) analysis was performed.Results: Peritoneal implants were proven in ten women (75%). Altogether, 228 abdominopelvic sites were compared. Sensitivity and specificity for MDCT was 90.2% and 90.6%, for MRI 93.5% and 86.3%, and for 18F-FDG PET/CT 92.7% and 95.7%, respectively. ROC area under the curve were 0.93 for MDCT and MRI, and 0.96 for 18F-FDG PET/CT respectively. No significant differences (p=0.11) were found between the three modalities.Conclusion: Although MRI revealed to be the most sensitive and 18F-FDG PET/CT the most specific modality, no significant differences were shown between the three techniques.
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Most patients with symptomatic internal carotid artery occlusion have a single minor or major hemispheric stroke. A minority of patients have ipsilateral retinal ischemia, recurrent strokes, or transient ischemic attacks. Whereas spontaneous carotid recanalization is rare, acute surgical recanalization has been attempted, with mixed results. Recently, acute endovascular recanalization has been performed and described as feasible and relatively safe. We describe a patient with symptom recurrence related to hemodynamic factors after occlusion of the carotid artery who was successfully treated 14 days after symptom onset.
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Aims To compare multidetector computed tomography (MDCT) with intravascular ultrasound (IVUS) and invasive quantitative coronary angiography (QCA) for assessment of coronary lesions in patients referred for suspected coronary artery disease (CAD). Methods and results We studied 57 patients (48 men; mean age: 63 +/- 10 years) who underwent 64-slice MDCT because of atypical chest pain, stable angina, or ECG abnormalities and were diagnosed with CAD. All patients subsequently underwent QCA and IVUS. We analyzed 102 coronary lesions using the three techniques. Measurements of luminal area stenosis and cross-sectional area by MDCT (72.9 +/- 7.0% and 4.5 +/- 1.8 mm(2), respectively) were in good agreement with those by IVUS [72.7 +/- 6.7% and 4.5 +/- 1.6 mm(2), respectively; Lin's concordance correlation coefficient r = 0.847; 95% confidence interval (CI) = 0.792-0.902 and r = 0.931; 95% CI = 0.906-0.956, respectively] but not QCA (r = 0.115; 95% CI = 0.040-0.189 and r = 0.433; 95% CI = 0.291-0.576, respectively). Plaque cross-sectional area and plaque volume measured by MDCT (12.4 +/- 3.8 mm(2) and 104.7 +/- 52.8 mu l, respectively) were in good agreement with those by IVUS (12.2 +/- 3.7 mm(2) and 102.8 +/- 54.1 mu l; r = 0.913; 95% CI = 0.880-0.945 and r = 0.979; 95% CI = 0.969-0.990, respectively). Remodeling index measurements by MDCT (1.22 +/- 0.22) were in good agreement with those by IVUS (r = 0.876; 95% CI = 0.831-0.922). Positive remodeling occurred in 63% of stenoses. Conclusion MDCT allows accurate noninvasive assessment of coronary stenosis, plaque burden and remodeling in patients referred for suspected CAD. Positive remodeling is a frequent finding in stable lesions. J Cardiovasc Med 12:122-130 (C) 2011 Italian Federation of Cardiology.
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BACKGROUND: Iterative reconstruction (IR) techniques reduce image noise in multidetector computed tomography (MDCT) imaging. They can therefore be used to reduce radiation dose while maintaining diagnostic image quality nearly constant. However, CT manufacturers offer several strength levels of IR to choose from. PURPOSE: To determine the optimal strength level of IR in low-dose MDCT of the cervical spine. MATERIAL AND METHODS: Thirty consecutive patients investigated by low-dose cervical spine MDCT were prospectively studied. Raw data were reconstructed using filtered back-projection and sinogram-affirmed IR (SAFIRE, strength levels 1 to 5) techniques. Image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured at C3-C4 and C6-C7 levels. Two radiologists independently and blindly evaluated various anatomical structures (both dense and soft tissues) using a 4-point scale. They also rated the overall diagnostic image quality using a 10-point scale. RESULTS: As IR strength levels increased, image noise decreased linearly, while SNR and CNR both increased linearly at C3-C4 and C6-C7 levels (P < 0.001). For the intervertebral discs, the content of neural foramina and dural sac, and for the ligaments, subjective image quality scores increased linearly with increasing IR strength level (P ≤ 0.03). Conversely, for the soft tissues and trabecular bone, the scores decreased linearly with increasing IR strength level (P < 0.001). Finally, the overall diagnostic image quality scores increased linearly with increasing IR strength level (P < 0.001). CONCLUSION: The optimal strength level of IR in low-dose cervical spine MDCT depends on the anatomical structure to be analyzed. For the intervertebral discs and the content of neural foramina, high strength levels of IR are recommended.
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PURPOSE: We investigated the incidence and distribution of post-mortem gas detected with multidetector computed tomography (MDCT) to identify factors that could distinguish artifactual gas from cardiac air embolism. MATERIAL AND METHODS: MDCT data of 119 cadavers were retrospectively examined. Gas was semiquantitatively assessed in selected blood vessels, organs, and body spaces (82 total sites). RESULTS: Seventy-four of the 119 cadavers displayed gas (62.2%; CI 95% 52.8-70.9), and 56 (75.7%) displayed gas in the heart. Most gas was detected in the hepatic parenchyma (40%), right heart (38% ventricle, 35% atrium), inferior vena cava (30% infrarenally, 26% suprarenally), hepatic veins (26% left, 29% middle, 22% right), and portal spaces (29%). Male cadavers displayed gas more frequently than female cadavers. Gas was detected 5-84 hours after death; therefore, the post-mortem interval could not reliably predict gas distribution (rho = 0.719, p < 0.0001). We found that a large amount of putrefaction-generated gas in the right heart was associated with aggregated gas bubbles in the hepatic parenchyma (sensitivity = 100%, specificity = 89.7%). In contrast, gas in the left heart (sensitivity = 41.7%, specificity = 100%) or in periumbilical subcutaneous tissues (sensitivity = 50%, specificity = 96.3%) could not predict gas due to putrefaction. CONCLUSION: This study is the first to show that the appearance of post-mortem gas follows a specific distribution pattern. An association between intracardiac gas and hepatic parenchymal gas could distinguish between post-mortem-generated gas and vital air embolism. We propose that this finding provides a key for diagnosing death due to cardiac air embolism.
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L'émergence des nouvelles technologies de la reproduction (NTR) est allée de pair avec un certain nombre de discours. Un discours promettant d'une part une extension de la palette de choix reproductifs des individus, une extension de leur liberté et de leur autonomie reproductives, dont la forme la plus extrême peut se traduire par la formule : un enfant quand je veux et comme je veux. D'autre part, un discours annonçant une série de « catastrophes » à venir, telles que l'effondrement de l'institution de la famille et la modification de l'espèce humaine. En d'autres termes, une tension entre promesses et catastrophes qui place les sociétés contemporaines face à de nombreux défis sociaux, politiques et éthiques, notamment quant à la question de la régulation de la PMA (procréation médicalement assistée) : qui peut y avoir accès ? Quelles techniques doit-on autoriser ? Ou au contraire limiter ? Tant de questions auxquelles aucune réponse simple et évidente n'existe. La diversité des réponses législatives quant à ces questions illustre cette complexité. L'éthique peut, ici, jouer un rôle fondamental. Sans toutefois prétendre donner des réponses toutes faites et facilement applicables, elle offre un espace de réflexion, le privilège de prendre une certaine distance face à des enjeux contemporains. C'est dans cette perspective que nous avons ancré ce travail de recherche en questionnant les enjeux éthiques de la PMA à partir d'une perspective de justice. Toutefois, au sein des études en bioéthique, majoritairement issues de la tradition libérale, la tension énoncée précédemment mène la bioéthique à justifier un certain nombre d'inégalités plutôt que de veiller à les dépasser. Ainsi, une évaluation de la pratique de la PMA à partir d'une perspective de la justice, exige, au préalable, une réévaluation du concept même de justice. Ce faisant, par une articulation entre l'éthique du care de Joan Tronto et l'approche des capabilités de Martha Nussbaum qui placent la vulnérabilité au coeur de la personne, nous avons proposé une conception de la justice fondée sur une anthropologie de la vulnérabilité. Cette conception nous permet d'identifier, dans le cadre de la pratique de la PMA en Suisse et en partant de la loi sur la procréation assistée (LPMA), les constructions normatives qui mènent à la non-reconnaissance et, ce faisant, à la mise à l'écart, de certaines formes de vulnérabilité : une vulnérabilité générique et une vulnérabilité socio-économique. Traitant la question de la vulnérabilité générique principalement, nos analyses ont une incidence sur les conceptions de la famille, du bien de l'enfant, de la femme et de la nature, telles qu'elles sont actuellement véhiculées par une conception naturalisée de la PMA. Répondre aux vulnérabilités identifiées, en veillant à leur donner une place, signifie alors déplacer ces conceptions naturalisées, afin que les vulnérabilités soient intégrées aux pratiques sociales et que les exigences de justice soient ainsi remplies. - The emergence of assisted reproductive technologies (ART) came along with several discourses. On the one hand a discourse promising an extension of the individuals' reproductive choices, their procreative liberty and autonomy. On the other hand a discourse announced a series of disasters to come such as the collapse of the family institution and the modification of human kind. In other words, a growing tension appears between promises and disasters and contemporary societies are facing inevitable social, political and ethical challenges, in particular with regard to the issue of ART regulation: who has access? What procedures should be authorized? Which ones should be limited? These complex questions have no simple or obvious answers. The variety of legislative responses to these questions highlights complexity. Ethics can play a fundamental role, and without claiming to give simple answers, also offer a space for reflection as well as the privilege to distance itself with regard to contemporary issues. It is in this perspective that this study questions the ethical considerations of ART in a perspective of justice. However, in previous studies in bioethics mainly following a liberal tradition, previously mentioned tension has lead bioethics to justify some inequalities instead of trying to overcome them. As a consequence, evaluating practices of ART from a perspective of justice requires to first reevaluate the concept of justice itself. In doing so we offer a conception of justice founded on the anthropology of vulnerability. This conception draws on an articulation of the ethic of care of Joan Tronto and the capability approach of Martha Nussbaum, which places vulnerability at the center of the person. This conception allows us to identify, within the framework of ARTS in Switzerland and starting with the laws of medically assisted procreation (LPMA), some normative constructions. These constructions lead to the non-recognition and the disregard of some forms of vulnerability: a generic vulnerability as well as socio-economic counterpart. Focusing mainly on the issue of generic vulnerability, our analysis has implications for the conceptions of family, the best interests of the child, woman, and nature in the way they are defined in a naturalized conception of ART. Responding to such failures by taking into account these vulnerabilities thus means to move these conceptions in order for vulnerabilities to be integrated in social practices and requirements for justice to be fulfilled.