974 resultados para Perfusion Spect


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Simulation is a useful tool in cardiac SPECT to assess quantification algorithms. However, simple equation-based models are limited in their ability to simulate realistic heart motion and perfusion. We present a numerical dynamic model of the left ventricle, which allows us to simulate normal and anomalous cardiac cycles, as well as perfusion defects. Bicubic splines were fitted to a number of control points to represent endocardial and epicardial surfaces of the left ventricle. A transformation from each point on the surface to a template of activity was made to represent the myocardial perfusion. Geometry-based and patient-based simulations were performed to illustrate this model. Geometry-based simulations modeled ~1! a normal patient, ~2! a well-perfused patient with abnormal regional function, ~3! an ischaemic patient with abnormal regional function, and ~4! a patient study including tracer kinetics. Patient-based simulation consisted of a left ventricle including a realistic shape and motion obtained from a magnetic resonance study. We conclude that this model has the potential to study the influence of several physical parameters and the left ventricle contraction in myocardial perfusion SPECT and gated-SPECT studies.

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PURPOSE: To prospectively determine the accuracy of 64-section computed tomographic (CT) angiography for the depiction of coronary artery disease (CAD) that induces perfusion defects at myocardial perfusion imaging with single photon emission computed tomography (SPECT), by using myocardial perfusion imaging as the reference standard. MATERIALS AND METHODS: All patients gave written informed consent after the study details, including radiation exposure, were explained. The study protocol was approved by the local institutional review board. In patients referred for elective conventional coronary angiography, an additional 64-section CT angiography study and a myocardial perfusion imaging study (1-day adenosine stress-rest protocol) with technetium 99m-tetrofosmin SPECT were performed before conventional angiography. Coronary artery diameter narrowing of 50% or greater at CT angiography was defined as stenosis and was compared with the myocardial perfusion imaging findings. Quantitative coronary angiography served as a reference standard for CT angiography. RESULTS: A total of 1093 coronary segments in 310 coronary arteries in 78 patients (mean age, 65 years +/- 9 [standard deviation]; 35 women) were analyzed. CT angiography revealed stenoses in 137 segments (13%) corresponding to 91 arteries (29%) in 46 patients (59%). SPECT revealed 14 reversible, 13 fixed, and six partially reversible defects in 31 patients (40%). Sensitivity, specificity, and negative and positive predictive values, respectively, of CT angiography in the detection of reversible myocardial perfusion imaging defects were 95%, 53%, 94%, and 58% on a per-patient basis and 95%, 75%, 96%, and 72% on a per-artery basis. Agreement between CT and conventional angiography was very good (96% and kappa = 0.92 for patient-based analysis, 93% and kappa = 0.84 for vessel-based analysis). CONCLUSION: Sixty-four-section CT angiography can help rule out hemodynamically relevant CAD in patients with intermediate to high pretest likelihood, although an abnormal CT angiography study is a poor predictor of ischemia.

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UNLABELLED The purpose of this study was to evaluate the reproducibility of a new software based analysing system for ventilation/perfusion single-photon emission computed tomography/computed tomography (V/P SPECT/CT) in patients with pulmonary emphysema and to compare it to the visual interpretation. PATIENTS, MATERIAL AND METHODS 19 patients (mean age: 68.1 years) with pulmonary emphysema who underwent V/P SPECT/CT were included. Data were analysed by two independent observers in visual interpretation (VI) and by software based analysis system (SBAS). SBAS PMOD version 3.4 (Technologies Ltd, Zurich, Switzerland) was used to assess counts and volume per lung lobe/per lung and to calculate the count density per lung, lobe ratio of counts and ratio of count density. VI was performed using a visual scale to assess the mean counts per lung lobe. Interobserver variability and association for SBAS and VI were analysed using Spearman's rho correlation coefficient. RESULTS Interobserver agreement correlated highly in perfusion (rho: 0.982, 0.957, 0.90, 0.979) and ventilation (rho: 0.972, 0.924, 0.941, 0.936) for count/count density per lobe and ratio of counts/count density in SBAS. Interobserver agreement correlated clearly for perfusion (rho: 0.655) and weakly for ventilation (rho: 0.458) in VI. CONCLUSIONS SBAS provides more reproducible measures than VI for the relative tracer uptake in V/P SPECT/CTs in patients with pulmonary emphysema. However, SBAS has to be improved for routine clinical use.

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PURPOSE To evaluate the utility of attenuation correction (AC) of V/P SPECT images for patients with pulmonary emphysema. MATERIALS AND METHODS Twenty-one patients (mean age 67.6 years) with pulmonary emphysema who underwent V/P SPECT/CT were included. AC/non-AC V/P SPECT images were compared visually and semiquantitatively. Visual comparison of AC/non-AC images was based on a 5-point likert scale. Semiquantitative comparison assessed absolute counts per lung (aCpLu) and lung lobe (aCpLo) for AC/non-AC images using software-based analysis; percentage counts (PC = (aCpLo/aCpLu) × 100) were calculated. Correlation between AC/non-AC V/P SPECT images was analyzed using Spearman's rho correlation coefficient; differences were tested for significance with the Wilcoxon rank sum test. RESULTS Visual analysis revealed high conformity for AC and non-AC V/P SPECT images. Semiquantitative analysis of PC in AC/non-AC images had an excellent correlation and showed no significant differences in perfusion (ρ = 0.986) or ventilation (ρ = 0.979, p = 0.809) SPECT/CT images. CONCLUSION AC of V/P SPECT images for lung lobe-based function imaging in patients with pulmonary emphysema do not improve visual or semiquantitative image analysis.

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ABSTRACT: BACKGROUND: Perfusion-cardiovascular magnetic resonance (CMR) is generally accepted as an alternative to SPECT to assess myocardial ischemia non-invasively. However its performance vs gated-SPECT and in sub-populations is not fully established. The goal was to compare in a multicenter setting the diagnostic performance of perfusion-CMR and gated-SPECT for the detection of CAD in various populations using conventional x-ray coronary angiography (CXA) as the standard of reference. METHODS: In 33 centers (in US and Europe) 533 patients, eligible for CXA or SPECT, were enrolled in this multivendor trial. SPECT and CXA were performed within 4 weeks before or after CMR in all patients. Prevalence of CAD in the sample was 49% and 515 patients received MR contrast medium. Drop-out rates for CMR and SPECT were 5.6% and 3.7%, respectively (ns). The study was powered for the primary endpoint of non-inferiority of CMR vs SPECT for both, sensitivity and specificity for the detection of CAD (using a single-threshold reading), the results for the primary endpoint were reported elsewhere. In this article secondary endpoints are presented, i.e. the diagnostic performance of CMR versus SPECT in subpopulations such as multi-vessel disease (MVD), in men, in women, and in patients without prior myocardial infarction (MI). For diagnostic performance assessment the area under the receiver-operator-characteristics-curve (AUC) was calculated. Readers were blinded versus clinical data, CXA, and imaging results. RESULTS: The diagnostic performance (= area under ROC = AUC) of CMR was superior to SPECT (p = 0.0004, n = 425) and to gated-SPECT (p = 0.018, n = 253). CMR performed better than SPECT in MVD (p = 0.003 vs all SPECT, p = 0.04 vs gated-SPECT), in men (p = 0.004, n = 313) and in women (p = 0.03, n = 112) as well as in the non-infarct patients (p = 0.005, n = 186 in 1-3 vessel disease and p = 0.015, n = 140 in MVD). CONCLUSION: In this large multicenter, multivendor study the diagnostic performance of perfusion-CMR to detect CAD was superior to perfusion SPECT in the entire population and in sub-groups. Perfusion-CMR can be recommended as an alternative for SPECT imaging. TRIAL REGISTRATION: ClinicalTrials.gov, Identifier: NCT00977093.

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A crucial method for investigating patients with coronary artery disease (CAD) is the calculation of the left ventricular ejection fraction (LVEF). It is, consequently, imperative to precisely estimate the value of LVEF--a process that can be done with myocardial perfusion scintigraphy. Therefore, the present study aimed to establish and compare the estimation performance of the quantitative parameters of the reconstruction methods filtered backprojection (FBP) and ordered-subset expectation maximization (OSEM). Methods: A beating-heart phantom with known values of end-diastolic volume, end-systolic volume, and LVEF was used. Quantitative gated SPECT/quantitative perfusion SPECT software was used to obtain these quantitative parameters in a semiautomatic mode. The Butterworth filter was used in FBP, with the cutoff frequencies between 0.2 and 0.8 cycles per pixel combined with the orders of 5, 10, 15, and 20. Sixty-three reconstructions were performed using 2, 4, 6, 8, 10, 12, and 16 OSEM subsets, combined with several iterations: 2, 4, 6, 8, 10, 12, 16, 32, and 64. Results: With FBP, the values of end-diastolic, end-systolic, and the stroke volumes rise as the cutoff frequency increases, whereas the value of LVEF diminishes. This same pattern is verified with the OSEM reconstruction. However, with OSEM there is a more precise estimation of the quantitative parameters, especially with the combinations 2 iterations × 10 subsets and 2 iterations × 12 subsets. Conclusion: The OSEM reconstruction presents better estimations of the quantitative parameters than does FBP. This study recommends the use of 2 iterations with 10 or 12 subsets for OSEM and a cutoff frequency of 0.5 cycles per pixel with the orders 5, 10, or 15 for FBP as the best estimations for the left ventricular volumes and ejection fraction quantification in myocardial perfusion scintigraphy.

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Introdução – Os estudos Gated – Single Photon Emission Computed Tomography (SPECT) são uma das técnicas de imagiologia cardíaca que mais evoluiu nas últimas décadas. Para a análise das imagens obtidas, a utilização de softwares de quantificação leva a um aumento da reprodutibilidade e exatidão das interpretações. O objetivo deste estudo consiste em avaliar, em estudos Gated-SPECT, a variabilidade intra e interoperador de parâmetros quantitativos de função e perfusão do miocárdio, obtidos com os softwares Quantitative Gated SPECT (QGS) e Quantitative Perfusion SPECT (QPS). Material e métodos – Recorreu-se a uma amostra não probabilística por conveniência de 52 pacientes, que realizaram estudos Gated-SPECT do miocárdio por razões clínicas e que integravam a base de dados da estação de processamento da Xeleris da ESTeSL. Os cinquenta e dois estudos foram divididos em dois grupos distintos: Grupo I (GI) de 17 pacientes com imagens com perfusão do miocárdio normal; Grupo II (GII) de 35 pacientes que apresentavam defeito de perfusão nas imagens Gated-SPECT. Todos os estudos foram processados 5 vezes por 4 operadores independentes (com experiência de 3 anos em Serviços de Medicina Nuclear com casuística média de 15 exames/semana de estudos Gated-SPECT). Para a avaliação da variabilidade intra e interoperador foi utilizado o teste estatístico de Friedman, considerando α=0,01. Resultados e discussão – Para todos os parâmetros avaliados, os respectivos valores de p não traduziram diferenças estatisticamente significativas (p>α). Assim, não foi verificada variabilidade intra ou interoperador significativa no processamento dos estudos Gated-SPECT do miocárdio. Conclusão – Os softwares QGS e QPS são reprodutíveis na quantificação dos parâmetros de função e perfusão avaliados, não existindo variabilidade introduzida pelo operador.

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Introdução – A tomografia de emissão de fotão simples sincronizada com o sinal eletrocardiográfico (Gated-SPECT) é essencial para a avaliação conjunta da perfusão e da função ventricular esquerda (VE) do miocárdio. Objetivo – Investigar a relação entre a função VE e o índice de captação (IC) miocárdio/pulmão direito (M/PD) e M/P esquerdo (M/PE) nos estudos Gated-SPECT com 99mTc-Tetrofosmina. Metodologia – Amostra de 32 pacientes que realizaram estudos Gated-SPECT por indicação clínica, sendo subdividida em dois grupos: Grupo I (GI) – pacientes com a informação clínica de enfarte agudo do miocárdio (EAM); Grupo II (GII) – pacientes com a informação clínica de isquemia. Por cada paciente adquiriram-se imagens estáticas torácico-abdominais e dois estudos Gated-SPECT do miocárdio (protocolo de um dia esforço/repouso). Nas imagens estáticas definiram-se regiões de interesse (Regions of interest – ROI) para calcular os IC. Nos estudos Gated-SPECT utilizou-se o software Quantitative Gated SPECT/Quantitative Perfusion SPECT para calcular a Fração de Ejeção do Ventrículo Esquerdo (FEVE). Efetuou-se análise estatística descritiva para caracterização da amostra. Aplicou-se o teste de Spearman para avaliar a correlação entre a FEVE e os IC por grupo de pacientes. O Teste de Willcoxon foi usado para comparar FEVE em repouso e em esforço. Resultados – Nos estudos Gated-SPECT em esforço não se verificou correlação estatisticamente significativa entre a FEVE e os IC, para GI e GII; em repouso existe correlação positiva estatisticamente significativa entre a FEVE e os IC, para GI; para GII não se verificou correlação. Na comparação dos valores de FEVE em esforço e repouso nos dois grupos constatou-se a existência de diferenças estatisticamente significativas, sendo a FEVE em EsforçoSPECT (GI e GII).

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A crucial method for investigating patients with coronary artery disease (CAD) is the calculation of the left ventricular ejection fraction (LVEF). It is, consequently, imperative to precisely estimate the value of LVEF--a process that can be done with myocardial perfusion scintigraphy. Therefore, the present study aimed to establish and compare the estimation performance of the quantitative parameters of the reconstruction methods filtered backprojection (FBP) and ordered-subset expectation maximization (OSEM). METHODS: A beating-heart phantom with known values of end-diastolic volume, end-systolic volume, and LVEF was used. Quantitative gated SPECT/quantitative perfusion SPECT software was used to obtain these quantitative parameters in a semiautomatic mode. The Butterworth filter was used in FBP, with the cutoff frequencies between 0.2 and 0.8 cycles per pixel combined with the orders of 5, 10, 15, and 20. Sixty-three reconstructions were performed using 2, 4, 6, 8, 10, 12, and 16 OSEM subsets, combined with several iterations: 2, 4, 6, 8, 10, 12, 16, 32, and 64. RESULTS: With FBP, the values of end-diastolic, end-systolic, and the stroke volumes rise as the cutoff frequency increases, whereas the value of LVEF diminishes. This same pattern is verified with the OSEM reconstruction. However, with OSEM there is a more precise estimation of the quantitative parameters, especially with the combinations 2 iterations × 10 subsets and 2 iterations × 12 subsets. CONCLUSION: The OSEM reconstruction presents better estimations of the quantitative parameters than does FBP. This study recommends the use of 2 iterations with 10 or 12 subsets for OSEM and a cutoff frequency of 0.5 cycles per pixel with the orders 5, 10, or 15 for FBP as the best estimations for the left ventricular volumes and ejection fraction quantification in myocardial perfusion scintigraphy.

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(99m)Tc-MIBI gated myocardial scintigraphy (GMS) evaluates myocyte integrity and perfusion, left ventricular (LV) dyssynchrony and function. Cardiac resynchronization therapy (CRT) may improve the clinical symptoms of heart failure (HF), but its benefits for LV function are less pronounced. We assessed whether changes in myocardial (99m)Tc-MIBI uptake after CRT are related to improvement in clinical symptoms, LV synchrony and performance, and whether GMS adds information for patient selection for CRT. A group of 30 patients with severe HF were prospectively studied before and 3 months after CRT. Variables analysed were HF functional class, QRS duration, LV ejection fraction (LVEF) by echocardiography, myocardial (99m)Tc-MIBI uptake, LV end-diastolic volume (EDV) and end-systolic volume (ESV), phase analysis LV dyssynchrony indices, and regional motion by GMS. After CRT, patients were divided into two groups according to improvement in LVEF: group 1 (12 patients) with increase in LVEF of 5 or more points, and group 2 (18 patients) without a significant increase. After CRT, both groups showed a significant improvement in HF functional class, reduced QRS width and increased septal wall (99m)Tc-MIBI uptake. Only group 1 showed favourable changes in EDV, ESV, LV dyssynchrony indices, and regional motion. Before CRT, EDV, and ESV were lower in group 1 than in group 2. Anterior and inferior wall (99m)Tc-MIBI uptakes were higher in group 1 than in group 2 (p < 0.05). EDV was the only independent predictor of an increase in LVEF (p=0.01). The optimal EDV cut-off point was 315 ml (sensitivity 89%, specificity 94%). The evaluation of EDV by GMS added information on patient selection for CRT. After CRT, LVEF increase occurred in hearts less dilated and with more normal (99m)Tc-MIBI uptake.

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As guidelines de cardiologia nuclear europeia e americanas não são específicas na escolha dos melhores parâmetros de reconstrução de imagem a utilizar na Cintigrafia de Perfusão do Miocárdio (CPM). Assim, o presente estudo teve como objectivo estabelecer e comparar o efeito dos parâmetros quantitativos dos métodos de reconstrução: Retroprojecção Filtrada (FBP) e Ordered ‑Sub‑set Expectation Maximization (OSEM). Métodos: Foi utilizado um fantoma cardíaco, cujos valores do volume telediastólico (VTD), volume telesistólico (VTS) e fracção de ejecção ventricular esquerda (FEVE) eram conhecidos. O software Quantitative Gated SPECT/Quantitative Perfusion SPECT foi utilizado em modo semi‑automático, a fim de obter esses parâmetros quantitativos. O filtro Butterworth foi usado no FBP com as frequências de corte entre 0,2 e 0,8 ciclos/pixel combinadas com as ordens de 5, 10, 15 e 20. Na reconstrução OSEM, foram utilizados os subconjuntos 2, 4, 6, 8, 10, 12 e 16, combinados com os números de iterações de 2, 4, 6, 8, 10, 12, 16, 32 e 64. Durante a reconstrução OSEM efectuou‑se uma outra reconstrução baseada no número de iterações equivalentes - Expectation‑Maximization (EM) 12, 14, 16, 18, 20, 22, 26, 28, 30 e 32. Resultados: Após a reconstrução com FBP verificou‑se que os valores de VTD e VTS aumentavam com o aumento da frequência de corte, enquanto o valor da FEVE diminui. Esse mesmo padrão é verificado na reconstrução OSEM. No entanto, com OSEM há uma estimativa mais precisa dos parâmetros quantitativos, especialmente com as combinações 2I × 10S e 12S × 2I. Conclusão: A reconstrução OSEM apresenta uma melhor estimativa dos parâmetros quantitativos e uma melhor qualidade de imagem do que a reconstrução com FBP. Este estudo recomenda o uso de 2 iterações com 10 ou 12 subconjuntos para a reconstrução OSEM e uma frequência de corte de 0,5 ciclos/pixel com as ordens 5, 10 ou 15 para a reconstrução com FBP como a melhor estimativa para a quantificação da FEVE através da CPM.

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Myocardial ischemia may occur during an exercise session in cardiac rehabilitation programs. However, it has not been established whether it is elicited when exercise prescription is based on heart rate corresponding to the anaerobic threshold as measured by cardiopulmonary exercise testing. Our objective was to determine the incidence of myocardial ischemia in cardiac rehabilitation programs according to myocardial perfusion SPECT in exercise programs based on the anaerobic threshold. Thirty-nine patients (35 men and 4 women) diagnosed with coronary artery disease by coronary angiography and stress technetium-99m-sestamibi gated SPECT associated with a baseline cardiopulmonary exercise test were assessed. Ages ranged from 45 to 75 years. A second cardiopulmonary exercise test determined training intensity at the anaerobic threshold. Repeat gated-SPECT was obtained after a third cardiopulmonary exercise test at the prescribed workload and heart rate. Myocardial perfusion images were analyzed using a score system of 6.4 at rest, 13.9 at peak stress, and 10.7 during the prescribed exercise (P < 0.05). The presence of myocardial ischemia during exercise was defined as a difference ≥2 between the summed stress score and summed rest score. Accordingly, 25 (64%) patients were classified as ischemic and 14 (36%) as nonischemic. MIBI-SPECT showed myocardial ischemia during exercise within the anaerobic threshold. The 64% prevalence of ischemia observed in the study should not be looked on as representative of the whole population of patients undergoing exercise programs. Changes in patient care and exercise programs were implemented as a result of our finding of ischemia during the prescribed exercise.

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El objetivo de la presente investigación consiste en describir las características de un asesino en serie colombiano desde la perspectiva psicodinámica. En este sentido, el abordaje teórico realizado en este trabajo se compone inicialmente de una concepción de asesinos en serie, posteriormente se hace una revisión acerca de las bases biológicas y los factores sociales del homicida serial, igualmente, se explican tres teorías psicodinámicas a trabajar (Sigmund Freud y Erick Erickson). Finalmente, se hace mención dentro de la investigación a la comparación casuística de los asesinos en serie, teniendo en cuenta a cuatro asesinos en serie mediante el abordaje psicodinámico. Por otra parte, a nivel metodológico, el tipo de estudio realizado es descriptivo con un corte cualitativo y un diseño no experimental, basado en la revisión de fuentes bibliográficas. Como producto se pretende hacer una aproximación al perfil correspondiente de la personalidad de un asesino en serie colombiano mediante las teorías psicodinámicas.

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El trasplante de órganos es considerado uno de los avances más significativos de la medicina moderna y es un procedimiento cada vez más exitoso en términos de supervivencia de los pacientes, siendo actualmente la mejor opción de tratamiento para los pacientes con innumerables patologías. El proceso de donación es insuficiente para cubrir las necesidades de trasplante de la población, por lo tanto, se hace necesario el desarrollo de nuevas estrategias para fortalecer la experiencia y efectividad de los programas existentes. La falta de conocimiento de los profesionales de la salud, su percepción y actitud hacia temas relacionados con el proceso de donación, pueden convertirlos en facilitadores o barreras para la identificación de potenciales donantes. Por esta razón, los recursos disponibles, las actitudes hacia la donación, la legislación y conocimiento de los procesos involucrados en la donación de tejidos y órganos son críticos. Dada la influencia de los profesionales de salud se definen los objetivos de este proyecto de tesis: determinar cuál es el conocimiento y las habilidades de los profesionales de la salud encargados de los trasplantes de órganos y de tejidos en la regional 1, evaluados mediante una herramienta educativa para contribuir a mejorar un programa eficiente de Donación de Órganos y tejidos y así mismo, fijar recomendaciones en aras de aumentar las tasas de donación, con especial énfasis en la actividad hospitalaria en el país. METODOLOGIA Se realizó un estudio basado en el análisis de la evaluación de conocimientos del proceso donación- trasplante de órganos y tejidos en el personal de salud participante en la herramienta educativa llamada “Curso taller primer respondiente del potencial donante de órganos y tejidos”. Este curso incluía un formato evaluativo que fue diligenciado de manera anónima por los participantes antes y después de recibir el contenido del curso. El estudio se desarrolló en personal de la Salud de IPS pertenecientes a la Regional I, de la Red Nacional de donación y trasplantes de órganos y tejidos. Con el fin de evidenciar si existen diferencias en el conocimiento de los participantes del curso antes y después de asistir al mismo, se utilizó la prueba de McNemar (p< 0.05). RESULTADOS Entre julio del 2011 y junio del 2012, se realizó el “Curso taller primer respondiente del potencial donante de órganos y tejidos” y se obtuvieron 303 encuestados incluidos médicos, enfermeras y auxiliares de enfermería. Al inicio del curso las respuestas acertadas con relación a legislación, selección del donante, muerte encefálica y mantenimiento del donante estuvieron alrededor del 50%. No fue posible detectar la profesión que pudiese generar riesgo en la detección del donante y los procesos asociados. Posterior al curso, el 72% de las preguntas se respondieron de manera correcta, lo que representa un incremento estadísticamente significativo. Este cambio evidenció significancia estadística al usar la prueba de McNemar y arrojar un valor de p=0.00. .DISCUSIÓN El personal de salud participante en el curso taller proveniente de unidades involucradas como generadoras de donantes muestra un déficit de conocimientos del proceso donación trasplantes lo que puede convertirlos en limitantes para dicho proceso