12/20/2023 0 Comments Medinria tractography dti![]() ![]() 6 These researchers found that tract volume measurements varied when different diffusion gradients were applied. These changes may affect the measurements of results employing tractography, as indicated by Fischer et al. 4 Variations can also be found in multicentre studies due to use of different MRI units and different protocols for the capture of DTI images. This may be due to the algorithms they employ or the manageability of the program itself, since reproducibility of results depends to a certain extent on how the user interacts with the software. ![]() 3 Although many different computer programs for performing tractography are available, and some may be freely used for research purposes, the results they deliver may vary from program to program. 2 Nevertheless, the technique has to be validated so that results will be reproducible and usable in quantitative analysis, and so that they reflect real anatomical details. This is currently the only non-invasive technique that can be used to view brain nerve tracts in vivo. 1 Brain tractography uses DTI images to reconstruct white-matter connections in the brain and model them in 3D. Los índices de FA y MD podrían ser indicadores tempranos de la enfermedad de Alzheimer, siendo necesario considerar el equipo y el método de adquisición de imágenes ya que pueden influir en los resultados como se comprobó en la comparación entre los 2 conjuntos de datos empleados.ĭiffusion-tensor imaging (DTI) is a special magnetic resonance (MR) imaging technique based on the diffusion of water in biological tissues. Se estableció una metodología reproducible para realizar tractografía en los fascículos estudiados. Existieron diferencias significativas en la comparación entre los datos de la base de datos y los del centro de investigación. Los pacientes con enfermedad de Alzheimer mostraron menores valores de FA y mayores valores de MD para el fascículo uncinado derecho correspondiente al centro de investigación. ResultadosĮn el estudio de reproducibilidad se obtuvieron coeficientes de correlación intraclase superior a 0,9 para las medidas de FA y MD del fascículo uncinado, y mayor de 0,68 para las del fascículo cingulado posterior. Dos observadores realizaron las mediciones 2 veces para evaluar la reproducibilidad intra- e interobservador. Se realizaron mediciones de anisotropía fraccional (FA) y difusividad media (MD) en el fascículo uncinado y el fascículo cingulado posterior, en imágenes obtenidas de una base de datos y de un centro de investigación, en 52 sujetos distribuidos en los 3 grupos de interés. En este trabajo de investigación se realizó un estudio cuantitativo por tractografía cerebral mediante imágenes de resonancia magnética potenciadas en difusión en pacientes con deterioro cognitivo leve, enfermedad de Alzheimer y controles normales, con el fin de analizar la reproducibilidad y validez de los resultados. La tractografía cerebral es una técnica que permite visualizar los fascículos de sustancia blanca que conectan distintas partes del cerebro y realizar estudios cuantitativos de diversa índole sobre ellos. The type of equipment and the method used to acquire images must be considered because they may alter results as shown by comparing the 2 data sets in this study. FA and MD indexes may serve as early indicators of AD. We established a reproducible methodology for performing tractography of the tracts in question. A comparison of the measurements from the 2 centres revealed significant differences. Patients with AD showed lower values of FA and higher MD values in the right UNC in images from the research centre. Measurements of FA and MD of the UNC delivered an intraclass correlation coefficient above 0.9 ICC was above 0.68 for the PCF. Two observers took the measurements twice in order to evaluate intra- and inter-observer reproducibility. Subjects and methodsįractional anisotropy (FA) and mean diffusivity (MD) were measured across the uncinate fasciculus (UNC) and the posterior cingulate fasciculus (PCF) in images, obtained from a database and a research centre, representing 52 subjects distributed among the 3 study groups. We completed a quantitative study using brain tractography with diffusion tensor imaging in patients with mild cognitive impairment, patients with Alzheimer disease (AD), and normal controls, in order to analyse the reproducibility and validity of the results. Brain tractography is a non-invasive medical imaging technique which enables in vivo visualisation and various types of quantitative studies of white matter fibre tracts connecting different parts of the brain. ![]()
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