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Hello, You can obtain ROIs from the resulting TBSS statistical map using a clustering algorithm like k-means...This algorithm is implemented in the Matlab software...The output is a set of non-overlapping k clusters in which each voxel belongs to the cluster (or ROI) with the nearest mean. If you need n ROIs, you can select k>n, and then choose the n cluster "more representative" of your map... For more details see http://en.wikipedia.org/wiki/K-means_algorithm Regards, Erick J. Canales-Rodríguez (+34) 93 652 99 99 ext. 255 Unitat de Recerca, Benito Menni CASM (http://www.hospitalbenitomenni.org/Default.aspx) Sant Boi del Llobregat (Barcelona), Espanya/España/Spain Benito Menni Complex assistencial en Salut Mental ________________________________________ De: FSL - FMRIB's Software Library [[log in to unmask]] En nombre de Ruchika Wadhwa [[log in to unmask]] Enviado el: viernes, 10 de abril de 2009 0:50 Para: [log in to unmask] Asunto: [FSL] making ROI's for DTI data Hello: I have been analyzing the 12 direction DTI data with patients and controls using TBSS. I used tfce for my final statistical analyses and get predicted results in the controls>patients contrast. However, when I use the cluster command to parse out the possible clusters in my data, from which I could pull out the mean FA values, I get this one big cluster that pretty much encompasses the entire contrast with some other clusters. The way I understand is that cluster works by combining all the areas with a similar p-value? Given that this cluster includes the genu of the CC, splenium and the posterior thalamic radiation amongst many others, it kind of defeats the purpose of pulling out mean FA from more defined clusters. Is there any other way that I can accomplish this? One way I was thinking of doing this would be to take the local maxima in the clusters and creating an ROI around that. But I was wondering what approach do people usually follow for making an ROI for DTI data? Is it just mostly creating a 10 mm box around the peak voxel? Any help would be much appreciated. Sincerely, -Ruchika Este mensaje se dirige exclusivamente a su destinatario y puede contener información privilegiada o confidencial. Si no es vd. el destinatario indicado, queda notificado de que la utilización, divulgación y/o copia sin autorización está prohibida en virtud de la legislación vigente. Si ha recibido este mensaje por error, le rogamos que nos lo comunique inmediatamente por esta misma vía y proceda a su destrucción. Aquest missatge va dirigit exclusivament al seu destinatari i pot contenir informació privilegiada o confidencial. Si vosté no és el destinatari indicat, li notifiquem que la utilització, divulgació i/o còpia sense autorització està prohibida en virtud de la legislació vigent. Si ha rebut aquest missatge per error, li preguem que ens ho comuniqui el més aviat possible.