Hi Rick,

Thank you for your reply.

Yes, for now, I am segmenting those lesions using the same kind of idea you are talking about. In fact, I use the FLAIR image for the underlay. Then, I open Draw Dataset plugin and "choose the data set to copy". Then, I force the overlay to be my FLAIR image. Now, when I adjust the threshold appropriately to each lesion i am interested and I outline exactly the colored cluster lesion. In this case, I cannot see right away the result of my ROI but it still work and I don't mind too much.

With a few lesion it's ok. However, if you have a lot of lesions, it would be nice to roughly circle the lesion (in fact, defined by being brighter than the close surrounding area) and the plugin would automatically multiply this ROI by a mask of the FLAIR image at the chosen threshold.

It is just a way of quickly picking clusters of pixels resulting from thresholding. I think, it could be a general tool. ... but i know it seems complex to modify Draw Dataset for that, so for now I continue with the more manual technique. I 'll try sometime, when I have time.

Julien