-MRIcron is actually excellent for extracting the VOI and displaying 2D images in a single plane or as orthogonal triplane images. I have found these steps helpful if you choose MRIcron:

• First, create an intensity filter of the perfusion image from the Draw menu. This will allow you to "extract" the volume of the hyper (or hypo) perfusion clusters.
• Then mask the clusters in the perfusion image using the Draw menu. Open the image of the clusters, then open the intensity filter voi as a VOI in the Draw menu, then apply the mask and save the result.
• Finally open the masked perfusion cluster as an overlay on your T1. I favor the actc LUT/color map to show these results

-BIS representations in the ISAS analysis are really nice too