The VOI will be used to quantify lung aeration in that slice. It seem there is no easy way to separate soft tissue from atelectasis in the dorsal regions of our image sets. The difference between inter-operator VOI sizes (in pixels) seems important in our study.
We are also interested in other DICOM Analysis Software up to the task.
Either OsiriX or MIPAV will do this operation well and easily. OsiriX is limited to the Mac platform only. MIPAV is a java application that can run on MS Windows, Mac OSX or Unix / Linux varieties. Both are free for research purposes. And both are supported. The display and toolset tend to be a bit better integrated in OsiriX. It is much easier to add new functions and programable macros in MIPAV. If you are only working on a Mac platform then OsiriX would be my choice as it's a bit easier to teach and perform these simple VOI operations. If you need to run on a variety of computer platforms then I recommend choosing MIPAV as it has that capability. It's not that much harder to learn that OsiriX and can just as well perform the VOI analysis.
I've not mentioned MALUNA so far as I've not experience with the program. Just perusing the users manual for version 3.14 it appears to be able to perform the VOI analysis also.
Thank you for your answer. We'll give MIPAV and/or OsiriX a try before trying MALUNA.
We aim to find out which application (OsiriX or MIPAV) and VOI selection tool gives us less inter-operator variability with the best discrimination of soft-tissue and atelectasis.
After analyzing different tools we are going to study MIPAV's Livewire and Polygon tools for selecting our VOIs. And see what's the interoperator variability in the different parameters available through the VOI Statistics Generators. I'll keep you posted. Thanks for your interest.