Averaging label maps

Operating system: OS
Slicer version: 4.6.2 r25516

Hello
I am doing volumetric segmentation of lesions in a series of patients (N=7). I have segmented each lesion into 3 regions of interest (which are arranged concentrically around each other) in each patient. I am interested in averaging these labels across the series in order to create an averaged representation of the volume and arrangement of these regions across the population.

Is there any way to do this? I would imagine I would have to define fiducials for each label map. Then import each of the label maps into a new scene and then register them to one another. Once/if I can do that, is there a way to create and averaged label map taking all these volumes into account?

Thanks!
Maya

You can compute distance map )Simple Filters module, SignedMaurerDistanceMapImageFilterÖ, average the distance maps, and threshold the result.