Hi There,

I am trying to combine ROI masks and I am having a bit of trouble. I would like to add the ROI masks in such a way that I can see where both masks are active without having separate clusters for each ROI mask.

I tried the following calc command which did not give me a sum of the ROIs:
3dcalc -a 'func+orig[12]' -b 'func+orig[15]' -c 'func+orig[18]' \
-expr 'step(a-4.2)*step(b-2.9)*step(c-3.1)' \
-prefix compound_mask

Then I tried the following in 3dcalc to look all ROI A and ROI B active:
0 = none active 1 = A only active 2 = B only active
3 = A and B only 4 = C only active 5 = A and C only
6 = B and C only 7 = all A, B, and C active

3dcalc -a 'func+orig[12]' -b 'func+orig[15]' -c 'func+orig[18]' \
-expr 'step(a-4.2)+2*step(b-2.9)+4*step(c-3.1)' \
-prefix mask_8

The result was separate clusters for the individual ROIs even though they were shown on the same mask. Want I want to do is to have all regions active on the same mask but also fused into the same cluster.

Is there another function I can use to sum these ROIs so that I am getting all ROIs on the same mask but also fused into the same cluster?

Thanks,
Jayna