calculate the volume of tumor in logical image

To Compute the no. of voxel (==1) in logical/binary .mat file

%load your binary/logical image
load(logical.mat)%just example
Voxels = sum(labels(:)==1)
VoxelVol = sum((labels==1).*dV,'all');
%If you have varying size of the voxels, for example if the voxels in the first and last slices are larger than the ones in the centre, then you have to take that into account. For example if the size varies as:
[x,y,z] = meshgrid(1:130,1:130,1:36);
dV = 1 + 4/36^2*(z-18.5).^2;
% To just extract the tumor-flagged voxels from your imstack3-variable you can do just this:
Tumor_vals = imstack3(labels(:));
%If you need to find the location/indices of the tumors you can do:
[idx1] = find(labels(:));                                     
[i1,i2,i3] = ind2sub(size(labels),idx1);
slice(double(imstack3),63,60,7),shading flat                
hold on
plot3(i2,i1,i3,'r.')