Montage using overlay and alphadata

Hello,

I am trying to generate a mosaic of images from a matrix, that is actually a superimposition of two images. I have succeeded when it's only one image by using alphadata, but I tried to do the same for montage and it didn't work. Is this the right way to do it, or is there another way?

montage(reshape(coronal,[size(coronal,1), size(coronal,2), 1, size(coronal,3)]), 'DisplayRange',[]); %%Montage of the image I want on the background
colormap(gray)
hold on
dec=montage(reshape(axial,[size(axial,1), size(axial,2), 1, size(axial,3)]), 'DisplayRange',[50 80]); %%Montage of the image from which I only want to have alphadata (zero values transparent)

colormap(hot)
set(dec, 'Alphadata', double(dec~=0))

Thank you