Tecnically, with only one single 2D image, you cannot obtain a tridimensional image.
As you might know, a 2D image has [x, y] dimensions. You can see it by calling
The z dimension (that represents real data) come from a volumetric (3D) image.
128 128 256
if you pick
So the way around is possible: to get a 2D image out of a stack of slices in a 3D-image volume.
YOU CAN make a stack of your png 2D images. But it would not make sense, as it will be a stack of repeated images.
yourStack(:, :, 1) = yourPNGfile;
yourStack(:, :, 2) = yourPNGfile;