I made a build with only one file(5KB) added in UltraISO and have the same file size as before!!!! After the save, the image went from 4,3GB to 4,57 GB!!! I just added one file in UltraIso(Eng.LSC) and saved the file.
I will try to use MagicISO as described by Malaspina. Let you know the result in a few moments...