Agreed - if you got it from a legitimate source (Technet, MSDN, or the Microsoft Store) you should have the ability to compare the ISO you downloaded against the hashes available on those sites (CRC, SHA1, MD5 sums, etc) to verify if what you downloaded is valid and matches the ISO on the source.
If you downloaded it from anywhere else, be aware that doing so is actually a violation of copyright laws in the US, Canada, and most (not all, but most) European countries.