How to Calculate a Hash of a file that is 1 Terabyte and over?

Question

So, I have a couple of system backup image files that are around 1 terabyte, and i want to calculate fast the hash of each one of them (preferably SHA-1).

At first i tried to calculate the md5 hash, 2 hours had passed and the hash hadn't been calculated yet (something that's obvious for large files up to 1TB).

So is there any program/implementation out there that can hash a 1TB file quickly?

I have heard of Tree-Hashing that hashes parts of file simultaneously, but I haven't found any implementation so far.