How did Itachi use izanami??

[Ovan]

I don't think that is right.

 

[bdm]

Izanami doesnt require senju dna.
And lets assume u r correct then my ans will be

itachi was an edo while using izanami.and kabuto gave the dna of hashirama to edos and to his army.

 

[adeshina365]

Izanami doesn't require Senju DNA.

Its as simple as that.

 

[Senju Bean]

So if Izanagi was that wide spread such that it Izanami needed to be created, that means there must have been plenty of Uchiha with Senju DNA.