Nice pose. :) Did you increase exposure during conversion? My best guess that the noise in the dark areas is a result of just that. The pose is fab, but I already said that. :) TFS....
According to Arties guide to the MKIV, you should disable the NR function, I do.
I only just noticed your high ISO so this may go someway to explain it, I am alsoreliably informed by Sabyaschi that you should never use intermediate ISO as these are a lot noisier. Stick to 200, 400, 800, 1600 I have not yet tried 3200 but I have seen images at this level with reasonable noise.