This is how the sub said he reported it and he eventually got a reply back from Twitter saying they had taken the profile down.

"Go to offending profile, choose “They’re pretending to be me or someone else”, then enter the actual user they are impersonating. Enough do that and it should work eventually."

However, I had others say the process wouldn't allow them to put my twitter handle in as the actual user being impersonated. Plus, I don't know if that will work for just photos. You can report individual tweets that contain your image but again, I'm not sure how responsive Twitter will be. Good Luck!