Can anyone identify where this pic is from?
 

I had a TMNT shirt as a kid that I remembered really liking, but having kind of a fuzzy recollection of, and I recently stumbled across a pic of myself wearing it, unfortunately it's super small and you can only see a sliver of the shirt, but at least it's a starting point. If it helps to narrow down the search, this photo would've been taken in 1990, I believe.

Anyone have any idea where this art was originally used, can you identify the shot it's from? I was thinking it looks similar in style to Dan Berger's TMNT group shot 2 page spread from vol 1 #45, but it's not that. Any help is appreciated!

Looks like it might simply be some original art design made specifically for T-shirts. As you said, there's a good chance it's based on work by Dan Berger. Perhaps you could message him on Facebook and see if he has any knowledge of the design.