[Plugin: Media Credit] Credits for automatically included pictures

We are using a Theme which allows us to declare categories as “featured categories” which are presented in a nice way on the index.php. Therefore the author has to upload an picture separately via an additional field. Of course this can also be loaded from the Media Library where the Media Credits are defined. This special picture, being not directly in the content of each article would usually not appear on each single article page but I edited the single.php and told WordPress to get this image automatically.

But how do I get the Credits of this picture?

http://wordpress.org/extend/plugins/media-credit/