Check if a cropped version exists

Hi

I love the JS Crop but would only like to use it for creating crop versions manually - I do not want to have a crop version generated automatically.
I would like to use the standard image module version of an image in the template but if there is a crop version created (by an editor) then the template should use that version.

Is there any nice way to check if there is a crop version created for that image before calling the imagecache theme function?

thank you
Vas