Is there a way to use Dynamic URLs in images for Email Treatments?

The standard way to include a Dynamic URL in an Email Treatment for an Email Mkt Campaign is by creating a name/url pair in the appropriate link bar and then embedding it in the template - thus creating a <href> tag with text and a link.

However, we were trying to use an image instead of text, but the bookshelf doesn't offer any solutions.

Anyone ever tried to do this?

Thanks

Luis