There are several ways to skin this cat, but below are a couple options for using an image, in lieu of text, as a link to content. There are other overloads for the Url.Action and the Html.ActionLink, but in this example I was linking to a different controller passing in the integer id of the item to display a list of child records. The "STEPS” image is displayed if the parent record has child records.
Note that the first parameter in the action link is a space (because I didn’t want any text to show over the button background image) and the first argument cannot be null or empty.
In the site CSS layout I added the following steps-button class that adds the image to the link as a background image.