query to find stories without acceptance test?

We originally didn't do a great job of writing down acceptance tests in the stories, most of them are currently blank. We'd like to remediate that. Instead of manually opening each story to see if it has acceptance test text, I'd like to configure a work item query to do that so I can edit the items in the list and populate that field until that query returns an empty list.

However, Acceptance Test is a full text field. When building a query, adding a condition using for the Acceptance Test attribute displays the message "Use the Full Text attribute if you would like to query this attribute's contents" with no controls. If a add a condition using the Full Text attribute, it seems to do a full text on the entire work item, not just the Acceptance Test attribute. And it does only a "contains", not "doesn't contain".

So are there any recommendations on the best way to achieve this? I'm on RTC 2.0.0.2. Thanks!