SQL & PL/SQL :: Check Every Table For Data?

I'm working on a feature that needs to check every table for data. At the moment I am roundtripping every time and running the query like this:

SELECT 1 FROM dual WHERE EXISTS(SELECT 'x' FROM table_name)

Is there a better way that allows me to get the result for all tables in one trip? I've tried a correlated subquery like this:

SELECT table_name, (SELECT 1 FROM dual WHERE EXISTS(SELECT 'x' FROM table_name) FROM all_tables

but I think that doesn't work because Oracle looks for a table called table_name rather than the value from the outer query.