It's not easy, but doable. If you want to located all the regular pages that has a image embedded as content, you would do a SQL search for the file name against CMS_DocumentTable > DocumentContent column.
But if you have other page types that has a media select field that editor could select an image, you will have to search against those custom table for each page type as well.
You can create a custom report using Reporting application for editor to search, but the SQL script can be complex depending on what kind page you want to search.