How to check if content has been modified

Hello,

We are updating our CTD table in the mgmt db externally. I am using the vgncontentscan utility to update the content instances. To do this, we need to write a content update checker class implementing IContentUpdateChecker. The concept itself seems simple. However, I can't figure out how to tell if a content item has been updated or not. I can see it working if we are able to compare table data in the mgmt side with the data on the delivery side. Is this possible with IContentUpdateChecker? I really hope that whoever designed this utility, class had in mind ways we can determine if any content has been updated. Right now I see no way to do this via mgmt server alone.

I do know there is an isModified field in vgnAsMoMetaData, but I don't think this gets triggered unless someone manually updates the content item via CMS. Simply updating a field in CTD table doesn't update this field in the vgnAsMoMetaData.