<img src="//pages.example.com/images/{{Lead.HeadshotImage}}">
Hi Samantha,
You could create a segmentation with 28 possible values (default). Then you could create a signature snippet that is segmented on this Account Manager segment. Each segment would then have the account manager's information and image.
You can then add this snippet to an email by replacing (right click, replace with snippet) a block with a snippet.
Depending on the segment you belong to (who your Account Manager is) you would receive a different image.