Is it possible to efficiently search for all mail with inline images using EWS?

It is easy enough to search for mails that have 'real' attachments.

And I can iterate through all emails and test each for html body, and if html, check for isinline in the attachment collection.

But I would rather like to reduce the number of emails returned from an EWS mail item Search to just those that have inline images.  Is this possible?

I am struggling to find what properties I can effectively use in a search.  Is there a way to obtain the complete set of attributes/properties that can be used in a search expression?

And there are different ways to perform searches as well
  AQS Search String [only limited search fields?]
vs SearchFilter.IsEqualTo([?BodyType?], [?is html type?])

so confusing!

Merlin Beedell