If you can insert references, not actual copies, of your image files from that server, then you can use Insert Records | Folder to populate a table of images from that file without importing actual copies of the file, just the filepaths to those files. A field in this table can receive the file name as part of the import so you can use that to link these records to your parts table. If there is no related record, there is no part image in your folder on the server. But if you later remove a image file from the folder, you would not get an automatic update to tell you that the image file is no longer there.
You can also use a web viewer to access and display those files. I think that combining a web viewer with GetLayoutObjectAttribute, would allow you to confirm whether or not an image file exists in that folder.
There are also plugins that can list the file names of all files present in a folder, so you might be able to use that approach to determine which parts do and do not have associated image files.