Hello again,
Yes, they are DICOM images.
Yes, I can upload single image files. But it would be very time consuming to upload all of the images from an MRI study one at a time.
The functionality of the directory upload feature does not allow you to select a zip file to upload. It asks you to select a directory, which it will then zip for you for upload. But it does not work.
I did not understand much of what was written about php dependencies and MIME whitelisting in the thread you mentioned. I do not know how to check whether I have php_fileinfo installed and enabled. In Admin->System->Files I have no whitelist or blacklist.
I cannot find any thread corresponding to this issue in the forum search.