Definitive listing of Meta-data
See DICOM PS 3.3 (found at medical.nema.org )
A.32.8.1 VL Whole Slide Microscopy Image IOD Description
For a complete description of the international standard for encoding all of the information (including meta-data) that was considered relevant by those involved. Note that there are mechanisms identified within the standard for clinical trial information, anonymization (de-identification), and digital signatures.
The Patient Information Entity contains the patient identification.
Patient ID is not universally unique as defined by most clinical sites, so the cloud service provider would probably need to intervene in de-identifying prior to storage in the cloud with a mechanism for providing a secure re-identification method to the local clinician (and away from cloud storage).
Not sure why storage in the cloud would be so much better than local storage, and for images as big as they say, wouldn't upload bandwidth be an issue?
Machine learning part would certainly be facilitated by having centralized storage (and centralized processing... not sure the clinicians want to foot the bill for the machine learning).