This is cool - for Metal, the debugging tools are pretty useful in Xcode - you can access buffers and read values directly.
Related - a while I made a process to convert DICOM / MRI files to voxels for printing at the native resolution of 3D printers [0]. It means you can preserve all the fine detail of the scans, rather than converting to a mesh (segmentation).
On the CD question - it's probably because there is little incentive to build a secure / cross platform solution for patients to access their scans. The CD model is very outdated, but does work, and there is no need for HIPAA compliance even though a CD isn't very secure.