I don't think we need to scan 100% of the brain in molecular detail in order to read & preserve the information. It should be possible to observe the circuitry at a higher level and recreate an approximation -- though it'd be just that, an approximation. Additionally, much of the information could be compressed to a much more lightweight format than digitizing the physical neural networks of the brain.

Digitizing a static physical model of the brain is problematic in itself. Many regions and structures in the brain are likely structurally dynamic. That is, the neural circuitry could change structure from day to day and this is definitely true over longer timescales. So it'd be much easier to read the data from the brain into another format rather than emulate the physical structure of the hardware.

I've thought a bit about information could be read from MRI scans such as these. In the absence of higher resolution data, I don't think there could any memories retrieved. I don't know the low-level details of how MRI data is encoded, but I do know it is recorded in slices. To retrieve memories, you'd need to read 3D regions from the brain. And it'd need to be much more high-resolution.