[superkuh]

>need field homogeneity (and/or accurate mapping), high quality gradients

It always confused me that MRI did millimeter scale imaging with radio waves that are meters long. I learned, and other's might be interested to learn, the trick is that it's the magnetic gradient that does the imaging. Each nucleus in the volume is tagged to it's place along the magnetic gradient axis by the local magnetic field strength shifting the emission frequency proportionally. That frequency shift is then inverted back to position for that axis.

[ska]

Good point. It’s easy to forget this stuff isn’t obvious.