[hashmymustache]

I'm not sure what you mean by movement of blood induces currents. The magnetic gradients are what induce current in the body, but usually more peripherally where the gradients are steepest and in big nerve bundles like sciatic.

When I would put humans in our 7T machine they'd sometimes feel their leg kicking during the acquisition. Because it's actively shielded with a pretty steep magnetic field from 0 to 7T you have to advance them into the scanner very slowly otherwise they can become very uncomfortable and nauseous.

[phkahler]

>> I'm not sure what you mean by movement of blood induces currents.

Blood is a conductive fluid. When you move a conductor through a magnetic field there is an electric current induced.

[cma]

what about rotating a ring on its axis of symmetry? Blood is in a loop, though not perfectly smooth and unchanging flow, as valves and stuff are squeezing at different time.