Patent ID: 8779771

Claim:
A magnetic resonance marking system for marking a flowing medium in a marking region, comprising: a radio-frequency device that generates marking radio-frequency electrical signals; a marking radio-frequency transmission coil, supplied with said marking radio-frequency electrical signals, that radiates a marking radio-frequency field in the marking region corresponding to the marking radio-frequency electrical signals, the marking radio-frequency field interacting with nuclear spins of the flowing medium to mark the nuclear spins of the flowing medium by arterial spin labeling; a magnetic field determination device that determines a magnetic field strength that exists in said marking region during said radiation of said radio-frequency field; and a control unit configured to derive a marking transmission frequency from a known relation thereof to the magnetic fields strength determined by said magnetic field determination device, and to control the radio-frequency device to generate said marking radio-frequency electrical signals so as to cause the marking radio-frequency field, emitted by the marking radio-frequency transmission coil to be radiated at the derived marking transmission frequency.