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Full list of author information is available at the end of the articleBackground Phase-contrast velocity mapping is applied to blood flow [1] and myocardial velocity mapping [2] in cardiovascular magnetic resonance (CMR). Velocity images are formed by subtracting the phase images of two acquisitions with differing velocity sensitivity. As is well known, other phase differences between the two images cause stationary tissue to display an apparent non-zero velocity, known as the background offset or baseline error. This may vary gra-dually with position over the velocity image and underlies stationary and moving tissues. Maxwell (or concomitant) gradient effects are one cause which can be corrected ana-lytically [3]. Eddy currents are another cause, and these are corrected to a large extent by actively-shielded gra-dient coils and pre-emphasis [4,5] although this is compli