Fig. 2
From: Cardiovascular magnetic resonance phase contrast imaging
Difficulty where wraparound is not an “island” in the flow: a Peak flow through a mildly narrowed pulmonary vein showing velocity aliasing of black into white (arrow) at VENC 80 cm/s. b Unwrapping this aliasing was uncertain in partial-volume pixels neighboring the reverse flow channel (arrow) offset 50 cm/s. c The same plane acquired at VENC 130 cm/s showed true forward flow in black and the reverse flow channel at its left on the image. (provided by Dr. Sylvia Chen, Royal Brompton Hospital, London, UK)