Dark flow artifacts with steady-state free precession cine MR technique: causes and implications for cardiac MR imaging.

Steady-state free precession cine images from cardiac magnetic resonance imaging studies of 24 patients were reviewed retrospectively to identify dark flow artifacts. The cause and features of the artifacts were studied in flow phantom experiments. Dark flow artifacts were recognized in eight of the 24 cases and were characterized by low or inhomogeneous signal intensity in blood pools with little change in adjacent tissues. The artifacts could be mimicked in flow phantom experiments by deliberately deshimming the gradients and appeared periodically during imaging with off-centered frequencies. These artifacts appeared to be caused by spins moving within an inhomogeneous magnetic field.