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Abstract #1338

Optimal Bipolar Gradient Design to Reduce Velocity Offsets.

Marijn P. Rolf1, Mark B.M. Hofman1, Peter D. Gatehouse2, Albert C. van Rossum3, Rob M. Heethaar1

1Physics and Medical Technology, ICaR-VU, VU University Medical Center, Amsterdam, Netherlands; 2Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, London, United Kingdom; 3Department of Cardiology, ICaR-VU, VU University Medical Center, Amsterdam, Netherlands

Uncompensated eddy-currents cause velocity offsets, resulting in significant errors in clinical flow quantification. To reduce these offsets, the influence of velocity encoding gradient settings was studied in detail. Specifically the bipolar gradient timing, velocity encoding strategy (asymmetric or symmetric), and gradient amplitude and slew rate were studied. Timing showed no correlation with offset. Symmetrical encoding resulted in significantly lower offsets. Velocity offsets were also reduced by lowering the gradient amplitude and slew rate, however those protocols are not always compatible with the time-constraints of breath-hold imaging.