Assessment of Position Dependent Eddy Current Distortions in DW EPI Measurements: Monopolar Versus Bipolar Diffusion Preparation

Verena Ballweg¹, Petros Martirosian¹, Hansjrg Graf¹, Hanne Wojtczyk¹, Fritz Schick¹

Eddy currents in DW EPI sequences cause distortions which negatively influence fibre tracking for instance. Bipolar gradients reduce those distortions but lead to a longer echo time and hence to a decreased signal-to-noise ratio. However, lately gradient system quality concerning eddy currents increased making bipolar sequences maybe needless. Therefore, the distortions of DW EPI sequences with monopolar and bipolar diffusion preparations were compared at off-center positions and in the isocenter, revealing that monopolar sequences can be applied in the isocenter without considerably greater distortions. At off-center positions bp gradients are still needed.