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Abstract #4628

Optimisation of Velocity Encoding Gradients for Phase Contrast Gas Velocity Taking Diffusion Into Account.

Lionel Martin1, Xavier Matre1, Mathieu Sarracanie1, Marlies Friese2, Ludovic de Rochefort1, Rose-Marie Dubuisson1, Emeline Boriasse1, Emmanuel Durand1

1Imagerie par Rsonance Magntique Mdicale et MultiModalits (UMR8081), Univ Paris-Sud, CNRS, Orsay, France; 2Center for Magnetic Resonance, The University of Queensland, Brisbane, Queensland, Australia

MR flow measurement techniques have mostly been used in liquids. For coherent motion (flow), bipolar gradients induce a phase shift and a signal drop for incoherent motion (diffusion). This effect, negligible for liquids, cannot be neglected for gases. Competition between these two phenomena results in the existence of an optimal FOS that could be theoretically determined. 2D velocity maps of parabolic flows were acquired with different FOS and gases. Results show that velocity error is a function of the FOS and a different optimal FOS is reached for each gas. Thus, they validate our theoretical simulations.