Flow effects in long-range dipolar field MRI.
Incoherent spin motion, such as diffusion, can lead to significant signal loss in multiple spin echoes (MSE) experiments, sometimes to its complete extinction. Coherent spin motion, such as laminar flow, can also modify the magnetization in MSE imaging and yield additional contrast. Our experimental results indicate that MSE is flow-sensitive. Our theoretical analysis and experimental results show how the effect of the distant dipolar field can be annihilated by flow. This effect can be quantified by directly solving the nonlinear Bloch equation, taking into account the deformation of the dipolar field by motion. Unexpected results have been observed, such as a recovery of the dipolar interaction due to flow in the "magic angle" condition.
Loureiro de Sousa
Paulo
P
Institut de Physique Biologique, Université Louis Pasteur, UMR 7004-CNRS, 4, rue Kirschléger, Strasbourg Cedex 67085, France. loureiro@ipb.u-strasbg.fr
Gounot
Daniel
D
Grucker
Daniel
D