• Franck Lamberton, Nicolas Delcroix, Denis Grenier, Bernard Mazoyer, and Marc Joliot.
• Unité Mixte de Recherche (UMR)6194 Centre National de Recherche Scientifique (CNRS), Commissariat à l'Energie Atomique (CEA), Université de Caen et Paris 5, Caen, France.
• J Magn Reson Imaging. 2007 Sep 1; 26 (3): 747-55.

PurposeTo retrospectively correct for geometrical distortions, a new dynamic field mapping method suitable for dynamic single-shot gradient-echo type echo-planar imaging (GRE-EPI) is proposed.Materials And MethodsThe method requires a single volume additional acquisition and allows the extraction of a field map from each phase volume, assuming invariance across time of the echo time-independent phase component. Performances of the method are assessed using three sets of experiments: the first tests the prerequisite and the modeling; the second tests the method with time-dependent geometrical distortions; and the third presents a comparison with two other methods.ResultsOur results legitimize the modeling procedure and demonstrate that the dynamic method is less sensitive to noise than the other methods. A theoretical explanation for this is proposed in the discussion section.ConclusionGiven the minor increase in the acquisition time, this method is well suited for functional magnetic resonance imaging; prospective direction.(c) 2007 Wiley-Liss, Inc.

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