An integrated approach to correction for off-resonance effects and subject movement in diffusion MR imaging

Abstract

In this paper we describe a method for retrospective estimation and correction of eddy current (EC)-induced distortions and subject movement in diffusion imaging. In addition a susceptibility-induced field can be supplied and will be incorporated into the calculations in a way that accurately reflects that the two fields (susceptibility- and EC-induced) behave differently in the presence of subject movement. The method is based on registering the individual volumes to a model free prediction of what each volume should look like, thereby enabling its use on high b-value data where the contrast is vastly different in different volumes. In addition we show that the linear EC-model commonly used is insufficient for the data used in the present paper (high spatial and angular resolution data acquired with Stejskal–Tanner gradients on a 3 T Siemens Verio, a 3 T Siemens Connectome Skyra or a 7 T Siemens Magnetome scanner) and that a higher order model performs significantly better.

The method is already in extensive practical use and is used by four major projects (the WU-UMinn HCP, the MGH HCP, the UK Biobank and the Whitehall studies) to correct for distortions and subject movement.

Highlights

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  We present a new method for correction of eddy current-induced distortions and subject movement in diffusion data.

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  It is based on alignment to predictions based on a Gaussian process

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  The results indicate that one can achieve reliable corrections even for high b-value data ( b = 7000).

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  A comparison to correlation ratio based registration (eddy_correct) indicates that the new method is vastly superior.