Correction of vibration artifacts in DTI using phase-encoding reversal (COVIPER).
Bottom Line: We refined the model of vibration-induced echo shifts, showing that asymmetric k-space coverage in widely used Partial Fourier acquisitions results in locally differing signal loss in images acquired with reversed phase encoding direction (blip-up/blip-down).COVIPER was validated against low vibration reference data, resulting in an error reduction of about 72% in fractional anisotropy maps.COVIPER can be combined with other corrections based on phase encoding reversal, providing a comprehensive correction for eddy currents, susceptibility-related distortions and vibration artifact reduction.
Affiliation: Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, University College London, United Kingdom. firstname.lastname@example.orgShow MeSH
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Mentions: Motion during the diffusion-weighting period may shift the echo center towards the edge of k-space in PE direction (Fig 1) and lead to loss of the DW signal, as has been demonstrated for linear rigid-body motion (45). For linear rigid-body motion the shift of the echo center Δk only depends on rotational but not on the translational movement (45, 46):1 where γ is the gyromagnetic ratio, Ω is the angular velocity vector, a dimensionless unit vector in the diffusion gradient direction and m1 is the first moment of the gradient. Note that the first order gradient moment depends on the gradient waveform and thus might vary between diffusion sequences (see e.g., Ref.47).
Affiliation: Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, University College London, United Kingdom. email@example.com