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
Related in: MedlinePlus
Mentions: Figure 2a shows an example of the signal-dropout due to vibration in an axial slice of a diffusion-weighted image (top row) as well as the corresponding shift of the echo in k-space (middle row) and its k-space signal profile along the dashed line (bottom row). The signal-dropout was most apparent when the echo center was shifted towards the shorter k-space edge (red arrow). For the reference DTI data (Fig 2b), which were acquired using a longer slice TR = 170 ms to reduce the vibration effects, the echo center was only marginally shifted and no signal-dropout was visible in the diffusion-weighted image of either blip direction.
Affiliation: Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, University College London, United Kingdom. email@example.com