A method of generalized projections (MGP) ghost correction algorithm for interleaved EPI.

K J Lee; N G Papadakis; D C Barber; I D Wilkinson; P D Griffiths; M N J Paley

doi:10.1109/tmi.2004.827970

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A method of generalized projections (MGP) ghost correction algorithm for interleaved EPI.

K J Lee·N G Papadakis·D C Barber·I D Wilkinson·P D Griffiths·M N J Paley

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Abstract

Investigations into the method of generalized projections (MGP) as a ghost correction method for interleaved EPI are described. The technique is image-based and does not require additional reference scans. The algorithm was found to be more effective if a priori knowledge was incorporated to reduce the degrees of freedom, by modeling the ghosting as arising from a small number of phase offsets. In simulations with phase variation between consecutive shots for n-interleaved echo planar imaging (EPI), ghost reduction was achieved for n = 2 only. With no phase variation between shots, ghost reduction was obtained with n up to 16. Incorporating a relaxation parameter was found to improve convergence. Dependence of convergence on the region of support was also investigated. A fully automatic version of the method was developed, using results from the simulations. When tested on in vivo 2-, 16-, and 32-interleaved spin-echo EPI data, the method achieved deghosting and image restoration close to that obtained by both reference scan and odd/even filter correction, although some residual artifacts remained.

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K J Lee, N G Papadakis, D C Barber, I D Wilkinson, P D Griffiths, M N J Paley. 2004. A method of generalized projections (MGP) ghost correction algorithm for interleaved EPI.. https://doi.org/10.1109/tmi.2004.827970

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