Correction of read-gradient polarity in EPI and GRASE MRI.

摘要

In an EPI or GRASE magnetic resonance method, phase errors caused by the alternation of the read gradient polarity (Gx) are corrected by obtaining a set of reference measurements with both polarities at low values in the phase encoding (ky) direction. From these reference measurements the phase errors are estimated. Subsequently, the measurements covering the whole of k-space are corrected and a magnetic resonance image obtained in which artefacts due to the alternating polarity of the read gradient are suppressed.