ARTIFACT REDUCTION IN ECHO PLANAR IMAGING W/ PHASE ENCODED REFERENCE SCAN

回声平面成像（EPI）对磁场敏感

Echo-planar imaging (EPI) is sensitive to magnetic field inhomogeneities which lead to signal loss and geometric distortions of the image. The magnetic field inhomogeneities induced due to susceptibility differences, as encountered in the human body, increase with the magnetic field strength. Thus, it is a challenge to implement high resolution EPI techniques on high magnetic field systems. Furthermore, in EPI images, each k-space line has different dephasing in the phase-encoding direction if flow is present, causing artifacts in the phase-encoding direction. In the last grant period, we developed a new phase-encoded referencing scheme for EPI and demonstrated that the new referencing scheme virtually eliminates N/2 ghosts despite the strong field inhomogeneity present at high fields. The image distortion that may arise from Bo inhomogeneity in EPI as well as other ultrafast imaging sequences was also addressed in the last year with a new technique for correction such image degradation.