Interleaved echo planar imaging on a standard MRI system

This work describes an interleaved echo planar imaging (EPI) method for use on a standard whole body scanner. The data acquisition is divided into two to eight repetitions rather than one to two, as implemented by dedicated EPI systems. Interleaving allows the use of a lower sampling bandwidth with a significant increase in signal‐to‐noise. The method also has the advantages of relative ease of implementation, no need for postprocessing to remove image distortion, and no need for shimming on a case‐by‐case basis. The interleaved EPI method was applied to two applications ideally suited to EPI: breathhold T₂‐weighted abdominal imaging and functional imaging. In vivo liver‐lesion contrast as measured in a 35‐patient study showed increased contrast for the Interleaved EPI by an average factor of 1.21 (± 0.34) over conventional spin‐echo imaging. CNR measurements showed the EPI to be comparable with conventional spin echo with a relative factor of 1.00 (± 0.36). Functional imaging with an eight‐shot interleaved EPI sequence provided 128 × 128 images of cerebral activation during bilateral finger tapping.