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 x 128 images of cerebral activation during bilateral finger tapping.
Butts
K
K
Magnetic Resonance Laboratory, Mayo Clinic, Rochester, Minnesota 55905.
Riederer
S J
SJ
Ehman
R L
RL
Thompson
R M
RM
Jack
C R
CR
D000005:Abdomen / Q000033:anatomy & histology; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*