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Centric reordered echo planar imaging (EPI) for phase contrast MRI
© Chung et al; licensee BioMed Central Ltd. 2010
Published: 21 January 2010
Limited temporal resolution underestimates peak velocities assessed by phase contrast MRI (PC-MRI) . Segmented EPI with partial Fourier as previously proposed  has relatively long TE, and is prone to chemical-shift artifact. We propose centric reordered water-excitation EPI for PC-MRI with short TE and fat suppression. It improves temporal resolution by twofold while halving scan time compared with turboFLASH.
Design a centric reordered EPI sequence for PC-MRI, and compare it with turboFLASH in healthy volunteers.
Imaging parameters used in the study.
Bandwidth per pixel
TSENSE rate 2
9 echoes/RF pulse
134 × 192
iPAT rate 2, 24 extra lines
125 × 192
For each (n = 8) healthy volunteers in this IRB approved study, an imaging plane perpendicular to the ascending aorta was prescribed. Aortic flow was imaged twice using each of the two sequences. Argus (Siemens Healthcare, Germany) was used to find the peak velocity (PV) and flow volume (FV). PVs from EPI were obtained using 5-pixel spatial averaging to account for bandwidth related SNR differences between EPI and turboFLASH. PV and FV from each volunteer were averaged for one sided and two sided t-tests respectively
Centric reordered EPI provided short TE and reduced sensitivity to turbulence and minimized T2* effects. Fat suppression improved image quality. The volunteer study results suggested that the high temporal resolution of EPI improves peak velocity sampling, and the shortened scan time makes the technique clinically attractive.
This article is published under license to BioMed Central Ltd.