Centric reordered echo planar imaging (EPI) for phase contrast MRI
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BioMed Central
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Poster presentation
Centric reordered echo planar imaging (EPI) for phase contrast MRI Yiu-Cho Chung*1, Yu Ding2 and Orlando Simonetti2 Address: 1Siemens Healthcare, Columbus, OH, USA and 2The Ohio State University, Columbus, OH, USA * Corresponding author
from 13th Annual SCMR Scientific Sessions Phoenix, AZ, USA. 21-24 January 2010 Published: 21 January 2010 Journal of Cardiovascular Magnetic Resonance 2010, 12(Suppl 1):P94
doi:10.1186/1532-429X-12-S1-P94
Abstracts of the 13th Annual SCMR Scientific Sessions - 2010
Meeting abstracts - A single PDF containing all abstracts in this Supplement is available here. http://www.biomedcentral.com/content/files/pdf/1532-429X-11-S1-infoThis abstract is available from: http://jcmr-online.com/content/12/S1/P94 © 2010 Chung et al; licensee BioMed Central Ltd.
Introduction Limited temporal resolution underestimates peak velocities assessed by phase contrast MRI (PC-MRI) [1]. Segmented EPI with partial Fourier as previously proposed [2] 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.
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 5pixel spatial averaging to account for bandwidth related SNR differences between EPI and turboFLASH. PV and FV
Purpose Design a centric reordered EPI sequence for PC-MRI, and compare it with turboFLASH in healthy volunteers.
Methods Sequences The prospective triggered EPI sequence used centric reordering [3], fast, flow-compensated water excitation [4] and TSENSE [5]. Concomitant gradient effects were corrected [6]. The sequence was implemented on a 1.5 T scanner (MAGNETOM Avanto, Siemens Healthcare, Germany) and its performance was compared to turboFLASH (imaging parameters in Table 1). The TR/TE/flip angle were 12.4 ms/2.4 ms (effective)/15o-25o for EPI, and 5 ms/ 1.9 ms/25o for turboFLASH. EPI echo spacing = 690 μs. In both cases, venc = 150-200 cm/s, pixel ~2.3 × 2 mm2, slice = 6-8 mm. Imaging/Analysis 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
Figure (b) Magnitude echoes 1 images from turboflash, 5 segments (a) and EPI, 9 Magnitude images from turboflash, 5 segments (a) and EPI, 9 echoes (b). The circle marked the aortic flow. (c) and (d) show the corresponding phase images.
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Journal of Cardiovascular Magnetic Resonance 2010, 12(Suppl 1):P94
http://jcmr-online.com/content/12/S1/P94
Table 1: Imaging parameters used in the study.
PAT
Bandwidth per pixel
k-space traversal
Image Matrix
Temporal resolution
Scan time
EPI
TSENSE rate 2
2005 Hz
9 echoes/RF pulse
134 × 192
25 ms
8 beats
Turboflash
iPAT r
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