System stability of a 3T-MRI during continuous EPI scan.
The purpose of this study is to evaluate the general stability and image properties of a 3T MRI system newly installed at the ATR-Brain Activity Imaging Center (ATR-BAIC), in addition to a conventional 1.5T system. In this study, we focused on the echo planar imaging (EPI) sequence since continuous EPI with a relatively long duration of up to 30 min is routinely used, and the stabilization of EPI is always a concern. The following five results were obtained: (1) Significant image shifts along the phase direction were observed in the 1.5T data but not in the 3T data, although B0 shifts in both the 1.5T and 3T systems were the same level (1.3 Hz/min); (2) The signal fluctuations were 1/2-1/3 smaller in the 3T system compared with the 1.5T system; (3) The temporal signal-to-noise ratio (TSNR) of the 3T system was 1.7-2.0 (CP-coil) and 2.5-4.0 (12ch-coil) greater than the 1.5T system; (4) We found a low frequency periodic fluctuation (cycles of approximately 30-40 sec), and an increase in noise in the latter half of the long term series, which might originate from the 3T MRI scanner; and (5) Spatial non-uniformity of TSNR and voxels with a linear-trend were observed in the 3T data.
Shimada
Yasuhiro
Y
Brain Activity Imaging Center, ATR-Promotions/Department of Medical Physics and Engineering, Division of Medical Technology and Science, Course of Health Science, Graduate School of Medicine, Osaka University.
Kochiyama
Takanori
T
Fujimoto
Ichiro
I
Masaki
Shinobu
S
Murase
Kenya
K
D016477:Artifacts; D017352:Echo-Planar Imaging / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity