Lupo Janine M, Lee Michael C, Han Eric T, Cha Soonmee, Chang Susan M, Berger Mitchel S, Nelson Sarah J
Department of Radiology, University of California San Francisco, San Francisco, California 94158, USA.
J Magn Reson Imaging. 2006 Sep;24(3):520-9. doi: 10.1002/jmri.20673.
To investigate changes in image and dynamic signal-to-noise ratios (SNRs) of the DeltaR2* curve, as well as magnetic susceptibility-induced artifacts between a standard quadrature head coil and an eight-channel phased-array coil with and without sensitivity-encoding (SENSE) at 3T, compared to the current clinical standard head coil acquisition at 1.5T.
Dynamic susceptibility contrast (DSC) perfusion MRI was performed on 80 brain tumor patients using a gradient-echo, echo-planar imaging (EPI) sequence. Image and dynamic SNR were compared between 1.5T and 3T field strengths, a quadrature and eight-channel phased-array coil, and a conventional vs. partially parallel EPI acquisition with SENSE reconstruction. The amount of geometric distortion and signal dropout was quantified and compared between conventional and SENSE EPI acquisitions within the same exam at 3T.
An initial 2.6-fold elevation in dynamic SNR was observed in normal-appearing white matter when doubling the field strength (P < 0.001), with an additional 1.7-fold increase found when employing an eight-channel phased-array coil (P < 0.002). Compared to the standard 3T eight-channel coil acquisition, the implementation of SENSE reduced the number of voxels experiencing large anterior shifts in the phase-encode direction, lowered the volume of signal dropout by 2.0-11.5%, and allowed a 1.4-fold increase in slice coverage, while only decreasing the dynamic SNR by 22%.
SENSE EPI at 3T yielded a significant improvement in dynamic SNR over the 1.5T acquisitions. A significant reduction in magnetic susceptibility-induced artifacts was achieved with SENSE EPI compared to the standard EPI eight-channel coil acquisition at 3T.
研究在3T场强下，与当前1.5T临床标准头部线圈采集相比，标准正交头部线圈和八通道相控阵线圈在有和没有敏感度编码（SENSE）时，DeltaR2*曲线的图像和动态信噪比（SNR）的变化，以及磁敏感性伪影情况。
使用梯度回波、回波平面成像（EPI）序列对80例脑肿瘤患者进行动态磁敏感对比（DSC）灌注磁共振成像。比较了1.5T和3T场强、正交和八通道相控阵线圈，以及传统与采用SENSE重建的部分并行EPI采集之间的图像和动态SNR。在3T的同一检查中，对传统和SENSE EPI采集中的几何畸变和信号丢失量进行了量化和比较。
当场强加倍时，在外观正常的白质中观察到动态SNR最初升高2.6倍（P < 0.001），当使用八通道相控阵线圈时又额外增加1.7倍（P < 0.002）。与标准3T八通道线圈采集相比，SENSE的实施减少了在相位编码方向上经历大的前部移位的体素数量，使信号丢失体积降低了2.0 - 11.5%，并使切片覆盖范围增加了1.4倍，同时仅使动态SNR降低了22%。
3T下的SENSE EPI在动态SNR方面比1.5T采集有显著改善。与3T的标准EPI八通道线圈采集相比，SENSE EPI显著减少了磁敏感性伪影。
