Greif W L, Buxton R B, Lauffer R B, Saini S, Stark D D, Wedeen V J, Rosen B R, Brady T J
Radiology. 1985 Nov;157(2):461-6. doi: 10.1148/radiology.157.2.4048456.
Paramagnetic agents enhance contrast between tissues in magnetic resonance (MR) imaging by altering tissue relaxation times. The effect of these changes on MR image intensity depends in part on the choice of operator-controlled pulse sequence parameters. With the newly described paramagnetic hepatobiliary contrast agent, iron(III) ethylenebis-(2-hydroxyphenylglycine), Fe(EHPG)-, an in vivo experimental analysis of pulse sequence optimization was performed on the rat. We compared the enhancement of the liver divided by background noise, EL/N, of standard inversion-recovery (IR) and spin-echo (SE) T1-weighted pulse sequences and several pulse sequences theoretically predicted to have improved EL/N. Optimization of the echo time (TE = TEmin) gave a substantial (greater than 60%) increase in EL/N over the standard IR and SE pulse sequences. Images obtained with optimized repetition rate and inversion time gave only a slight additional improvement. Within the uncertainties of our relaxation measurements, the measured changes in EL/N with pulse sequence optimization corresponded well with theoretical predictions. With the experimental and theoretical data, the importance of using a short echo time to obtain maximal T1 contrast in contrast-enhanced MR imaging and the relative merits of optimized SE versus IR pulse sequences for contrast-enhanced MR imaging are discussed.
顺磁性剂通过改变组织弛豫时间来增强磁共振（MR）成像中组织之间的对比度。这些变化对MR图像强度的影响部分取决于操作员控制的脉冲序列参数的选择。使用新描述的顺磁性肝胆造影剂三价铁乙二胺双（2-羟基苯甘氨酸）（Fe（EHPG）），对大鼠进行了脉冲序列优化的体内实验分析。我们比较了标准反转恢复（IR）和自旋回波（SE）T1加权脉冲序列以及理论上预测具有改善的EL/N的几个脉冲序列的肝脏增强除以背景噪声（EL/N）。回波时间的优化（TE = TEmin）使EL/N比标准IR和SE脉冲序列大幅增加（超过60%）。用优化的重复率和反转时间获得的图像仅略有额外改善。在我们弛豫测量的不确定性范围内，脉冲序列优化后EL/N的测量变化与理论预测非常吻合。结合实验和理论数据，讨论了在对比增强MR成像中使用短回波时间以获得最大T1对比度的重要性以及优化的SE与IR脉冲序列在对比增强MR成像中的相对优点。
