de Lange E E, Mugler J P, Bertolina J A, Gay S B, Janus C L, Brookeman J R
Department of Radiology, University of Virginia Health Sciences Center, Charlottesville 22908.
Magn Reson Imaging. 1991;9(4):469-76. doi: 10.1016/0730-725x(91)90031-g.
We have implemented an MR technique that employs a rapid gradient echo sequence, preceded by magnetization preparation pulses to provide T1- and T2-weighted tissue contrast. With this technique, which can be identified as a member of a new family of pulse sequences, generically named Magnetization Prepared RApid Gradient Echo (MP-RAGE), very short repetition times are used, allowing acquisition times of less than one second and images virtually free of motion-induced artifacts during quiet respiration. Fifteen patients with known liver lesions (metastases, hemangiomas, and cysts) were examined using T1- and T2-weighted 2-dimensional MP-RAGE sequences, and the images were compared with conventional T1- and multi-echo T2-weighted spin-echo (SE) sequences. Signal difference-to-noise ratios (SD/Ns) of the lesions were calculated for all pulse sequences using corresponding axial images and were normalized for voxel volume. The mean normalized SD/Ns of the MP-RAGE sequences were generally comparable to those for the SE sequences. In addition, there were no noticeable respiratory artifacts on the MP-RAGE images whereas these were clearly present on the T2-weighted SE images and to a lesser degree on the T1-weighted SE images. It is concluded that the MP-RAGE technique could become an important method for evaluating the liver for focal disease.
我们实施了一种磁共振（MR）技术，该技术采用快速梯度回波序列，并在其之前施加磁化准备脉冲，以提供T1加权和T2加权的组织对比度。通过这种技术（可被视为一个新的脉冲序列家族的成员，一般称为磁化准备快速梯度回波序列（MP-RAGE）），使用了非常短的重复时间，使得采集时间少于一秒，并且在安静呼吸期间图像几乎没有运动伪影。使用T1加权和T2加权的二维MP-RAGE序列对15名已知肝脏病变（转移瘤、血管瘤和囊肿）的患者进行了检查，并将图像与传统的T1加权和多回波T2加权自旋回波（SE）序列进行了比较。使用相应的轴向图像计算所有脉冲序列中病变的信号差异与噪声比（SD/N），并对体素体积进行归一化。MP-RAGE序列的平均归一化SD/N通常与SE序列的相当。此外，MP-RAGE图像上没有明显的呼吸伪影，而在T2加权SE图像上明显存在这些伪影，在T1加权SE图像上程度较轻。结论是，MP-RAGE技术可能成为评估肝脏局灶性疾病的一种重要方法。
