磁共振门静脉成像技术探讨

The technique of magnetic resonance portography

目的：通过改变翻转角试图优选出一种最佳翻转角的快速准确的磁共振门静脉血流成像方法，并尽可能消除呼吸运动的影响。材料与方法：采用Ｓｉｇｎａ１．５Ｔ磁共振仪随机对５８例上腹部ＭＲ检查者进行门脉血流成像，其中快速梯度回波间断闭气扫描１８例，采用２０°、３０°和４５°三种不同翻转角。梯度回波加呼吸门控法共扫描４０例，均采用３０°翻转角。所有图像均经三维处理，并采用双盲法评价门脉显示效果。结果：间断闭气ＭＲ门脉成像选择３０°翻转角，图像信噪比、对比度及血管亮度比２０°或４５°为优，此技术受呼吸影响较大，而呼吸门控技术的运用可大大消除呼吸运动的影响。结论：选择３０°翻转角并加用呼吸门控的门脉血流成像技术是较为有效的门脉成像方法之一，它能较好地显示门脉主干及分支。

Purpose: To select a fast accurate method of magnetic resonance portography (MRP) with the optimal flip angle, and to minimize respiratory motion artifact. Materials and methods: Images were obtained on a 1.5T Signa system. Fifty eight nonconsecutive patients underwent MRP after normal MR imaging. Eighteen patients were examined with fast gradient recalled echo (FGRE) and breath holding sequence using different flip angles of 20°, 30°, 45°. Forty patients were studied with gradient recalled echo (GRE) and respiratory compensation (RC) sequence using only 30° flip angle. All images were subsequently post processed using three dimentional maximum intensity projection (3D MIP), the MRP images were assessed using double blind method. Results: FGRE with breath hold and 30° flip angle is better than 20° or 45° in terms of image contrast enhancement of vessels and signal to noise ratio, but this technique was affected by respiratory motion artifact which was reduced by using GRE with RC. Conclusion: GRE with RC and 30° flip angle is an efficent method for MRP being able to demonstrate the main portal vein and its branches, and helpful to diagnosis and surgery.