Abstract: Objective　To explore the effect of magnetic resonance (MR)-SIM on the image geometric deformation and image quality during the use of external auxiliary equipment. Methods　During the scanning, stepping scanning was used to place the geometric deformation correction body film at the center of the magnet as the 0 position; and the seven spatial positions of 0 mm, ± 60 mm, ± 130 mm, and ± 200 mm were tested. The external auxiliary device was in 4 different states (the common instrument states during the scanning period were as below: the laser light was normally on or off; the high pressure injector operation interface was normally on or off; and the high pressure injector was located in front of or behind the MR-SIM). The impacts of the external laser and high-pressure injector on the images were compared between the groups. Results　The external laser had little effect on image deformation, which basically met the requirements of MR-SIM deformation. The normally open operation interface of the high-pressure injector had big influence on the geometric deformation of the images, and would cause serious RF artifacts at the -130 mm and -200 mm positions, affecting the image quality, and the images deformed obviously; its position did not affect the images obviously. The operation screens of the external laser and the high-pressure injector were normally open. Compared with the case where the operation interface of the injector was normally open, large artifacts appeared in the edge area, and the deformation results of the edge area did not meet the requirements. Conclusions　The state of the high-pressure injector has big influence on the geometric deformation of the images, which is more obvious in the edge area. Under different circumstances, the geometric deformation of the central area of the magnet is small, and there will be no obvious changes. During clinical scanning, the external laser should be kept off, and the operating interface of the high-pressure injector should be off. The sequence of closing the operation interface of the external laser and high-pressure injector should be set in the standard operating procedure for clinical use to reduce its impact on MR images.

Key words: MR-SIM, Image deformation, External laser

摘要： 目的　探讨磁共振（MR）-SIM在外部辅助设备的使用过程中对图像几何形变和图像质量的影响。方法　扫描期间，采用步进式扫描，将几何形变校正体膜放置在以磁体中心为0位，测试0 mm、±60 mm、±130 mm、±200 mm 7个空间位置，分组比较外置激光和高压注射器2个外部辅助设备在4种不同状态下（扫描期间常用仪器状态：激光灯常开或关闭，高压注射器操作界面常开或关闭，高压注射器位于MR-SIM前方或后方）对图像的影响。结果　外置激光对于图像形变影响较小，符合MR-SIM形变的要求。高压注射器操作界面常开对于图像几何形变的影响较大，并会导致-130 mm、-200 mm位置处出现较严重的射频伪影，影响图像质量，图像形变较大，并且其所处位置对图像无明显影响。外置激光与高压注射器操作屏幕常开，相比于注射器操作界面常开的情况，边缘区域会出现较大伪影，且边缘区域形变结果不满足要求。结论　高压注射器的状态对图像几何形变的影响较大，在边缘区域较明显。在不同情况下，磁体中心区域的几何形变都较小，不会有较明显变化。在临床扫描中，应该保持外置激光关闭，且高压注射器的操作界面应处于关闭状态。应在临床使用标准操作流程中，定好关闭外置激光和高压注射器操作界面的顺序，降低其对MR图像的影响。

关键词: 磁共振模拟定位, 图像形变, 外置激光