Loyola Marymount University, Los Angeles, CA, USA.
AJR Am J Roentgenol. 2013 Jun;200(6):1234-7. doi: 10.2214/AJR.12.9120.
The objective of our study was to assess MRI issues at 3 T for a newly developed fiducial marker used to localize lung lesions.
A fiducial marker designed for lung lesions (super-Lock Cobra) was investigated at 3 T for magnetic field interactions, MRI-related heating, and artifacts using standardized techniques. Magnetic field interactions were assessed with regard to translational attraction and torque. MRI-related heating was characterized by placing the marker in a gelled-saline-filled head-torso phantom and performing MRI using a transmit-receive radiofrequency body coil at an MR system-reported, whole-body-averaged specific absorption rate of 2.9 W/kg for 15 minutes. Artifacts were measured for the marker on MR images obtained using T1-weighted spin-echo and gradient-echo pulse sequences.
The fiducial marker displayed very low magnetic field interactions (2° deflection angle and no torque) at 3 T. MRI-related heating was at the same level as the "background" (i.e., phantom heating without the marker) temperature rise. Artifacts were relatively small in relation to the size and shape of the marker.
The results of this investigation show that there are no MRI-related safety concerns and, thus, that it would be acceptable (i.e., "MR conditional") for a patient with this new fiducial marker to be examined using MRI at 3 T or less. Artifacts, although relatively small, may create issues if the area of interest is the same as that of the marker or if the interpreting radiologist does not know the marker is present.
我们的研究目的是评估一种新开发的用于定位肺部病变的基准标记物在 3T 下的 MRI 问题。
使用标准化技术，对设计用于肺部病变的基准标记物（超级锁定眼镜蛇）进行磁场相互作用、与 MRI 相关的加热和伪影的研究。磁场相互作用通过平移吸引力和扭矩来评估。通过将标记物置于凝胶化盐填充的头部-躯干体模中，并使用发射-接收射频体线圈在 MR 系统报告的全身平均比吸收率为 2.9 W/kg 的条件下进行 15 分钟的 MRI 来表征与 MRI 相关的加热。使用 T1 加权自旋回波和梯度回波脉冲序列获取的 MR 图像上测量标记物的伪影。
在 3T 下，基准标记物显示出非常低的磁场相互作用（2°偏转角和无扭矩）。与“背景”（即无标记物的体模加热）温度升高相比，与 MRI 相关的加热处于相同水平。与标记物的大小和形状相比，伪影相对较小。
该研究结果表明，没有与 MRI 相关的安全问题，因此，对于带有这种新基准标记物的患者，在 3T 或更低场强下进行 MRI 检查是可以接受的（即“MR 条件下”）。尽管伪影相对较小，但如果感兴趣区域与标记物相同，或者解释放射科医生不知道标记物存在，则可能会产生问题。
