Tronnier V M, Staubert A, Hähnel S, Sarem-Aslani A
Department of Neurosurgery, University Hospital, Heidelberg College of Medicine, Germany.
Neurosurgery. 1999 Jan;44(1):118-25; discussion 125-6. doi: 10.1097/00006123-199901000-00073.
The goal was to assess the safety of magnetic resonance imaging (MRI) with implanted neurostimulators, in an in vitro and in vivo study.
Two different implantable pulse generators (IPGs) (ITREL II and 3; Medtronic, Minneapolis, MN) and different leads (separately and connected to an IPG) were tested in three different MRI scanners (0.2, 0.25, and 1.5 T). Measurements of the induced voltages (using an external oscilloscope) and the induced heat (using an infrared camera) were performed in an in vitro study. Finally, 38 patients with implanted neurostimulator systems (leads and IPGs) underwent MRI in 50 examinations, with continuous monitoring by a physician with uninterrupted visual and vocal contact with the patient. Twenty-five patients were studied prospectively, with documented printouts of the parameter settings before and after MRI.
An induced voltage of 2.4 to 5.5 V was measured in the experimental configuration with a lead connected to an IPG. The voltage was higher with the leads alone, compared with the leads connected to the IPG, and was dependent on the MRI scanner, the sequences, and the type of lead. No heat induction was observed in any part of the hardware. No change of pulse shape or change of IPG parameters was observed during MRI. No adverse effects occurred in patients with chronically implanted deep brain leads connected to an IPG.
MRI can be safely performed in patients with implanted neurostimulation systems with the tested deep brain leads connected to an IPG (ITREL II and 3), with running parameters. No heat induction was detected, and the experimentally measured induced voltage did not seem to harm the patients. Only the reed switch of the IPGs was activated; the other parameters remained unchanged. Further investigations must be performed to study the local electrical effects in larger plate electrodes; these effects might cause slight discomfort. There is no danger with any type of electrode during MRI examinations if the electrodes lie outside the region of interest. These observations are restricted to the tested devices. A conscientious estimation of the risks and benefits of MRI for patients with implanted devices is recommended. If the type of device is not known to the examiner, MRI should still be considered to be contraindicated.
在一项体外和体内研究中评估植入神经刺激器时进行磁共振成像（MRI）的安全性。
在三种不同的MRI扫描仪（0.2 T、0.25 T和1.5 T）中测试了两种不同的植入式脉冲发生器（IPG）（ITREL II和3型；美敦力公司，明尼阿波利斯，明尼苏达州）以及不同的导线（单独的和连接到IPG的）。在体外研究中进行了感应电压测量（使用外部示波器）和感应热测量（使用红外热像仪）。最后，38例植入神经刺激器系统（导线和IPG）的患者接受了50次MRI检查，由一名医生持续监测，医生与患者保持不间断的视觉和语音联系。对25例患者进行了前瞻性研究，记录了MRI前后参数设置的打印输出。
在导线连接到IPG的实验配置中测得感应电压为2.4至5.5 V。与连接到IPG的导线相比，单独导线时的电压更高，并且取决于MRI扫描仪、序列和导线类型。在硬件的任何部位均未观察到热感应。MRI期间未观察到脉冲形状变化或IPG参数变化。连接到IPG的慢性植入深部脑导线的患者未出现不良反应。
对于植入了连接到IPG（ITREL II和3型）的经测试深部脑导线且运行参数正常的神经刺激系统的患者，可以安全地进行MRI检查。未检测到热感应，实验测得的感应电压似乎不会对患者造成伤害。仅IPG的簧片开关被激活；其他参数保持不变。必须进行进一步研究以探讨较大平板电极中的局部电效应；这些效应可能会引起轻微不适。如果电极位于感兴趣区域之外，则在MRI检查期间任何类型的电极都没有危险。这些观察结果仅限于测试的设备。建议对植入设备患者进行MRI检查的风险和益处进行认真评估。如果检查者不知道设备类型，仍应认为MRI检查是禁忌的。
