Sommer T, Vahlhaus C, Lauck G, von Smekal A, Reinke M, Hofer U, Block W, Träber F, Schneider C, Gieseke J, Jung W, Schild H
Dept. of Radiology, University of Bonn, Sigmund-Freud-Str 25, 53127 Bonn, Germany.
Radiology. 2000 Jun;215(3):869-79. doi: 10.1148/radiology.215.3.r00jn08869.
To evaluate the safety and feasibility of magnetic resonance (MR) imaging at 0.5 T in patients with implanted cardiac pacemakers.
Twenty-one models of pacemakers and 44 pacemaker electrodes were exposed to in vitro MR imaging with continuous registration of pacemaker output and temperature at the lead tip. Prior to MR imaging examination, pacemakers were programmed to an asynchronous mode (A00, V00, or D00). Pacemakers were examined before and after MR imaging. Forty-four patients with implanted pacemakers underwent 51 MR imaging examinations under cardiologic surveillance, continuous electrocardiography, pulse oximetry, and capnographic monitoring.
MR imaging was safely performed in all patients. None of the pacemakers displayed a pacing dysfunction at MR imaging. No changes occurred in the programmed parameters in any device tested in vivo or in vitro. Maximum increases in the temperature at the lead tips were 8.90 degrees C at a specific absorption rate (SAR) of 0.6 W/kg and 23.50 degrees C under a worst-case radio-frequency (RF) heating condition with an SAR of 1.3 W/kg.
MR imaging at 0.5 T can be safely performed in patients with implanted pacemakers in carefully selected clinical circumstances when appropriate strategies (programming to an asynchronous mode, adequate monitoring techniques, limited RF exposure) are used.
评估0.5T磁共振成像（MR）在植入心脏起搏器患者中的安全性和可行性。
将21种型号的起搏器和44根起搏器电极置于体外进行MR成像，同时持续记录起搏器输出及导线尖端温度。在MR成像检查前，将起搏器程控为异步模式（A00、V00或D00）。在MR成像前后对起搏器进行检查。44例植入起搏器的患者在心脏监测、连续心电图、脉搏血氧饱和度监测和二氧化碳图监测下接受了51次MR成像检查。
所有患者均安全完成MR成像。在MR成像过程中，无一例起搏器出现起搏功能障碍。在体内或体外测试的任何设备中，程控参数均未发生变化。在比吸收率（SAR）为0.6W/kg时，导线尖端温度最高升高8.90℃；在SAR为1.3W/kg的最坏情况下的射频（RF）加热条件下，温度最高升高23.50℃。
在精心选择的临床情况下，当采用适当策略（程控为异步模式、足够的监测技术、有限的RF暴露）时，植入起搏器的患者可以安全地进行0.5T的MR成像。
