Martinez Jessica A, Serano Peter, Ennis Daniel B
Form the Departments of Radiological Sciences and Bioengineering, University of California, Los Angeles, Calif (J.A.M.); ANSYS, Canonsburg, Pa (P.S.); and Department of Radiological Sciences, Stanford University, 1201 Welch Rd, Stanford, CA 94305 (J.A.M., D.B.E.).
Radiol Cardiothorac Imaging. 2019 Aug 29;1(3):e190006. doi: 10.1148/ryct.2019190006.
To evaluate changes in patient orientation to mitigate radiofrequency-induced lead-tip heating (LTH) during MRI.
LTH was evaluated for device type, lead path, and distance to the isocenter of a 1.5-T MRI system. LTH for 378 conditions in both head-first (HF) and feet-first (FF) orientations was measured for nine MRI-unsafe cardiac active implantable medical devices (AIMDs) placed along three (two anatomic, one planar) left-sided lead paths at nine landmark locations. The devices were exposed to 5 minutes of continuous radiofrequency energy at 4 W/kg whole-body specific absorption rate.
LTH was greater in HF than in FF orientation for the planar and one anatomic lead path ( < .05). LTH was significantly affected by lead path, distance to isocenter, and patient orientation (all < .05), but not by cardiac AIMD device type. Maximum LTH was observed in an HF orientation for the planar lead path when the lead tip was at isocenter (right ventricular [RV] lead: 32.0 °C ± 16.3 [standard deviation], right atrial [RA] lead: 16.1°C ± 9.3). In the FF orientation, LTH was significantly reduced (RV lead: 1.6°C ± 1.4; mean RA lead: 0.5°C ± 1.0; = .008).
LTH for supine FF patient orientations among patients with anterior left-sided cardiac AIMDs can be significantly lower than LTH for supine HF orientations. There was no scenario in which LTH was significantly worse in the FF position. Changing patient orientation is a simple method to reduce radiofrequency-induced LTH.© RSNA, 2019See also the commentary by Litt in this issue.
评估患者体位变化对减轻磁共振成像（MRI）期间射频诱导的导线尖端发热（LTH）的作用。
针对设备类型、导线路径以及与1.5T MRI系统等中心的距离评估LTH。在九个地标位置，沿着三条（两条解剖路径、一条平面路径）左侧导线路径放置九个MRI不安全的心脏有源植入式医疗器械（AIMD），测量头先入（HF）和脚先入（FF）两种体位下378种情况的LTH。这些设备在全身比吸收率为4W/kg的条件下暴露于5分钟连续射频能量中。
对于平面和一条解剖导线路径，HF体位的LTH高于FF体位（P<0.05）。LTH受导线路径、与等中心的距离和患者体位显著影响（均P<0.05），但不受心脏AIMD设备类型影响。当导线尖端位于等中心时，平面导线路径在HF体位观察到最大LTH（右心室[RV]导线：32.0℃±16.3[标准差]，右心房[RA]导线：16.1℃±9.3）。在FF体位，LTH显著降低（RV导线：1.6℃±1.4；RA导线平均：0.5℃±1.0；P = 0.008）。
左前侧心脏AIMD患者中，仰卧FF体位的LTH可显著低于仰卧HF体位的LTH。在FF体位下，没有LTH显著更差的情况。改变患者体位是减少射频诱导LTH的一种简单方法。©RSNA，2019另见本期Litt的评论。
