Doppler ultrasound triggering for cardiac MRI at 7T
Doppler ultrasound triggering for cardiac MRI at 7T
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DOI：
10.1002/mrm.27032
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发表时间：
2018-07-01
影响因子：
3.3
通讯作者：
Kraff, O.
中科院分区：
文献类型：
--
作者：
Kording, F.;Ruprecht, C.;Kraff, O.
目的心脏 MR (CMR) 成像的先决条件是图像采集与心动周期充分同步。高场强下的电磁干扰可能会妨碍心电图触发。这项工作的目的是评估多普勒超声触发在7T超高场MRI上进行CMR图像同步的可行性。方法开发了定制的多普勒超声（DUS）触发装置。在研究之前，使用电场和磁场探头以及翻转角图评估了磁共振兼容性。使用 DUS 和脉搏血氧测定法在 13 名健康受试者中以 7T 进行心脏 MR 触发。为了验证触发信号，在 MR 室外比较了心电图、脉搏和 DUS 信号。在短轴和四腔视图中获得屏气电影快速低角度拍摄序列。图像质量由两名高级放射科医生通过心内膜模糊测量进行评估。结果使用和不使用换能器时电场和磁场分布的最大变化为 5%。在 B-1 图和 CMR 成像过程中，未观察到 DUS 和 MRI 之间的干扰。 DUS 触发信号的验证导致与 r=0.99 的心电图信号高度相关。图像和触发质量分析显示没有显着差异。结论多普勒超声作为一种新的触发方法应用于7T CMR。传输线和换能器被当地批准为7T MR条件，并成功通过7T图像同步测试。未来，这种方法需要在更大的患者群体中进行评估。 Magn Reson Med 80:239-247, 2018。(c) 2017 年国际医学磁共振学会。
PurposeA prerequisite for cardiac MR (CMR) imaging is adequate synchronization of image acquisition with the cardiac cycle. Electrocardiogram triggering may be hampered by electromagnetic interferences at high field strength. The purpose of this work is to evaluate the feasibility of Doppler ultrasound triggering for CMR image synchronization at 7T ultra-high-field MRI.MethodsA custom-built Doppler ultrasound (DUS) trigger device was developed. Magnetic resonance compatibility was evaluated using E- and H-field probes and flip angle maps prior to the study. Cardiac MR was performed at 7T in 13 healthy subjects using DUS and pulse oximetry for triggering. For validation of the trigger signal, the electrocardiogram, pulse, and DUS signals were compared outside of the MR room. Breath-hold cine fast low-angle-shot sequences were acquired in short-axis and four-chamber view. Image quality was assessed by two senior radiologists and by measurement of endocardial blurring.ResultsThe maximal change in E- and H-field distributions with and without transducer was 5%. No interferences were observed between DUS and MRI in the B-1 maps and during CMR imaging. Validation of the DUS trigger signal resulted in a high correlation to the electrocardiographic signal of r=0.99. Analysis of image and trigger quality revealed no significant differences.ConclusionDoppler ultrasound was applied as a new trigger method in CMR at 7T. The transmission line and transducer were locally approved as 7T MR conditional, and were successfully tested for image synchronization at 7T. In the future, this method needs to be evaluated in a larger patient population. Magn Reson Med 80:239-247, 2018. (c) 2017 International Society for Magnetic Resonance in Medicine.