Monitoring cardiac motion in CT using a continuous wave radar embedded in the patient table.
Monitoring cardiac motion in CT using a continuous wave radar embedded in the patient table.
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DOI：
10.1118/1.4886056
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发表时间：
2014-08-01
期刊：
影响因子：
3.8
通讯作者：
KachelrieSS, Marc
中科院分区：
文献类型：
--
作者：
Pfanner, Florian;Allmendinger, Thomas;KachelrieSS, Marc
目的：为了避免运动伪影，医学成像设备通常与患者的心脏运动同步。如今，ECG用于确定心跳并由此触发成像设备。然而，ECG需要额外的努力来准备患者，例如，安装和布线电极，并且它不能确定心脏的运动。评估心脏运动的一个有趣的替代方案是连续波雷达。这项工作的目的是评估这样一个雷达系统，专注于测量心脏motion.METHODS：在860 MHz频段的雷达系统。在雷达系统的预期应用中，天线靠近患者的身体定位，例如，在CT系统的工作台内部。雷达波传播到患者的身体中并且在组织边界处（例如，在肌肉和脂肪组织之间的边界处或在器官的边界处）被反射。在这里，作者专注于心脏运动的检测。雷达系统由硬件和专用信号处理软件组成，用于从雷达信号中提取所需信息。雷达系统的硬件和信号处理算法进行了测试，从10名志愿者的数据。作为参考，ECG与雷达测量同时记录。此外，超声测量和比较的运动信息从雷达data.Results：根据作者的志愿者（测试人员）的测量，心跳和心率可以很好地使用所提出的雷达系统检测。作者还能够从雷达数据中提取心脏运动本身的幅度和相位。超声测量证实了这一点。然而，这种运动的评估是依赖于天线的位置，它仍然不清楚天线看到的运动是最相关的CT imaging.CONCLUSIONS：连续波雷达在天线的近场操作可以用来确定心跳和心脏运动的人没有特殊的病人准备。作者的雷达系统非常靠近患者，因为它嵌入在患者检查床中，但它与患者或患者皮肤没有直接接触（因为需要采集患者的ECG）。因此，雷达运动监测不需要特殊的患者准备。与今天使用的其他方法相比，这是一个重大的改进。作者的雷达系统可以允许根据心脏相位触发CT扫描，而不需要ECG，并且它允许在扫描开始之前确定安静的并且因此有利的心脏相位。
PURPOSE: To avoid motion artifacts, medical imaging devices are often synchronized with the patient's cardiac motion. Today, the ECG is used to determine the heartbeat and therewith trigger the imaging device. However, the ECG requires additional effort to prepare the patient, e.g., mount and wire electrodes and it is not able to determine the motion of the heart. An interesting alternative to assess the cardiac motion is continuous wave radar. The aim of this work is to evaluate such a radar system focusing on measuring the cardiac motion.METHODS: A radar system operating in the 860 MHz band is used. In the intended application of the radar system, the antennas are located close to the patient's body, for example, inside the table of a CT system. The radar waves propagate into the patient's body and are reflected at tissue boundaries, for example, at the borderline between muscle and adipose tissue, or at the boundaries of organs. Here, the authors focus on the detection of cardiac motion. The radar system consists of hardware as well as of dedicated signal processing software to extract the desired information from the radar signals. The radar system hardware and the signal processing algorithms were tested with data from ten volunteers. As a reference, the ECG was recorded simultaneously with the radar measurements. Additionally, ultrasound measurements are performed and compared with the motion information from the radar data.RESULTS: According to the authors' measurements on volunteers (test persons), the heartbeat and heart rate can be detected well using the proposed radar system. The authors were further able to extract the amplitude and phase of the heart motion itself from the radar data. This was confirmed by the ultrasound measurements. However, this motion assessment is dependent on the antenna position and it remains unclear which antenna sees the motion that is the most relevant to CT imaging.CONCLUSIONS: A continuous wave radar operating in the near field of the antennas can be used to determine the heartbeat and the cardiac motion of humans without special patient preparation. The authors' radar system is very close to the patient because it is embedded in the patient table, but it has no direct contact to the patient or to the patient skin (as it would be necessary to acquire the ECG of the patient). Therefore, radar motion monitoring does not require special patient preparation. In contrast to other methods used today, this is a significant improvement. The authors' radar system may allow to trigger a CT scan in dependency of the cardiac phase, without requiring an ECG, and it allows to determine quiet, and thus favorable, heart phases prior to the scan start.