Sir Harry Smith Community College, Whittlesey, PE7 1XB, UK.
Physiol Meas. 2013 Jun;34(6):659-69. doi: 10.1088/0967-3334/34/6/659. Epub 2013 May 29.
There has been a surge of interest in using electrical impedance tomography (EIT) for monitoring regional lung ventilation, however, EIT is an ill-conditioned problem, and errors/noise in the boundary voltages can have an undesirable effect on the quality of the final image. Most EIT systems in clinical usage use serial data collection hence data used to create a single image will have been collected at different times. This paper presents a study of the resulting image distortion, and proposes a method for correcting this lag in situations where the frame rate is insufficient to prevent significant image degradation. Significant correlation between the standard deviation of the time dependent reciprocity error and time delay dLe between the reciprocal electrode combinations was found for both adult and neonate data. This was reduced when the data was corrected for dLe. Original and corrected data was reconstructed with the GREIT algorithm and visible differences were found for the neonate data. Ideally EIT systems should be run at a frame rate of at least 50 times the frequency of the dominant and interesting physiological signals. Where this is not practical, the intra-frame system timings should be determined and lag corrected for.
人们对使用电阻抗断层成像（EIT）监测区域性肺通气的兴趣日益浓厚，但 EIT 是一个病态问题，边界电压中的误差/噪声会对最终图像的质量产生不良影响。大多数在临床中使用的 EIT 系统采用串行数据采集，因此用于创建单个图像的数据是在不同时间采集的。本文研究了由此产生的图像失真，并提出了一种在帧率不足以防止图像严重退化的情况下纠正这种滞后的方法。对于成人和新生儿数据，都发现时间相关互易误差的标准偏差与互易电极组合之间的时间延迟 dLe 之间存在显著相关性。当对 dLe 进行校正时，这种相关性降低了。原始数据和校正数据都使用 GREIT 算法进行了重建，对于新生儿数据，可以发现明显的差异。理想情况下，EIT 系统的帧率应至少是主要和感兴趣的生理信号频率的 50 倍。在不切实际的情况下，应确定帧内系统定时并进行滞后校正。
