Thunberg Per, Karlsson Matts, Wigström Lars
Department of Biomedical Engineering, Orebro University Hospital, Orebro, Sweden.
Magn Reson Med. 2003 Nov;50(5):1061-8. doi: 10.1002/mrm.10634.
The purpose of this study was to evaluate the accuracy and reproducibility of phase contrast imaging using the sensitivity encoding (SENSE) method at different reduction factors. Analytical expressions were derived that state how reproducibility is influenced for velocity and flow measurements. Computer simulations, and in vitro and in vivo studies were performed in order to validate these expressions and to assess how accuracy is affected when different reduction factors are applied. It was shown that reproducibility depends on the reduction and geometry factors. Since the geometry factor varies spatially, so does the reproducibility for phase contrast imaging. In areas with high geometry factors, the standard deviation (SD) may become so large that aliasing occurs. The accuracy of phase contrast imaging is not influenced directly when SENSE is used, but may be indirectly influenced due to high SDs of the measured phase that may subsequently cause aliasing. The current results show that it is possible to achieve accurate flow measurements even at high reduction factors. By taking the geometry factor into account, it may be possible to find areas where phase contrast imaging is accurate even at high reduction factors.
本研究的目的是评估使用灵敏度编码（SENSE）方法在不同缩减因子下相位对比成像的准确性和可重复性。推导了关于速度和流量测量中可重复性如何受到影响的解析表达式。进行了计算机模拟以及体外和体内研究，以验证这些表达式，并评估应用不同缩减因子时准确性如何受到影响。结果表明，可重复性取决于缩减因子和几何因子。由于几何因子在空间上变化，相位对比成像的可重复性也会如此。在几何因子较高的区域，标准差（SD）可能会变得很大以至于出现混叠。使用SENSE时，相位对比成像的准确性不会直接受到影响，但可能会由于测量相位的高标准差而间接受到影响，这随后可能导致混叠。当前结果表明，即使在高缩减因子下也有可能实现准确的流量测量。通过考虑几何因子，有可能找到即使在高缩减因子下相位对比成像也准确的区域。
