Department of Radiology, University of California San Diego, San Diego, CA 92103-8226, USA.
J Magn Reson Imaging. 2012 Feb;35(2):318-27. doi: 10.1002/jmri.22816. Epub 2011 Sep 29.
To characterize cardiac motion artifacts in the liver and assess the use of a postprocessing method to mitigate these artifacts in repeat measurements.
Three subjects underwent breathhold diffusion-weighted (DW) scans consisting of 25 repetitions for three b-values (0, 500, 1000 sec/mm(2)). Statistical maps computed from these repetitions were used to assess the distribution and behavior of cardiac motion artifacts in the liver. An objective postprocessing method to reduce the artifacts was compared with radiologist-defined gold standards.
Signal dropout is pronounced in areas proximal to the heart, such as the left lobe, but also present in the right lobe and in distal liver segments. The dropout worsens with b-value and leads to overestimation of the diffusivity. By reference to a radiologist-defined gold standard, a postprocessing correction method is shown to reduce cardiac motion artifact.
Cardiac motion leads to significant artifacts in liver DW imaging; we propose a postprocessing method that may be used to mitigate the artifact and is advantageous to standard signal averaging in acquisitions with multiple repetitions.
描述肝脏中的心脏运动伪影，并评估一种后处理方法在重复测量中减轻这些伪影的效果。
3 名受检者进行屏气式弥散加权（DW）扫描，共包括 25 次重复，b 值分别为（0、500、1000 sec/mm(2)）。使用这些重复序列计算的统计图谱用于评估心脏运动伪影在肝脏中的分布和变化情况。将一种客观的后处理方法用于减少伪影，并与放射科医生定义的金标准进行比较。
在靠近心脏的区域（如左叶），信号缺失较为明显，但在右叶和肝脏的远端节段也存在信号缺失。随着 b 值的增加，信号缺失会加重，导致弥散系数的高估。通过与放射科医生定义的金标准进行比较，后处理校正方法可减少心脏运动伪影。
心脏运动导致肝脏 DW 成像中出现明显的伪影；我们提出了一种后处理方法，可用于减轻伪影，且在多次重复采集时优于标准信号平均法。
