Department of Biomedical Engineering, University of Wisconsin, Madison, Wisconsin 53792-3252, USA.
J Magn Reson Imaging. 2010 Mar;31(3):725-31. doi: 10.1002/jmri.22066.
To determine the sources of variability of MRE hepatic stiffness measurements using healthy volunteers and patients and to calculate the minimum change required for statistical significance. Hepatic stiffness measured with magnetic resonance elastography (MRE) has demonstrated tremendous potential as a noninvasive surrogate of hepatic fibrosis, although the underlying repeatability of MRE for longitudinal tracking of liver disease has not been documented.
MRE stiffness measurements from 20 healthy volunteers and 10 patients were obtained twice on the same day, and repeated 2-4 weeks later for volunteers in this institutional review board-approved study. A linear mixed effects model was used to estimate the component sources of variability in the data.
The standard deviation of MRE measurements of the same individual on different days is 11.9% (percent of the measured stiffness) using the same reader and 12.0% using different readers. The standard deviation of the difference between two measurements (i.e., longitudinal change in an individual) is 17.4%; the corresponding 95% confidence interval for zero change is (-27.0%, 37.0%).
MRE is a repeatable method for quantifying liver stiffness. Using the described MRE technique, changes greater than 37.0% of the smaller measured stiffness value represent meaningful changes in longitudinal liver stiffness measurements.
通过健康志愿者和患者确定磁共振弹性成像（MRE）肝硬度测量的变异性来源，并计算出具有统计学意义的最小变化量。尽管 MRE 作为肝纤维化的非侵入性替代指标具有巨大潜力，但尚未记录 MRE 对肝脏疾病进行纵向跟踪的重复性的基础。
本机构审查委员会批准的研究中，在同一天对 20 名健康志愿者和 10 名患者进行了两次 MRE 硬度测量，随后在 2 至 4 周后对志愿者进行了重复测量。使用线性混合效应模型来估计数据中变异的组成来源。
使用相同的读者，同一个体在不同日期的 MRE 测量的标准偏差为 11.9%（测量硬度的百分比），而使用不同的读者则为 12.0%。两次测量（即个体的纵向变化）之间差异的标准偏差为 17.4%；零变化的相应 95%置信区间为（-27.0%，37.0%）。
MRE 是一种可重复的定量肝硬度的方法。使用描述的 MRE 技术，测量值较小的 37.0%以上的变化代表纵向肝硬度测量的有意义变化。
