Jones Craig K, Whittall Kenneth P, MacKay Alex L
Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada.
Magn Reson Med. 2003 Jul;50(1):206-9. doi: 10.1002/mrm.10492.
The myelin water fraction is calculated, voxel-by-voxel, by fitting decay curves from a multi-echo data acquisition. Curve-fitting algorithms require a high signal-to-noise ratio to separate T(2) components in the T(2) distribution. This work compared the effect of averaging, during acquisition, to data postprocessed with a noise reduction filter. Forty regions, from five volunteers, were analyzed. A consistent decrease in the myelin water fraction variability with no bias in the mean was found for all 40 regions. Images of the myelin water fraction of white matter were more contiguous and had fewer "holes" than images of myelin water fractions from unfiltered echoes. Spatial filtering was effective for decreasing the variability in myelin water fraction calculated from 4-average multi-echo data.
通过对多回波数据采集得到的衰减曲线进行逐体素拟合来计算髓鞘水分数。曲线拟合算法需要高信噪比才能在T(2)分布中分离T(2)成分。这项工作比较了采集过程中平均处理与用降噪滤波器进行数据后处理的效果。对来自五名志愿者的40个区域进行了分析。在所有40个区域中均发现髓鞘水分数变异性持续降低，且均值无偏差。白质髓鞘水分数的图像比未滤波回波的髓鞘水分数图像更连续，“空洞”更少。空间滤波对于降低从4次平均多回波数据计算得到的髓鞘水分数的变异性是有效的。
