Medical University of Vienna, Department of Radiology, Vienna, Austria.
J Magn Reson Imaging. 2010 Aug;32(2):289-97. doi: 10.1002/jmri.22246.
To remove spatial patterns in gradient echo phase images which are caused by susceptibility differences between different tissue types using filtered deconvolution and to evaluate deconvolution effects.
A realistic simulated susceptibility map of the human brain was built and used to evaluate the effects of filtered deconvolution. The simulated susceptibility map was convolved with a filter kernel representing a magnetic dipole resulting in a simulated phase map. The artificial phase map was superimposed with different noise levels and deconvolved using different deconvolution kernels. The resulting contrast-to-noise ratios between white and gray matter of the deconvolved data provide an estimate for an optimal deconvolution kernel for a given noise level. These results were used to deconvolve an in vivo phase model representing the average of 30 phase data sets and also individual phase data acquired at 7 Tesla.
The deconvolved phase model shows a better anatomical agreement with the corresponding magnitude than the original phase model (5% higher kappa coefficient). Visual inspection of the deconvolved individual phase shows a more consistent delineation of blood vessels.
Filtered deconvolution of SWI phase is possible when an appropriate filter kernel is used. This helps to improve region of interest definition as unrealistic phase patterns are removed.
使用滤波反卷积去除梯度回波相位图像中由于不同组织类型之间的磁化率差异引起的空间模式，并评估反卷积效果。
构建了一个真实的人脑模拟磁化率图，并用于评估滤波反卷积的效果。模拟磁化率图与代表磁偶极子的滤波器核卷积，产生模拟相位图。将人工相位图叠加不同的噪声水平，并使用不同的反卷积核进行反卷积。反卷积数据中白质和灰质之间的对比噪声比提供了给定噪声水平下最佳反卷积核的估计。这些结果用于反卷积一个代表 30 个相位数据集平均值的体内相位模型，以及在 7 特斯拉处采集的单个相位数据。
与原始相位模型相比，反卷积后的相位模型与相应的幅度具有更好的解剖一致性（kappa 系数高 5%）。对反卷积后的个体相位进行目视检查显示，血管的描绘更加一致。
当使用适当的滤波器核时，SWI 相位的滤波反卷积是可行的。这有助于通过去除不真实的相位模式来改善感兴趣区域的定义。
