Susceptibility Weighted Imaging With Multiple Echoes
Susceptibility Weighted Imaging With Multiple Echoes
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DOI：
10.1002/jmri.21995
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发表时间：
2010-01-01
影响因子：
4.4
通讯作者：
Rauscher, Alexander
中科院分区：
文献类型：
--
作者：
Denk, Christian;Rauscher, Alexander
目的：将敏感性加权成像(SWI)扩展到多个回波，对相位图像进行自适应零差滤波，以提高信噪比(SNR)和对比度噪声比(CNR)，计算静脉成像，并生成高分辨率的R-2*弛豫图。材料和方法：采集5个等距回波的三维多回波梯度回波数据，范围为13~41ms。用调整到回波时间的滤波参数对每个回波的相位图像进行滤波，转换成相位掩模，并与相应的幅度图像组合得到磁化率加权图像。然后对单个图像进行平均。采集常规单次回波数据进行比较。根据震级数据计算了R-2*弛豫速率图。由相位数据得到的场图用于校正R-2*，以消除静磁场背景不均匀的影响。结果：与单次回波图像相比。组合图像的SNR提高了46%，CNR提高了34%到80%。改善了小静脉血管的可见性，并减少了读出方向上的模糊。不同组织类型的R-2*值与文献值有较好的一致性。结论：多回波SWI的采集可以提高SNR和CNR，并可以计算高分辨率的R-2*松弛图。
Purpose: To extend suseeptibility weighted imaging (SWI) to multiple echoes with an adapted homodyne filtering of phase images for the computation of venograms with improved signal to noise ratio (SNR) and contrast to noise ratio (CNR) and to produce high resolution maps of R-2* relaxation.Materials and Methods: Three-dimensional Multi echo gradient echo data were acquired with five equidistant echoes ranging from 13 to 41 ms. The phase images of each echo were filtered with filter parameters adjusted to the echo time, converted into a phase mask, and combined with the corresponding magnitude images to obtain susceptibility weighted images. The individual images were then averaged. Conventional single echo data were acquired for comparison. Maps of R-2* relaxation rates were computed from the magnitude data. Field maps derived from the phase data were used to correct R-2* for the influences from background inhomogeneities of the static magnetic field.Results: Compared with the single echo images. the combined images had an increase in SNR by 46% and an improvement in CNR by 34 to 80%. improved visibility of small venous vessels and reduced blurring along the readout direction. The R-2* values of different tissue types are in good agreement with values from the literature.Conclusion: Acquisition of SWI with multiple echoes leads to an increase in SNR and CNR and it allows the computation of high resolution maps of R-2* relaxation.