Correction of eddy current-induced artefacts in diffusion tensor imaging using iterative cross-correlation
Correction of eddy current-induced artefacts in diffusion tensor imaging using iterative cross-correlation
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DOI：
10.1016/s0730-725x(99)00026-0
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发表时间：
1999-09-01
影响因子：
2.5
通讯作者：
Bastin, ME
中科院分区：
文献类型：
--
作者：
Bastin, ME
在扩散张量成像实验中存在的强涡流产生的回波平面图像的几何失真是扩散系数的准确量化和基于它们的扩散各向异性的测量的主要混淆。在此，rye研究了如何将最初由Haselgrove和摩尔（Magn. Reson，Med.36：960-964; 1996）提出的基线和扩散加权图像（DWI）的迭代互相关（ICC）方法扩展到校正高b值DWI，而不需要从低b值图像确定的失真参数的外推。合成脑图像的Monte Carlo模拟显示，b矩阵的迹线Tr（B）的最大值约为300 s mm（-2），在该最大值处，通过与未失真的基线图像直接比较，可以准确地校正失真的DWI。脑脊液信号的去除极大地扩展了Tr（B）的该值（高达约2000 s mm（-2）），从而允许基线和失真图像的直接比较。使用ICC失真参数确定从单独的校准水幻影图像也进行了调查，并发现是有效的，在纠正观察到的几何失真的DWI收集作为人类志愿者扩散张量成像研究的一部分。这项工作表明，在高B值下采集的失真DWI可以使用ICC算法进行校正，而无需收集额外的低b值图像，从而允许在定量患者检查中实施基于收集少量DWI的测量表观扩散张量D的简化方法。(C)1999 Elsevier Science Inc.
Geometric distortions of echo-planar images produced by the strong eddy currents present in the diffusion tensor imaging experiment are a major confound to the accurate quantification of diffusion coefficients, and measures of diffusion anisotropy based upon them. Here rye investigate how the method of iterative cross-correlation (ICC) of baseline and diffusion-weighted images (DWIs) originally proposed by Haselgrove and Moore (Magn. Reson, Med. 36:960-964; 1996) can be extended to correct high b-value DWIs, without the need for extrapolation of distortion parameters determined from low b-value images. Monte Carlo simulations of synthetic brain images show that the maximum value of the trace of the b-matrix, Tr(b), at which distorted DWIs can be accurately corrected by direct comparison with the undistorted baseline image is approximately 300 s mm(-2). Removal of the cerebrospinal fluid signal greatly extends this value of Tr(b) (up to approximately 2000 s mm(-2)), thereby allowing direct comparison of baseline and distorted images. The use of ICC distortion parameters determined from separate calibrations of water phantom images is also investigated, and found to be effective in correcting geometric distortions observed in the DWIs collected as part of a human volunteer diffusion tensor imaging study. This work suggests that distorted DWIs acquired at high values of b may be corrected using the ICC algorithm without collecting additional low b-value images, thus allowing simplified methods of measuring the apparent diffusion tensor D, based on collecting a small number of DWIs, to be implemented in quantitative patient examinations. (C) 1999 Elsevier Science Inc.