HIGH SIGNAL REGIONS IN NORMAL WHITE MATTER SHOWN BY HEAVILY T2-WEIGHTED CSF NULLED IR SEQUENCES
HIGH SIGNAL REGIONS IN NORMAL WHITE MATTER SHOWN BY HEAVILY T2-WEIGHTED CSF NULLED IR SEQUENCES
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DOI：
10.1097/00004728-199207000-00002
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发表时间：
1992-07-01
影响因子：
1.3
通讯作者：
BYDDER, GM
中科院分区：
文献类型：
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作者：
HAJNAL, JV;DECOENE, B;BYDDER, GM
反转恢复（IR）序列的反转时间（TI），旨在显着减少或零信号从CSF（TI约2,100毫秒，在1.0 T）和一个非常长的回波时间（TE）为240毫秒被用来成像的两个正常的成年志愿者，一个34岁的男性与内在肿瘤，和一个3个月大的婴儿与梗死的大脑。使用这些非常重的T2加权脉冲序列，成人灰质和白色物质在大脑的许多区域显示出相似的信号强度，但是在半卵圆中心、后内囊、顶桥脑束、枕丘脑放射和脑干区域的正常白色物质显示出比周围灰质或白色物质高得多的信号强度。婴儿显示内囊和枕丘脑放射线中有髓鞘区域的低信号强度，无髓鞘白色物质中的高信号。在许多图像中，与使用脉冲梯度自旋回波序列（TE 130 ms）观察到的白色物质内的高信号分布非常相似，该序列旨在证明各向异性扩散的影响。参数先进，以支持这样的观点，即高信号强度在白色物质束是由于一个或多个长T2的组件，可能与无髓鞘或稀疏髓鞘纤维内的白色事项。与弥散加权图像的相似性可能反映了这两种图像都采用长TE，并且都产生来自CSF的低信号。如果髓磷脂具有与轴浆不同的磁化率，从而当神经纤维的方向不平行于B 0时，在神经纤维周围产生磁场梯度，则水的扩散可能会产生所观察到的对纤维方向的依赖性。白色物质中的高信号区域是图像解释中混淆的潜在来源，并且需要在考虑这些区域变化的情况下测量白色物质中的T2。正常出现的白色物质的概念也需要应用这些差异的知识。在这项研究中使用的IR序列提供了一个非常高的T2依赖性与低信号从CSF和可能是有用的检测疾病的中枢神经系统的成人和儿童。
Inversion recovery (IR) sequences with an inversion time (TI) designed to markedly reduce or null the signal from CSF (TI of approximately 2,100 ms at 1.0 T) and a very long echo time (TE) of 240 ms were used to image the brain of two normal adult volunteers, one 34-year-old man with an intrinsic tumor, and one 3-month-old infant with an infarct. Using these-very heavily T2-weighted pulse sequences, adult gray and white matter showed similar signal intensity in many areas of the brain, but normal white matter in regions of the centrum semiovale, posterior internal capsule, parietopontile tract, occipitothalamic radiation, and brain stem showed a much higher signal intensity than surrounding gray or white matter. The infant displayed a low signal intensity in myelinated regions in the internal capsule and occipitothalamic radiation and a high signal in unmyelinated white matter. In many of the images there were strong similarities to the distribution of high signal within white matter seen with pulsed gradient spin echo sequences (TE 130 ms) designed to demonstrate effects due to anisotropic diffusion. Arguments are advanced to support the view that the high signal intensity in white matter tracts is due to one or more long T2 components that may be associated with unmyelinated or sparsely myelinated fibres within white matter. The resemblance to diffusion weighted images may reflect the fact that both employ long TEs and both produce a low signal from CSF. If myelin possessed a different susceptibility from axoplasm so that magnetic field gradients were generated around nerve fibres when their orientation was not parallel to B0, diffusion of water might then produce the observed dependence on fibre direction. The high signal regions in white matter are a potential source of confusion in image interpretation, and measurements of T2 in white matter need to be made with these regional variations in mind. The concept of normal appearing white matter also needs to be applied with a knowledge of these differences. The IR sequences used in this study provide a very high T2 dependence with a low signal from CSF and may be useful for detecting disease in the CNS of adults and children.