THE LOSS OF SMALL OBJECTS IN VARIABLE TE IMAGING - IMPLICATIONS FOR FSE, RARE, AND EPI
THE LOSS OF SMALL OBJECTS IN VARIABLE TE IMAGING - IMPLICATIONS FOR FSE, RARE, AND EPI
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DOI：
10.1002/mrm.1910280103
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发表时间：
1992-11-01
影响因子：
3.3
通讯作者：
GORE, JC
中科院分区：
文献类型：
--
作者：
CONSTABLE, RT;GORE, JC
最近有报道称，不同相位编码视图的采集顺序对MR图像质量的重要性具有可变TR和TE序列。已经表明，有效点扩展函数（PSF）可以通过改变TE或TR或两者来操纵，每个相位编码步骤。本文探讨了在一个可变的TE序列和成像和组织参数的依赖性的PSF的行为。它示出的PSF是不同的每种组织类型，其对组织对比度的影响是结构的形状和大小的函数。从小物体的信号损失，当有效的PSF是广泛的，并在实际的MR图像中检测到这种现象的困难的重要问题进行说明。它表明，PSF可以产生显着的模糊和损失的对象的对比度在快速自旋回波图像，但这种模糊在实践中可能并不明显，因为噪声不受PSF。它也表明，信号从小病灶短T2可以很容易地通过这种模糊机制丢失。强调了小物体信号损失的重要性及其对快速自旋回波或快速采集弛豫增强和回波平面成像等序列临床使用的影响。© 1992 Academic Press，Inc.
The importance to MR image quality of the order of acquisition of different phaseencoded views with sequences that have variable TR and TE has been recently reported. It has been shown that the effective point spread function (PSF) may be manipulated by varying TE or TR, or both, with each phase‐encoding step. This paper explores the behavior of the PSF in a variable TE sequence and its dependence on both imaging and tissue parameters. It is shown that the PSF is different for each tissue type and that its effect on tissue contrast is a function of both the shape and size of the structure. The important problem of signal loss from small objects that arises when the effective PSF is broad and the difficulty in detecting this phenomenon in practical MR images is illustrated. It is shown that the PSF can produce significant blurring and loss of object contrast in fast spin‐echo images but that this blurring may be not be obvious in practice because the noise is unaffected by the PSF. It is also shown that the signal from small lesions with shortT2can easily be lost through this blurring mechanism. The importance of signal loss from small objects and its implication for the clinical use of such sequences as fast spinecho or rapid acquisition relaxation‐enhanced and echo planar imaging is stressed.© 1992 Academic Press,Inc.