STRATEGIES TO IMPROVE CONTRAST IN TURBOFLASH IMAGING - REORDERED PHASE ENCODING AND K-SPACE SEGMENTATION
STRATEGIES TO IMPROVE CONTRAST IN TURBOFLASH IMAGING - REORDERED PHASE ENCODING AND K-SPACE SEGMENTATION
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DOI：
10.1002/jmri.1880010108
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发表时间：
1991-01-01
期刊：
影响因子：
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通讯作者：
EDELMAN, RR
中科院分区：
文献类型：
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作者：
CHIEN, D;ATKINSON, DJ;EDELMAN, RR
TurboFLASH（快速低角度拍摄）序列可以在几分之一秒内获取图像。然而，对于t1加权超快速成像来说，图像采集过程中的磁化变化会沿相位编码方向产生伪影。在本研究中，通过各种采集方案分析了这些伪影的信号行为和性质，以提高图像对比度。采用三种不同的t1加权turboFLASH成像方法模拟了图像采集过程中的磁化变化及其对图像的滤波效果：采用(a)单调递增的相位编码步骤的标准turboFLASH， (b)重排序的相位编码，以及(c) k空间分割。每种改进的数据采集方案都有其优点。然而，对于亚秒成像，重新排序的相位编码比标准的turboFLASH产生了更好的图像对比度，与标准和重新排序的turboFLASH相比，分割的k空间成像提供了更好的组织对比度，成像时间允许屏气研究。
TurboFLASH (fast low-angle shot) sequences enable the acquisition of an image in a fraction of a second. However, unique to T1-weighted ultra-fast imaging, the magnetization variation during image acquisition can produce artifacts along the phase-encoding direction. In this study, the signal behavior and nature of these artifacts were analyzed with various acquisition schemes to improve image contrast. The magnetization variation during image acquisition and its filtering effect on the image were simulated for three different approaches to T1-weighted turboFLASH imaging: standard turboFLASH with (a) monotonically ascending phase-encoding steps, (b) reordered phase encoding, and (c) k-space segmentation. Each of the modified data acquisition schemes has advantages. However, for subsecond imaging, reordered phase encoding produced improved image contrast over that of standard turboFLASH, and segmented k-space imaging gave superior tissue contrast compared with that of both standard and reordered turboFLASH, with imaging time that permits breath-hold studies.