Piraino D W, Hardy P A, Schils J P, Richmond B J, Tkach J A, Belhobek G H
Department of Radiology A-21, Cleveland Clinic Foundation, OH 44195.
J Magn Reson Imaging. 1993 Nov-Dec;3(6):835-42. doi: 10.1002/jmri.1880030606.
Conventional T2-weighted spin-echo magnetic resonance imaging of the knee requires a long TR. Fast spin-echo (FSE) imaging can improve acquisition efficiency severalfold by collecting multiple lines of k space for each TR. Compromises in resolution, section coverage, and contrast inevitably result. The authors examined the compromises encountered in FSE imaging of the knee and discuss the variations in image contrast and resolution due to choices of sequence parameters. For short TR/TE knee imaging, FSE does not appear to offer any advantages, since the increased collection efficiency for one section reduces the available number of sections, so that the total imaging time for a given number of sections remains constant relative to conventional spin-echo imaging. For T2-weighted images, considerable time can be saved and comparable quality images can be obtained. This saved time can be usefully spent on increasing both the resolution of the image and its signal-to-noise ratio, while still reducing total acquisition time by a factor of two. The preferred FSE T2-weighted images were acquired with a TR of 4,500 msec, TE of 120 msec, and eight echoes. The available number of sections is compromised, and the sequence remains sensitive to flow artifacts; however, the FSE sequence appears to be promising for knee imaging.
膝关节的传统T2加权自旋回波磁共振成像需要较长的重复时间（TR）。快速自旋回波（FSE）成像通过在每个TR期间采集多条k空间线，可将采集效率提高数倍。但不可避免地会在分辨率、层面覆盖范围和对比度方面有所妥协。作者研究了膝关节FSE成像中遇到的这些妥协情况，并讨论了由于序列参数选择导致的图像对比度和分辨率的变化。对于短TR/TE的膝关节成像，FSE似乎没有任何优势，因为一个层面增加的采集效率会减少可用的层面数量，所以对于给定数量的层面，相对于传统自旋回波成像，总成像时间保持不变。对于T2加权图像，可以节省大量时间并获得质量相当的图像。节省的这些时间可以有效地用于提高图像的分辨率及其信噪比，同时仍可将总采集时间缩短一半。首选的FSE T2加权图像是在TR为4500毫秒、TE为120毫秒且有八个回波的条件下采集的。可用的层面数量会受到影响，并且该序列对流动伪影仍很敏感；然而，FSE序列在膝关节成像方面似乎很有前景。
