Vinitski S, Mitchell D G, Rifkin M D, Burk D L
Department of Radiology/MRI, Jefferson Medical College, Thomas Jefferson University Hospital, Philadelphia, PA 19107.
J Comput Assist Tomogr. 1989 Nov-Dec;13(6):1041-7. doi: 10.1097/00004728-198911000-00017.
Narrow bandwidth magnetic resonance (MR) imaging allows an increase of signal-to-noise ratio (SNR) but causes increased chemical shift and motion-induced artifacts. To obtain MR images with SNR approximately equal to that obtained with narrow bandwidth but with less chemical shift and motion-induced artifact, we introduced triple readout gradient reversal centered around the spin echo. As a result, signals from two gradient echoes and a single spin echo can be collected and summed. Phantom, knee, shoulder, and abdominal MR images were obtained using a 1.5 T GE Signa System at sampling rates ranging from 10 to 60 kHz. Since the bandwidth per pixel was tripled, chemical shift misregistration was reduced by the same factor. The summation image of two gradient echoes and one spin echo had an SNR comparable with that of a single spin echo acquired within the same total sampling interval. Data acquisition at a high sampling ratio also minimizes the dispersion of T2* weighting among three echoes. In addition, summation of the three resulting images decreases motion artifact by effective averaging.
窄带宽磁共振（MR）成像可提高信噪比（SNR），但会导致化学位移和运动诱导伪影增加。为了获得信噪比与窄带宽成像近似，但化学位移和运动诱导伪影更少的MR图像，我们引入了以自旋回波为中心的三重读出梯度反转。结果，可以采集并叠加来自两个梯度回波和一个自旋回波的信号。使用1.5 T GE Signa系统，以10至60 kHz的采样率获取了体模、膝盖、肩膀和腹部的MR图像。由于每个像素的带宽增加了两倍，化学位移配准误差也相应减少了相同倍数。两个梯度回波和一个自旋回波的叠加图像的信噪比与在相同总采样间隔内采集的单个自旋回波相当。高采样率下的数据采集还可将三个回波之间T2*加权的离散度降至最低。此外，对所得的三张图像进行叠加可通过有效平均减少运动伪影。
