Mills T C, Ortendahl D A, Hylton N M, Crooks L E, Carlson J W, Kaufman L
Radiology. 1987 Feb;162(2):531-9. doi: 10.1148/radiology.162.2.3797669.
Theoretical analysis predicts that performing magnetic resonance (MR) imaging with partial (less than 90 degrees) flip angles can reduce imaging times two- to fourfold when lesions with elevated T1 values are being examined. This time savings occurs because repetition time (TR) is reduced when imaging is performed with partial flips. Partial flip MR imaging can also improve signal-to-noise ratio (S/N) in fast body imaging. For this study, analytical tools were used to predict image contrast and S/N for short TR, partial flip sequences. Experimental implementation of the short TR, partial flip sequences that analytical work had predicted would be optimal supported the analytical predictions and demonstrated their validity. Partial flip MR imaging is applicable to reducing imaging time only when the ratio of signal differences to noise exceeds threshold values in conventional MR images. Partial flip sequences can be used to advantage in MR imaging of both the head and the body, and the observed effects are predictable through theoretical analysis.
理论分析预测，当检查T1值升高的病变时，使用部分（小于90度）翻转角进行磁共振（MR）成像可将成像时间缩短两至四倍。节省时间的原因是，使用部分翻转进行成像时重复时间（TR）会缩短。部分翻转MR成像还可提高快速体部成像中的信噪比（S/N）。在本研究中，使用分析工具预测短TR、部分翻转序列的图像对比度和S/N。分析工作预测为最佳的短TR、部分翻转序列的实验实施支持了分析预测并证明了其有效性。仅当传统MR图像中信号差异与噪声的比值超过阈值时，部分翻转MR成像才适用于缩短成像时间。部分翻转序列可有效用于头部和体部的MR成像，并且通过理论分析可以预测观察到的效果。
