Stroman P W, Krause V, Frankenstein U N, Malisza K L, Tomanek B
MR Technology Group, Institute for Biodiagnostics, National Research Council of Canada, Winnipeg, Manitoba, Canada.
Magn Reson Imaging. 2001 Jul;19(6):827-31. doi: 10.1016/s0730-725x(01)00392-7.
Blood-oxygen level dependent signal changes in the visual cortex were investigated as a function of echo time with spin-echo and gradient-echo EPI at 1.5 T and 3 T. The linear relationship between the fractional signal change and the echo time was apparent in all cases. Relaxation rate changes determined from the slope of this linear relation agree with published values, intercept values extrapolated to an echo time of zero, however, were 0.66% to 1.0% with spin-echo EPI, and 0.11% to 0.35% with gradient-echo EPI. Spin-echo and gradient-echo EPI can therefore yield similar signal changes at sufficiently short echo times.
在1.5T和3T场强下，利用自旋回波和梯度回波EPI技术，研究了视觉皮层中血氧水平依赖信号变化与回波时间的函数关系。在所有情况下，分数信号变化与回波时间之间的线性关系都很明显。根据该线性关系斜率确定的弛豫率变化与已发表的值一致，然而，自旋回波EPI外推到零回波时间的截距值为0.66%至1.0%，梯度回波EPI的截距值为0.11%至0.35%。因此，在足够短的回波时间下，自旋回波和梯度回波EPI可以产生相似的信号变化。
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