Jones Richard A, Ries Mario, Moonen Chrit T W, Grenier Nicolas
RMSB, CNRS/Universite Bordeaux 2, Bordeaux, France.
Magn Reson Med. 2002 Apr;47(4):728-35. doi: 10.1002/mrm.10127.
The effect of the inhalation of pure oxygen on the kidney was evaluated by measuring monoexponential T1 and T2* relaxation times in nine volunteers using a multiple-shot turbo spin echo and multiple echo gradient echo sequences, respectively. The T1 of the renal cortex decreased significantly when breathing pure oxygen as compared to normoxia (from 882 +/- 59 to 829 +/- 70 msec, P < 0.05), while that of the renal medulla was unchanged. No significant changes were seen in the T2* of either compartment. Dynamic imaging using an inversion recovery sequence with an optimized inversion time typically produced signal changes of 20% in the renal cortex. Studies to assess if oxygen-induced changes in flow contributed to this effect showed that the flow contribution was not significant. Although longer inversion times (880 ms) produced optimal contrast, acceptable contrast was also obtained at shorter inversion times (450 msec) in the renal cortex, spleen, and lung, with the latter being of opposite polarity to the other two tissues, implying a shorter parenchymal T1 than previously reported in the literature. The results are consistent with oxygen acting as an intravascular contrast agent which induces a shortening of T1 in the arterial blood volume.
通过分别使用多次激发快速自旋回波序列和多回波梯度回波序列测量9名志愿者的单指数T1和T2弛豫时间，评估吸入纯氧对肾脏的影响。与常氧状态相比，呼吸纯氧时肾皮质的T1显著降低（从882±59毫秒降至829±70毫秒，P<0.05），而肾髓质的T1则无变化。两个区域的T2均未见显著变化。使用具有优化反转时间的反转恢复序列进行动态成像，通常在肾皮质中产生20%的信号变化。评估氧气诱导的血流变化是否导致这种效应的研究表明，血流贡献不显著。尽管较长的反转时间（880毫秒）产生了最佳对比度，但在肾皮质、脾脏和肺中，较短的反转时间（450毫秒）也获得了可接受的对比度，其中肺的对比度极性与其他两个组织相反，这意味着实质T1比文献中先前报道的更短。这些结果与氧气作为血管内造影剂导致动脉血容量中T1缩短的作用一致。
