Wright G A, Hu B S, Macovski A
Magnetic Resonance Systems Research Laboratory, Stanford University, CA 94305.
J Magn Reson Imaging. 1991 May-Jun;1(3):275-83. doi: 10.1002/jmri.1880010303.
The use of magnetic resonance (MR) imaging is investigated for noninvasively estimating the oxygen saturation of human blood (%HbO2) in vivo by means of relaxation characteristics identified in earlier MR spectrometry studies. To this end, a sequence is presented for determining the T2 of vascular blood in regions in which motions of the body and of the blood itself present a major challenge. With use of this sequence on a commercial 1.5-T whole-body imager, the relationship between the T2 and %HbO2 of blood is calibrated in vitro for the conditions expected in vivo. T2 varies predictably from about 30 to 250 msec as %HbO2 varies from 30% to 96%. T2 values measured in situ for vascular blood in the mediastinum of several healthy subjects qualitatively reflected the behavior observed in vitro. Estimates of %HbO2 for these vessels obtained with the in vitro calibration appear reasonable, particularly for venous blood, although difficulties arise in selecting the appropriate calibration factors. These encouraging initial results support a more systematic study of potential sources of error and an examination of the accuracy of in vivo measurements by comparison with direct measurements of %HbO2 in vessels.
通过早期磁共振波谱研究中确定的弛豫特性，对磁共振（MR）成像用于无创估计人体血液中氧饱和度（%HbO2）的体内情况进行了研究。为此，提出了一种用于确定身体运动和血液自身运动构成主要挑战的区域中血管血液T2的序列。在商用1.5-T全身成像仪上使用该序列，针对体内预期的条件在体外校准血液的T2与%HbO2之间的关系。当%HbO2从30%变化到96%时，T2可预测地从约30毫秒变化到250毫秒。在几名健康受试者纵隔中对血管血液原位测量的T2值定性地反映了体外观察到的行为。使用体外校准获得的这些血管的%HbO2估计值似乎是合理的，特别是对于静脉血，尽管在选择合适的校准因子时出现了困难。这些令人鼓舞的初步结果支持对潜在误差源进行更系统的研究，并通过与血管中%HbO2的直接测量结果进行比较来检查体内测量的准确性。
