Ronen I, Merkle H, Ugurbil K, Navon G
School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel.
Proc Natl Acad Sci U S A. 1998 Oct 27;95(22):12934-9. doi: 10.1073/pnas.95.22.12934.
Imaging of H217O has a number of important applications. Mapping the distribution of H217O produced by oxidative metabolism of 17O-enriched oxygen gas may lead to a new method of metabolic functional imaging; regional cerebral blood flow also can be measured by measuring the H217O distribution after the injection of 17O-enriched physiological saline solution. Previous studies have proposed a method for indirect detection of 17O. The method is based on the shortening of the proton T2 in H217O solutions, caused by the residual 17O-1H scalar coupling and transferred to the bulk water via fast chemical exchange. It has been shown that the proton T2 of H217O solutions can be restored to that of H216O by irradiating the resonance frequency of the 17O nucleus. The indirect 17O image thus is obtained by taking the difference between two T2-weighted spin-echo images: one acquired after irradiation of the 17O resonance and one acquired without irradiation. It also has been established that, at relatively low concentrations of H217O, the indirect method yields an image that quantitatively reflects the H217O distribution in the sample. The method is referred to as PRIMO (proton imaging of oxygen). In this work, we show in vivo proton images of the H217O distribution in a rat brain after an i.v. injection of H217O-enriched physiological saline solution. Implementing the indirect detection method in an echo-planar imaging sequence enabled obtaining H217O images with good spatial and temporal resolution of few seconds.
H₂¹⁷O成像有许多重要应用。绘制由富集¹⁷O的氧气氧化代谢产生的H₂¹⁷O的分布情况，可能会带来一种新的代谢功能成像方法；通过测量注射富集¹⁷O的生理盐水溶液后的H₂¹⁷O分布，还可以测量局部脑血流量。先前的研究提出了一种间接检测¹⁷O的方法。该方法基于H₂¹⁷O溶液中质子T₂的缩短，这是由残余的¹⁷O-¹H标量耦合引起的，并通过快速化学交换转移到主体水中。研究表明，通过照射¹⁷O核的共振频率，H₂¹⁷O溶液的质子T₂可以恢复到H₂¹⁶O的质子T₂。因此，间接¹⁷O图像是通过获取两个T₂加权自旋回波图像之间的差值得到的：一个是在¹⁷O共振照射后采集的，另一个是在未照射时采集的。还已经确定，在相对低浓度的H₂¹⁷O下，间接方法产生的图像能够定量反映样品中H₂¹⁷O的分布。该方法被称为PRIMO（氧的质子成像）。在这项工作中，我们展示了静脉注射富集H₂¹⁷O的生理盐水溶液后大鼠脑中H₂¹⁷O分布的体内质子图像。在回波平面成像序列中实施间接检测方法，能够获得具有几秒良好空间和时间分辨率的H₂¹⁷O图像。
