RAPID REPEAT MEASUREMENT OF RCBF WITH PET AND 0-15 WATER

O-15水，由于其半衰期短，被广泛用于执行 一次扫描会话中的多个连续rCBF测量，例如 功能图谱研究。通常，用户需要等待大约12分钟才能 用于在执行下一次扫描之前的背景衰减。我们有 开发了一种更快速地进行连续rCBF测量的方法， 通过修改示踪剂动力学方程来考虑残留物 上一次扫描的血液和大脑的背景。模拟研究 表明估计中的噪声只增加了2%-3% 由于使用了这种方法，rCBF的变化。已获得初步数据 在休息和视觉刺激期间的受试者中，间隔在 0-15次注水，每次6分钟。残留物的rCBF中的修正百分比 背景从视皮层的6%到白质的17%不等。 已经编写了将这种方法应用于像素上的PET图像的软件- 以像素为单位。这将有助于数据分析比较结果 用这种“快水”方法进行的激活研究 用标准方法测得。此外，我们计划延长这一期限 方法进行半定量0-15水研究，当组织计数为 用于定位激活研究中的rCBF变化。 这种增加rCBF测量频率的方法将提供 在脑成像和研究等正电子发射计算机断层扫描实验中具有更大的灵活性 急性药物对局部脑血流量的影响。此外，它还将使此类研究变得更容易 让病人忍耐。它将在三维成像研究中发挥作用。 单一受试者，其中更多的注射较小数量的0-15 用水来提高信噪比。

O-15 water, because of its short half-life, is widely used to perform multiple sequential rCBF measurements in one scan session, e.g., in functional mapping studies. Typically, one waits about 12 min to allow for decay of the background before performing the next scan. We have developed a method to perform sequential rCBF measurements more rapidly, by modifying the tracer kinetic equation to account for residual background in blood and brain from a previous scan. Simulation studies demonstrated that there is only a 2-3% increase in the noise in estimates of rCBF due to use of this method. Preliminary data have been obtained in subjects at rest and during visual stimulation, with intervals between 0-15 water injections of 6 min. The % correction in rCBF for residual background ranged from 6% in visual cortex to 17% in white matter. Software has been written to apply this method to PET images on a pixel- by-pixel basis. This will facilitate data analysis comparing the results of activation studies performed with this "fast water" approach to those obtained with the standard method. In addition, we plan to extend this method to semiquantitative 0-15 water studies, when tissue counts are used to map rCBF changes in activation studies. This approach to increase the frequency of rCBF measurements will provide greater flexibility in PET experiments such as brain mapping and studies of acute drug effects on rCBF. Also, it will make such studies easier for patients to tolerate. It will be useful in 3-D imaging studies of single-subjects, in which many more injections of smaller amounts of 0-15 water are used to increase signal-to-noise ratio.