PHYSICAL BASIS FOR DIAGNOSTIC 19F MR IMAGING

这个项目的目标是开发研究血液的方法。 磁共振脑血流灌注和氧分压的研究 氟化血液替代品(FBS)的成像(MRI)，以及 将结果与使用几种技术获得的结果进行比较 已经提出了使用质子磁共振的方法。主要问题是 检测血流量的可能性和可取性 微血管水平，即小动脉、毛细血管和小静脉。 传统的质子核磁共振成像存在的主要问题是 大多数质子自旋来自血管外的水，所以 要获得对静止自旋的充分抑制是困难的。 此外，到目前为止，大多数质子磁共振流动研究都集中在 检测主要血管中的流量，以及可能能够 对微血管血流的检测仍处于萌芽阶段。因此，目前， 这些质子磁共振灌注技术的有效性是 有问题。氟19胎牛磁共振成像具有独特的优势， 核磁共振信号只来自血管系统，所以 不存在抑制静态自旋的问题。此外， 我们以前的工作表明，FBS MRI可以用来标测 活体平均血管氧分压。我们解决的问题是 HCW将使FBS MRI对微血管中的流动现象敏感 水平，即速度低于1毫米每秒。 我们还解决了区分时间依赖关系的问题 由于流动诱导洗入/洗出现象而产生的MRI信号 氧诱导的T1弛豫具有时间依赖性。我们建议 比较不同年龄组局部血流量的MRI定量测量结果 猫脑，用既定的技术进行测量 放射性微球。我们还提出了定性的假设 微血管速度场与微血管速度场的比较 使用14-C LAP的放射自显影进行了演示。这些结果将 与几种已提出的毛细管流成像技术的比较 使用质子核磁共振。作为我们以前在这方面工作的延续 我们打算评估更多的氟碳化合物在我们的 寻找需要改进的生物学和物理特性 做FBS核磁共振检查。

The goal of this project is to develop methods for studying blood perfusion and oxygen tension in the brain using magnetic resonance imaging (MRI) of fluorinated blood substitutes (FBS), and to compare the results with those obtained using several techniques which have been proposed using proton MRI. The major issue is the possibility and desirability of detecting blood flow at the microvessel level, i.e., arterioles, capillaries, and venules. Conventional proton MRI has the major problem that the overwhelming majority of the proton spins come from extravascular water, so that getting adequate suppression of the stationary spins is difficult. Furthermore, most proton MRI flow studies to date have focussed on detecting flow in the major vessels, and methods which may be able to detect microvessel flow are still embryonic. Hence, at present the validity of these proton MRI perfusion techniques is questionable. Fluorine 19 FBS MRI has the unique advantage that the MRI signal comes only from the vascular system, so that the problem of suppressing static spins does not exist. Furthermore, our previous work has shown that FBS MRI can be used to map the mean vascular oxygen tension in vivo. We address the problem of hcw to make FBS MRI sensitive to flow phenomena at the microvessel level, i.e., with velocities less than 1 millimeter per second. We also address the problem of distinguishing the time dependence of the MRI signal due to flow induced washin/washout phenomena from the time dependence of oxygen induced T1 relaxation. We propose to compare quantitative MRI measurements of local blood flow in the cat brain with measurements made using the established technique of radioactive microspheres. We also prcpose qualitative comparison of the microvessel flow velocity field with that demonstrated using autoradiography of 14-C LAP. These results will be compared with several proposed echniques to image caillary flow using proton MRI. As a continuation of our previous work in this field, we intend to evaluate more fluorocarbon compounds in our search for improved biological and physical characteristics needed for FBS MRI.