St Lawrence K S, Lee T Y
Department of Diagnostic Radiology and the Lawson Research Institute, St. Joseph's Health Centre, London, Ontario, Canada.
J Cereb Blood Flow Metab. 1998 Dec;18(12):1378-85. doi: 10.1097/00004647-199812000-00012.
A frequently reported limitation to using water as a tracer for measuring CBF has been the dependence of the CBF estimate on the experimental time (referred to as the falling flow phenomenon, FFP). To eliminate the FFP, we have developed the adiabatic solution of the tissue homogeneity model to replace the solution of the single-compartment Kety model. In Part I, the derivation of the adiabatic solution was presented. In this second part, the adiabatic solution was applied to measure CBF in rabbits using nuclear magnetic resonance spectroscopy and the tracer deuterium oxide. It was shown that the FFP, observable when the 2H clearance data were analyzed with the Kety equation, was significantly reduced when the same data were analyzed with the adiabatic solution of the tissue homogeneity model. By concurrently measuring CBF with radioactive microspheres, it was determined that the CBF estimates from the adiabatic solution were accurate for true blood flow values less than 60 mL x 100 g(-1) x min(-1). Above this value the CBF estimate was progressively underestimated, which was attributed to the diffusion limitation of water in the brain.
使用水作为示踪剂来测量脑血流量（CBF）时，一个经常被报道的限制是CBF估计值对实验时间的依赖性（称为下降流现象，FFP）。为了消除FFP，我们开发了组织均匀性模型的绝热解来替代单室凯蒂模型的解。在第一部分中，介绍了绝热解的推导。在这第二部分中，绝热解被应用于使用核磁共振光谱和示踪剂氧化氘测量兔子的CBF。结果表明，当用凯蒂方程分析2H清除数据时可观察到的FFP，在用组织均匀性模型的绝热解分析相同数据时显著降低。通过同时用放射性微球测量CBF，确定对于小于60 mL×100 g⁻¹×min⁻¹的真实血流值，绝热解得出的CBF估计值是准确的。高于此值时，CBF估计值逐渐被低估，这归因于水在大脑中的扩散限制。
