Dhawan V, Jarden J O, Moeller J R, Strother S C, Rottenberg D A
Department of Neurology, Memorial Sloan-Kettering Cancer Center, New York, NY 10021.
Phys Med Biol. 1989 Dec;34(12):1785-94. doi: 10.1088/0031-9155/34/12/003.
Computer simulations and error analysis of a simple two-compartment, passive-diffusion exchange model for 82Rb across the blood-brain-barrier (BBB) have demonstrated the feasibility of obtaining useful estimates of unidirectional rate constant (K1) and tissue-blood water volume (Vb) in vivo using dynamic positron tomography (PET). The coefficients of variation (CV) in parameter estimates for 20 studies on ten patients are shown to have mean values of 10% for tumour K1 and Vb, 6% for normal brain Vb and 30% for normal brain K1. Ten test-retest studies show a very high correlation (R2 greater than 0.88) between the estimated parameter values. Apparent tissue blood volume (Vb) estimates obtained from 82Rb studies underestimate the blood volumes obtained by single-breath C15O studies by approximately 15%. In normal brain the extraction of rubidium (E) is small (less than 10%), and gives rise to a linear relationship between K1 and permeability-surface area product (PS). In tumour, however, E is larger (greater than 30%), and results in a non-linear relationship between these values. For both tumour and normal brain, K1 was found to be independent of regional cerebral blood flow (rCBF). The data from these clinical studies are in agreement with the predictions of the computer simulations and suggest the suitability of 82Rb/PET in the quantification of BBB functional changes.
针对82Rb通过血脑屏障（BBB）的简单双室被动扩散交换模型进行的计算机模拟和误差分析表明，使用动态正电子断层扫描（PET）在体内获得单向速率常数（K1）和组织血容量（Vb）的有用估计值是可行的。对10名患者进行的20项研究中参数估计值的变异系数（CV）显示，肿瘤K1和Vb的平均值为10%，正常脑Vb为6%，正常脑K1为30%。十次重测研究表明，估计的参数值之间具有非常高的相关性（R2大于0.88）。从82Rb研究中获得的表观组织血容量（Vb）估计值比单次呼吸C15O研究获得的血容量低估了约15%。在正常脑中，铷的摄取量（E）很小（小于10%），并导致K1与通透表面积乘积（PS）之间呈线性关系。然而，在肿瘤中，E较大（大于30%），并导致这些值之间呈非线性关系。对于肿瘤和正常脑，均发现K1与局部脑血流量（rCBF）无关。这些临床研究的数据与计算机模拟的预测结果一致，并表明82Rb/PET适用于定量BBB功能变化。
