Cordes M, Snow B J, Morrison S, Sossi V, Ruth T J, Calne D B
Neurodegenerative Disorders Centre, University Hospital, University of British Columbia, Vancouver, Canada.
Neuroradiology. 1993;35(6):404-9. doi: 10.1007/BF00602816.
Positron emission tomography (PET) studies using [18F]-L-dopa were carried out in 9 patients with supranuclear palsy and 13 controls. For quantification of PET data a rate constant Ki was calculated for the radiotracer using a graphical method. Corrections for nonspecific activity were performed in both arterial plasma and brain tissue. The purpose of this study was to test the hypothesis that parametric images of the rate constant K mapping can be obtained on a pixel-by-pixel basis using an appropriate mathematical algorithm. Ki values from these parametric images and the graphical approach were compared. Both correlated closely, with y = 0.013 + 0.947x, r = 0.992 and y = -0.052 + 1.018x, r = 0.965 in patients and controls, respectively. Contrast measurements were also performed and showed a striking increase in contrast on parametric images. K mapping offers several advantages over the graphical approach, since parametric images are time-independent, i.e. one image represents the quantitative result of the study. In addition, parametric images of the rate constant are normalized to arterial plasma radioactivity and corrected for tissue metabolites. Thus, parametric images of Ki in different individuals can be compared directly without further processing in order to assess the nigrostriatal integrity.
使用[18F]-L-多巴对9例核上性麻痹患者和13名对照者进行了正电子发射断层扫描（PET）研究。为了对PET数据进行定量分析，使用图形方法计算了放射性示踪剂的速率常数Ki。对动脉血浆和脑组织中的非特异性活性进行了校正。本研究的目的是检验这样一个假设，即使用适当的数学算法可以逐像素获得速率常数K映射的参数图像。比较了这些参数图像的Ki值和图形方法的结果。两者密切相关，患者和对照者的相关方程分别为y = 0.013 + 0.947x，r = 0.992和y = -0.052 + 1.018x，r = 0.965。还进行了对比度测量，结果显示参数图像的对比度显著增加。与图形方法相比，K映射具有几个优点，因为参数图像与时间无关，即一幅图像代表研究的定量结果。此外，速率常数的参数图像已根据动脉血浆放射性进行了归一化，并对组织代谢物进行了校正。因此，不同个体的Ki参数图像可以直接比较，无需进一步处理即可评估黑质纹状体的完整性。
