[New analysis algorithm for regional cerebral blood flow and partition coefficient with dynamic SPECT and N-isopropyl-p-[123I]iodoamphetamine: graphical plot method].

We developed a new analysis algorithm based on multiple-time graphical plot to estimate the regional cerebral blood flow and partition coefficient using dynamic SPECT and N-isopropyl-p-[123I]iodoamphetamine (123I-IMP). By assuming the 2-compartment model of the kinetic for 123I-IMP, we derived a linear relationship between the ratio of the tissue activity concentration at the times to the time-integral arterial concentration at the respective times (formula; see text) and the ratio of the time-integral tissue concentration to the time-integral arterial concentration (formula; see text), and demonstrated that the Y-intercept and X-intercept of the plot line represent the regional cerebral blood flow (K1) and partition coefficient (lambda), respectively. The slope of the line represents a clearance constant k2. The present method was applied to data on four normal subjects measured by dynamic SPECT. Values of the K1 and lambda for the gray matter were obtained 40.8 +/- 6.5 ml/100 g/min and 28.8 +/- 5.3 ml/g, respectively, and the corresponding values for the white matter were 29.1 +/- 4.7 ml/100 g/min and 28.1 +/- 7.1 ml/g. The new method enabled a rapid estimation of both K1 and lambda.