A new method for quantitative measurement of rCBF using graphic plot analysis

To estimate regional cerebral blood flow (rCBF) using the dynamic data, a new graphic plot analysis is proposed. By assuming a two-compartment model for the tracer kinetics, we derived the linear relationship as Y(t)=1/K1+Θt, where Y(t) is the ratio of time-integrated blood activity to brain tissue activity, t is the scan time, and Θ is a proportional constant. A plot of Y(t) against the scan time t yields a straight line and the y-intercept of the line represents the value of inverse rCBF K1. This method was applied to five normal subjects with N-isopropyl-p(123I)iodoamphetamine. The mean value of K1 in the gray matter was 42.1±6.8 ml/100g/min. We also produced the rCBF images within a few seconds using the present method. The present graphical method gives a reliable and rapid estimation of rCBF. (author)