ACCURATE LOCAL BLOOD-FLOW MEASUREMENTS WITH DYNAMIC PET - FAST DETERMINATION OF INPUT FUNCTION DELAY AND DISPERSION BY MULTILINEAR MINIMIZATION

Accurate determination of local blood flow in tissue using the Kety-Sc hmidt one-compartment model for freely diffusible tracers requires kno wledge of the true arterial input function in tissue. Because measured input functions are usually delayed and dispersed with respect to tru e influx, a correction of the experimental input function is necessary . We describe a technique that uses a fast multilinear least-squares m inimization procedure to determine simultaneously the dispersion, the blood flow and the partition coefficient as a function of delay. In th is approach, a few multilinear fits are sufficient to determine the co mplete set of parameters necessary to describe the data. Because of th e high speed of the procedure, dispersion effects may be taken into ac count on a pixel-by-pixel basis in calculating parametric images of bl ood flow and partition coefficient. The described procedure has been u sed at our institute for about 1 yr in more than 160 investigations an d has proven well suited for routine use in a clinical environment.