Using the spleen for time-delay correction of the input function in measuring hepatic blood flow with oxygen-15 water by dynamic PET

By the spleen, we calculated a time-delay correction of the input function for quantitation of hepatic blood flow with oxygen-15 water and dynamic pos itron emission tomography. The time delay (Delta t) between the sample site and the spleen was calculated based on nonlinear multiple regression analy sis when splenic blood flow was determined. Then hepatic blood flow was qua ntified by a method using the input function and incorporating Delta t, whi ch was assumed to be equal to the time delay between the sample site and th e liver. Then hepatic arterial and portal blood flows were estimated separa tely as well as the delay time for passage within the organs of the portal circulation. The mean coefficient of variation and the mean sum of squares of errors decreased to about 70% when total hepatic blood flow was calculat ed from the results for regions of interest in three slices of the same liv er segment. We concluded that using the spleen for time-delay correction of the input function for measuring hepatic blood flow by this method gave sa tisfactory results.