Methods of measuring splenic blood flow and platelet transit time with In-111-labeled platelets

Following bolus intravenous injection of In-111-labeled autologous platelets in humans, splenic blood flow (SBF) was measured by compartmental analysis of the equilibration of platelets between blood and the intrasplenic platelet pool. The result correlated closely (r = 0.94, p less than 0.001) with SBF measured from analysis of the first-pass time-activity curve recorded over the spleen by external detection. The intrasplenic platelet transit time (tp), measured concurrently with SBF from compartmental analysis, correlated closely (r = 0.78, p less than 0.001) with tp measured from deconvolution analysis. These correlations appear to support the use of compartmental analysis of the equilibration of radiolabeled platelets between blood and the intrasplenic platelet pool as a valid technique for the simultaneous measurement of SBF and tp. Both of these parameters have potential clinical usefulness for the understanding of intrasplenic platelet kinetics in a variety of disorders.