Usefulness of Liver Uptake Rate Constant in (99m)Tc-GSA Scintigraphy for the Risk Stratification of Patients Undergoing Hepatectomy: A New Method for Calculation

INTRODUCTION: The use of technetium 99m diethylenetriaminepentaacetic acid-galactosyl human serum albumin (^99mTc-GSA) scintigraphy parameters, HH15 and LHL15, in assessing the future liver remnant function is not expedient because of their nonlinear behaviour against liver volume. Uptake rate constant for the binding of ^99mTc-GSA to asialoglycoprotein receptors is probably more favourable, but the reported calculation methods are complex. We devised a simple method to calculate the uptake rate constant, KrGSA. METHODS: Radioactivity counts for the entire liver and heart regions were extracted at 10, 20, and 30 min. Using whole liver and heart volumes measured from single-photon emission computed tomography images, free radioactivity corresponding to the liver blood pool was subtracted. The time activity curve was fitted to the equation L(t) = L(∞) × [1 − Exp (−kt)] using Microsoft Office Excel (add-in free programme Solver)®, where L(∞) is the count at plateau level and k denotes KrGSA. RESULTS: KrGSA values accurately identified liver cirrhosis and were similar to the KICG. The areas under the curve for KrGSA and KICG in the receiver operating characteristic analysis were 0.808 and 0.795, respectively, and a good correlation was seen between KrGSA and KICG. DISCUSSION/CONCLUSION: KrGSA can be utilized as an alternative to KICG in assessing the future liver remnant function.