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 (99m Tc-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 99m Tc-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, K r GSA.

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 K r GSA.

RESULTS: K r GSA values accurately identified liver cirrhosis and were similar to the KICG. The areas under the curve for K r GSA and KICG in the receiver operating characteristic analysis were 0.808 and 0.795, respectively, and a good correlation was seen between K r GSA and KICG.

DISCUSSION/CONCLUSION: K r GSA can be utilized as an alternative to KICG in assessing the future liver remnant function.