[A new method for pharmacokinetic analysis of 99mTc-GSA using two-compartment and two-parameter model]

Technetium-99m-diethylenetriaminepentaacetic acid-galactosyl-human serum albumin (99mTc-GSA) is a liver scintigraphy agent which binds to asialoglycoprotein receptor in hepatocyte. Twenty-six patients with liver dysfunction were examined with 99mTc-GSA liver scintigraphy using two-compartment and two-parameter model (2C2P model). The 99mTc-GSA was assumed to move within two compartments (whole blood and liver). k1 and k2 were parameters which represented transfer rate constant from blood to liver, and from liver to blood, respectively. Two differential equations based on 2C2P model were integrated, so that k1, k2, k1/k2 and VLmg were estimated from the time-activity curves of the heart and liver. VLmg was computed as maximum amount of 99mTc-GSA binding to liver. The results were compared with the liver function tests and the conventional 99mTc-GSA indices: HH15, LHL15, and LU15. k1/k2 and VLmg values had positive correlation with the result of the serum liver function tests, Plt., T.Bil., ChE, GOT, LDH, ALP and gamma GTP. It is concluded that this new method using 2C2P model is not invasive and simplest in the 99mTc-GSA liver scintigraphies, and may be useful in evaluating liver function.