Fast two-compartment model analysis with 99mTc-GSA liver scintigraphy

The use of a numerical integration method (N.INT) was evaluated in determining parameters by two-compartment model analysis from liver scintigraphy. Among the 15 subjects, 14 had liver cirrhosis or chronic hepatitis, and one was normal. When using N.INT, the sum of two exponential functions on heart regression curve following intravenous injection of 99mTc-galactosyl human serum albumin (99mTc-GSA) was promptly calculated. The parameters obtained from N.INT, including transfer rate of 99mTc-GSA from extrahepatic blood to liver (k1), dissociation rate from liver to extrahepatic blood (k2), and excretion rate from liver to gallbladder (k3), were significantly correlated with those obtained by the nonlinear least square method (NLS). k1/k2 was related with the maximum removal rate of 99mTc-GSA obtained from nonlinear five compartment model analysis (r2=0.705, n=15) and also with the severity score of liver disease as classified by the First Department of Surgery, Mie University Medical School (r2=0.686, n=13). In terms of the time required to obtain these parameters, including the blood retention rate of 99mTc-GSA at 15 min after injection (%ID15), N.INT was faster than the traditional method (NLS). (author)