Preoperative evaluation of hepatic functional reserve by converted ICGR15 calculated from Tc-GSA scintigraphy

Conversion of data from technetium 99 m diethylenetriaminepentaacetic acid galactosyl human serum albumin (99mTc-GSA) scintigraphy to ICGR15 (indocyanin green retention at 15 min) is an easy and convenient method for obtaining parameters to determine the appropriate and safe extent of liver resection. We investigated a conversion method which also accounts for LHL15 (receptor index: uptake ratio of the liver to the liver plus heart at 15 min) and HH15 (blood clearance index: uptake ratio of the heart at 15 min to that at 3 min) characteristics.

Cases included 282 patients undergoing hepatic resection following 99mTc-GSA scintigraphy and an ICG tolerance test. Degree of liver dysfunction was classified as A, B, or C according to criteria of the Liver Cancer Study Group of Japan.

HH15 demonstrated a larger distribution in patients with liver damage A, while LHL15 demonstrated a larger distribution in patients with liver damage B. In liver damage A, the conversion formula ICGR15 = 87.0-79.6 x LHL15 was obtained, and in liver damage B, the conversion formula ICGR15 = -23.3 + 72.4 x HH15 was obtained, and correlation with ICGR15 was higher (r = 0.61, P < 0.0001) than when the data were not segregated by liver damage severity. Furthermore, postoperative hyperbilirubinemia significantly occurred in cases where both ICGR15 and converted ICGR15 were high.

Conversion models based on data segregated by severity of liver damage were more closely correlated with ICGR15 than conversion models not based on segregated data. By using this converted ICGR15, preoperative estimation of hepatic functional reserve can become more reliable.