The role of proportionate kinetic growth rate fraction in future remnant liver function using 99mTc-Mebrofenin hepatobiliary scintigraphy versus future remnant liver volume to predict postoperative mortality in ALPPS

Background: ALPPS (Associating Liver Partition and Portal Vein ligation for Staged Hepatectomy) has been associated with a disproportionate volumetric versus a functional increase in the future remnant liver (FRL). The aim of our study is to quantify these changes, using 99mTc-mebrofenin hepatobiliary scintigraphy with SPECT-CT (HBS) and CT volumetric measurements respectively against the postoperative outcome. Materials & Methods: Consecutive patients (Jan -Dec 2015) who met the criteria for the ALPPS procedure were included in this retrospective case series. They underwent CT volumetric measurement and HBS scans of the FRL before and 2 weeks after the first step of the ALPPS procedure (ALPPS1). Change in volume and function were compared pre- and post ALPPS1. A cut-off value for completion hepatectomy was set for future remnant liver function (RLF) at 2.7%/min/m2 and a minimal 30% future remnant liver volume ratio (RLV) was required. Kinetic growth rate per day (KGR) and proportionate KGR relative to the pre-ALPPS1 value were calculated and compared for RLF and RLV, respectively. The proportionate KGR fraction of RLF over RLV was used as a parameter when comparing postoperative mortality. Results: In 5 patients, the mean relative increase from baseline (pre-ALPPS1) was 98.1% for RLV and 48.7% for RLF respectively. One patient did not undergo completion hepatectomy because of insufficient RLF (2.1%/min/m2). The proportionate KGR function over volume fraction was below 0.6 with an RLV above 30% and RLF above 2.7%/min/m2 for those who underwent ALPPS successfully without postoperative mortality. Conclusion: The rate at which the function increases is half of that of the volume increase rate in patients undergoing the ALPPS procedure successfully without mortality. Proportionate KGR function over volume might be applicated as a useful quantitative tool to measure this relation but needs further validation in larger series.