A novel formula for graft weight estimation from preoperative computed tomography volumetric measurement in living donor liver transplantation

Abstract

Background: Computed tomography (CT) is the current gold standard for preoperative assessment of graft volume in the context of living donor liver transplantation (LDLT) despite the commonly noted mismatch between CT estimated graft volume (CT-GV) and actual graft weight (AGW). Aim: to find a formula that correlates preoperative virtual CT graft volume with AGW measured on the back table. Methods: CT volumetric data as well as AGW of 125 consecutive living liver donors in the period between 2010 and 2016 were reviewed. Correlation between CT-GV and AGW was done. Formula for line of best fit was obtained by plotting CT-GV against AGW for right and left lobes using linear regression analysis. Results: One hundred and nineteen living donors had complete data allowing downstream analysis. Donors were mostly males (59.7%) with mean age of 28.4±6.7 years. Ninety-seven of them (81.5%) donated right lobe while 22 (18.5%) left lobe grafts. Mean CT-GV was 870.0±142.9 ml for right lobe grafts and 335.5±112.1 ml for left lobe grafts. Mean AGW was 851.7±162.9 g for right lobe grafts and 296.2±74.5 g for left lobe grafts. The following formulae were derived to calculate AGW (g): [0.92xCT-GV (ml)+51.48; R 2 =0.651, P<0.0001] and [0.53xCT-GV (ml)+120; R 2 =0.625, P<0.0001)] for the right and left lobe grafts respectively. Conclusion: We postulate reliable formulae to convert virtual CT-GV into AGW, to accurately correct the discrepancy between preoperative CT-GV and AGW in the setting of LDLT.