Volumetric graft changes after liver transplantation: evidence of adaptation to recipient body size

Abstract

Introduction: It is believed that whole liver grafts adjust their size to fit the body size of the recipient after transplantation, despite lack of evidence. The aim of this study was to test this hypothesis. Methods: This was a retrospective cohort study of 113 liver transplantations performed at Karolinska University Hospital. The cohort was divided based on graft volume-to-standard liver volume ratio (GV/SLV) into quartiles of small, mid and large grafts. Serial volumetric assessment was performed on the day of transplantation and at post-transplant check-ups early (<2 months) and late (9-13 months) after transplantation using computed tomography (CT) volumetry. Change in GV/SLV-ratio over time was analyzed with ANOVA repeated measures. A multiple regression model was used to investigate the influence of intraoperative blood flow, recipient body size, age and relative sickness on graft volume changes. Results: Between the three timepoints, mean GV/SLV-ratio adapted to: 0.55 -0.94 - 1.00 in small grafts (n=29, p<0.001); 0.87 - 1.18 - 1.13 in mid grafts (n=56, p<0.001); 1.11 - 1.51 - 1.18 in large grafts (n=28, p<0.001). Regression analysis showed a positive correlation between post-transplant graft growth and portal flow (β=1.18, p=0.005), arterial flow (β=0.17, p=0.001) and recipient body surface area (β=59.85, p<0.001). A negative correlation was observed for graft weight-to-recipient weight ratio (GRWR) (β=-33.12, p<0.001). Conclusions: Grafts with initial GV/SLV-ratio<0.6 adapt towards the ideal volume for recipient body size one year after transplantation. The disparity between graft size relative to recipient body size, and the portal and arterial perfusion, influence volumetric graft changes.