Functional assessment of liver regeneration after major hepatectomy.

Background: Liver regeneration is crucial to restore the functional liver mass after liver resection. The aim of this study was to evaluate the early postoperative changes in remnant liver function, volume and liver stiffness after major liver resection and their correlation with postoperative outcomes. Methods: Patients undergoing major liver resection (≥3 segments) between February and November 2018 underwent both functional assessment using technetium-99m mebrofenin hepatobiliary scintigraphy (HBS) and CT-volumetry of the (future) remnant liver on preoperative day 1, the 5th postoperative day, and 4-6 weeks after resection. At the same time points, patients underwent transient elastography (TE) for the assessment of liver stiffness. Severe postoperative complications (Clavien-Dindo ≥ 3A) and mortality were correlated with the functional and volumetric increases of the remnant liver. Liver failure was graded according to the International Study Group of Liver Surgery (ISGLS) criteria. Results: A total of 18 patients were included of whom 10 (56%) had severe complications and one patient (5%) developed liver failure. Function and volume of the remnant liver had increased by the 5th postoperative day from 6.9 (5.4-10.9) to 9.6 (6.7-13.8) %/min/m2, P=0.004 and from 795.5 (538.3-1,037.5) to 1,080.0 (854.0-1,283.3) mL, P<0.001, respectively. After 4-6 weeks, remnant liver volume had further increased [from 1,080.0 (854.0-1,283.3) to 1,222.0 (1,016.0-1,380.5) mL, P=0.035], however, liver function did not show any significant, further increase [from 9.6 (6.7-13.8) to 10.9 (8.8-13.6) %/min/m2, P=0.177]. Liver elasticity of the future remnant liver (FRL) increased [from 10.8 (5.7-18.7) to 17.5 (12.4-22.6) kPa, P=0.018] and gradually recovered after 4-6 weeks to a median of 10.9 (5.7-18.8) kPa (T3 vs. T4, P=0.079). Patients who had severe postoperative complications did not show a significant increase in liver function on the 5th postoperative day (P=0.203), despite increase of volume (P<0.01). Conclusions: Functional regeneration of the remnant liver predominantly occurs during the first 5 days after resection. In case of severe complications, functional regeneration is delayed, in contrast to volume increase.