Early hepatic regeneration index and completeness of regeneration at 6 months after partial hepatectomy

The liver is known to regenerate following partial hepatectomy (PH), but little is known about the timing and completeness of regeneration relative to the resected volume. This study examined whether liver volume regeneration following PH and its completeness 6 months after surgery is related to the resected volume.

A consecutive series of patients undergoing PH were included. All patients underwent preoperative computed tomography (CT) before and 7 days after surgery. Additional scans were performed 6 months after operation. Preoperative total liver volume (TLV), resected volume, future liver remnant (FLR) and liver remnant (LR) volumes were measured on CT images by freehand drawing of regions of interest in the portal venous phase on 2-mm thick slices. Regeneration indices were calculated at 7 days (RI(early)) and 6 months (RI(total)) using the formula 100 × (LR volume-FLR volume)/FLR volume. Patients were classified into five groups based on resected volume as a percentage of TLV: 0-19, 20-39, 40-59, 60-69 and at least 70 per cent in groups 1-5 respectively.

Ninety-one patients were enrolled. RI(early) varied from 11 to 66 per cent in groups 1-5 (P < 0·001). RI(early) did not increase linearly with increasing resection volume and a plateau was seen from group 3 and above. In contrast, RI(total) was related linearly to resected volume; values ranged from 21 to 233 per cent in groups 1-5 (P < 0·001). At 7 days, LR volume represented 97, 87, 70, 58 and 41 per cent of TLV in groups 1-5. At 6 months, respective values were 102, 99, 87, 82 and 91 per cent.

Early postoperative liver volume regeneration was not related linearly to resected volume. At 6 months after surgery, RI was related linearly to resected volume, but LRs had not yet regenerated to preoperative TLV.