Human liver regeneration after major hepatectomy. A study of liver volume by computed tomography. Regeneration of the remnant liver after major hepatectomy in humans was studied by computed axial tomography (CT) in 12 noncirrhotic and five cirrhotic patients. Liver volumes were measured by abdominal CT 3 days, 10 days, 3 months, 6 months, 1 year, and 1.5 years after resection. Of the 17 patients, liver remnant volume was increased in 21.2% +/- 6.7% and 30.6% +/- 12.7% at 3 months and 6 months after resection, respectively. Noncirrhotic livers were 28.4% +/- 9.5% and 48.4% +/- 17.8% larger at 3 and 6 months. For cirrhotic livers, the increase was 8.5% +/- 3.6% and 12.9% +/- 4.5%. In five patients with right hepatectomy (65% resection), the liver remnant volumes were increased 38.4% +/- 11.7%, 48.0% +/- 16.2% and 95.1% +/- 4.5% at 3 months, 6 months, and 1 year after resection, respectively. In seven patients with right partial hepatectomy (30% to 35% resection), the percentages were 7.4% +/- 3.2%, 21.8% +/- 8.4%, and 63.9% +/- 18.3% and in five patients with left lateral segmentectomy (15% resection), they were 15.6% +/- 8.2%, 27.8% +/- 12.2%, and 33.0% +/- 14.5% 3 months, 6 months, and 1 year after resections, respectively. Noncirrhotic livers showed better regeneration than cirrhotic livers. Complete regeneration took about 1 year. The noncirrhotic liver that underwent right lobectomy also needed 1 year to double its postresection volume. 