Assessment of hepatic steatosis during rat liver regeneration after 70% partial hepatectomy using stereology and MRI-PDFF

Partial hepatectomy (PH) is the primary treatment for liver malignancies, leveraging the liver's regenerative capacity and metabolic potential. Transient hepatic steatosis is a common occurrence following PH. This study aimed to evaluate the utility of MRI-derived proton density fat fraction (MRI-PDFF) for assessing hepatic lipid content in the regenerating rat liver by correlating it with stereological lipid quantification, used as a histological reference standard. Rats were randomly assigned to 70%PH (n = 6) or no surgery (n = 6) and evaluated at postoperative day 1. Regeneration ratio was calculated, and lipid-specific biochemistry was measured. Hepatocyte proliferation and volume, as well as lipid volume per hepatocyte, were estimated using stereological analyses. Proton density fat fraction was quantified using MRI. Compared to controls, the PH group showed increased regeneration ratio, hepatocyte volume, and cell proliferation. Hepatic lipid accumulation was elevated, as demonstrated by both stereology and MRI. A strong positive correlation was observed between stereological lipid volume per hepatocyte and MRI-PDFF. High-density lipoprotein cholesterol levels were reduced in the PH group. This study demonstrates that stereological analysis and MRI-PDFF are complementary and reliable methods for quantifying hepatic steatosis in the regenerating rat liver. Their strong correlation supports MRI-PDFF for non-invasive, longitudinal monitoring.