Multi-parametric magnetic resonance imaging of liver regeneration in a standardized partial hepatectomy rat model

BACKGROUND: We aimed to evaluate the correlation between the pathological changes and multi-parameter MRI characteristics of liver regeneration (LR) in a standard partial hepatectomy (PH) rat model. METHODS: Seventy Sprague–Dawley rats were randomly divided into two groups: MR scan group (n = 14) and pathologic analysis (PA) group (n = 56). All 14 rats in the MR group underwent liver T1 mapping, T2 mapping, and diffusion kurtosis imaging before and the 1st, 2nd, 3rd, 5th, 7th, 14th, and 21st day after 70% hepatectomy. Seven rats in the PA group were euthanized at each time point to determine Ki-67 indices, hepatocyte size (HTS), steatosis grade, and inflammation score. RESULTS: Liver T1 and T2 values increased to maximum on day 2 (P < 0.001 vs. baseline), D and K values decreased to minimum on day 3 and 2, respectively (P < 0.001 vs. baseline), then all parameters returned to baseline gradually. Hepatocyte Ki-67, hepatocyte size, steatosis grade, and inflammation score initially increased after surgery (P < 0.05 vs. baseline), followed by a gradual decline over time. Both T2 and K values correlated well with Ki-67 indices (r = 0.765 and − 0.807, respectively; both P < 0.001), inflammation (r = 0.809 and − 0.724, respectively; both P < 0.001), steatosis grade (r = 0.814 and − 0.725, respectively; both P < 0.001), and HTS (r = 0.830 and − 0.615, respectively; both P < 0.001). CONCLUSIONS: PH induced liver changes that can be observed on MRI. The MRI parameters correlate with the LR activity and allow monitoring of LR process.