Assessment of liver fibrosis using T1 mapping on Gd-EOB-DTPA-enhanced magnetic resonance.

Background: Few studies have investigated the value of Gd-EOB-DTPA-enhanced T1 mapping in exact fibrosis staging, especially its correlation with hepatic molecular transporters.

Aims: To investigate the diagnostic value of Gd-EOB-DTPA-enhanced T1 mapping in staging liver fibrosis and its relationship with hepatic molecular transporters.

Methods: Thirty rats were divided into the carbon tetrachloride-induced fibrosis groups and a control group. T1-mapping was performed before and 20min after administration of Gd-EOB-DTPA. The T1 relaxation time and reduction rate (Δ%) were calculated, and their correlations with the degree of fibrosis, necroinflammatory activity, iron load and hepatic molecular transporters were assessed and compared.

Results: Hepatobiliary phase T1 relaxation time (HBP) and Δ% were different between each adjacent fibrosis subgroups(P=0.000-0.042). Very strong correlations existed between fibrosis and both HBP and Δ% (r=0.960/-0.952), and multivariate analyses revealed that fibrosis was the only factor independently predicted by HBP (P=0.000) and Δ% (P=0.001), comparing to necroinflammatory activity and iron load. The expression of the organic anion transporting polypeptide1a1 (Oatp1a1) was significantly correlated with HBP and Δ% at both mRNA (r=-0.741/0.697) and protein (r=-0.577/0.602) levels. Weaker correlations were found for multidrug resistance associated protein2 (Mrp2). Generally, both transporters showed decreasing levels with increasing degrees of fibrosis.

Conclusion: Gd-EOB-DTPA-enhanced T1 mapping may provide a reliable diagnostic tool in staging liver fibrosis, and can be regarded as a useful imaging biomarker of hepatocyte transporter function.