Abstract：Objective: To characterize liver perfusion in Wistar rats with experimental liver fibrosis by dynamic contrast-enhanced MRI and to correlate it with the severity of liver fibrosis. To evaluate the diagnostic efficacy of perfusion MR imaging for liver fibrosis. Methods: Mixed solution of CCl4 and olive oil was hypodermically injected to fifty Wistar rats in the experimental group. Ten healthy rats served as control. MR perfusion study with dynamic contrast-enhanced MRI was carried out on the rats under anesthesia. The rats were divided into S0~S4 stages according to the histological results of liver. Time to peak(TP), wash-in rate and wash-out rate was compared between the groups using variance analysis, and the relationship between each perfusion parameters and severity of liver fibrosis were made by correlative analysis. Results: Forty-eight rats underwent MR perfusion study, including ten rats in the normal group. Histological results S0（n=13）, S1（n=5）, S2（n=9）, S3（n=13）, S4（n=8）. On signal intensity time curve(SI-T) derived from MR perfusion weighted imaging(PWI), TP of portal vein and liver in fibrotic group[mean, (26.29±3.52)s and (41.92±5.76)s] increased progressively compared with control group[mean, (15.03±1.05)s and (25.93±1.70)s]. S2~S4 stage can be distinguished from S0 stage(P<0.05, <0.001, <0.001, respectively). Wash-in rate and wash-out rate of portal vein and liver in fibrotic group[mean, PV(292.61±40.02)1/s and (139.73±13.22)1/s, liver (76.70±9.55)1/s and (97.56±15.73)1/s] decreased progressively compared with control group[mean, PV(420.46±27.26)1/s and (193.50±16.76)1/s, liver(140.10±16.73)1/s and (121.00±15.16)1/s]. S3 and S4 stage can be distinguished from S0~S2 stage(P<0.05). TP value of the SI-T curve was significantly positive correlated to the severity of liver fibrosis(P<0.01). The wash-in rate and wash-out rate value were significantly negative correlated to the severity of liver fibrosis, respectively(P<0.01). Conclusion: MR-PWI has a potential in diagnosing and grading experimental liver fibrosis. PWI is an effective method to detect moderate and severe fibrosis(S2~S4 stage).
2009, Vol. 20 
