| Objective:1. To eatablish the animals models carrying inflammatory pseudotumor of the liver(IPL) in rabbits with Freund's complete adjuvant serving for MRI study purpose. And to analyze its MRI manifestations before and after enhanced by Gd-DTPA and SPIO. Then correlating the model' pathologic finding.2. To investigate MRI features of the inflammatory pseudo tumor of the liver in human, and correlated with the features to the pathologic findings, analyze it's differential diagnosisMaterials and Methods:12 rabbits were injected with Freund's complete adjuvant into left lobe of the liver at the dose of 2.0 ml per rabbit (n=12). All animals underwent MRI scan 14 days after the injection. MRI scans involved plain scan, Gd-DTPA enhanced FL2D sequences dynamic scan and SE-T1 sequence delay scan, SPIO enhanced TSE-T2 sequence scan and SE-T1 sequence. Then the lesions were harvested for further pathological examinations.The MRI findings of 18 case of IPL were retrospectively reviewed, and correlated with pathologic findings. The MRI scans involved both plain and Gd-DTPA enhanced MRI scanning. All the cases were proved IPL patho-histologily with aspiration needle biopsy specimens guided by CT or B-ultrasounds or surgery. The IPL's MRI features were summarized, and it's differential diagnosis were analysised.Results:1. There were 10 IPL detected in 10 rabbits of all 12 rabbits (incidence rate was 83.3%). With the tumor size of 2.5 +1.0 cm, the lesions were hypo-iso-intensity or slightly hyperintensity on T1 weighted images and hyperintensity on T2 weighted. When enhanced by Gd-DTPA, the lesions showed slowly reinforcement and has the best conspicuous in the delayed phase T1-weighted SE sequence imaging. While enhanced by SPIO, the lesions did not change much but intensity of normal hepatic parenchyma reduced sharply in T2WI. The contrast of intensity between lesion and liver rose apparently. Histologically, there were necrotic areas within the nodulesassociated with fibrous proliferation and inflammatory cells infiltrated.2. There were 20 lesions in 18 cases being detected, most of them located in the right lobes of liver, the lesions were round or round-like, triangle or abnormal in shape All lesions showed slightly-low-intensity signal on plain scanning T1WI and iso-intensity or slightly-high-intensity signal on T2WI. Dynamic enhanced MR imaging revealed that most lesion were not enhanced markedly immediately after gadolinium administration, during portal-venous phase and delay phase scanning, the lesions show no-reinforcement, edge enhanced, slightly to intermediate enhanced, round-ring reinforcement and nodes reinforcements. It also reviewed there are correlation between MRI finding and it's pathologic features and stages of the IPL.Conclusions:1.The model bearing IPL in rabbits induced by Freund's complete adjuvant has the advantage of high incidence rate, short latent period, easy duplication, it also have the pathologic feature of necrotic constitution, fibrous proliferation and inflammatory cells infiltrated. The model could be served as ideal experimental animal model for further study of IPL's etiopathology and imaging features.2.Gd-DPTA could enhance signal to noise ratio of IPL in rabbit, improved it's conspicuity. IPL were lesions of hypovascularity, it's signal increased slowly, it's details manifested best in the delayed phase imaging, the envelope show as bandlike reinforcement outside the lesions.3.SPIO particle can't be absorbed by IPL. But it reduced normal liver parenchyma significantly, thus increased signal ratio of lesion-to-liver. IPL didn't possess reticuloendothelial system, when enhanced by SPIO, it's signal changed little in T2WI.4. The MRI features of the IPL in human were: (1) Most IPL located in the right lobes of the liver, with the shape of roundness, round-like, triangle, poly-nodes confluence or abnormity; (2) All lesions showed low or slightly-low-intensity signal on plain T1WI scanning and high or slightly-high-intensity iso-intensity or signal on T2WI, the...
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