| Objective: Conventional magnetic resonance imaging features of patients with hepatic alveolar echinococcosis and the secondary hepatic alveolar echinococcosis(HAE)animal model,and the imaging features of quantitative magnetic resonance imaging with T1 mapping and intravoxel incoherent motion diffusion weighted imaging were analyzed,and compared with pathology,to investigate the dynamic evolution of magnetic resonance imaging and its relationship with pathological changes in different periods of HAE,and to evaluate the value of functional magnetic resonance imaging and quantitative magnetic resonance imaging in the evaluation of the activity of the disease.Methods: 54 cases of HAE diagnosed by surgery or comprehensive imaging diagnosis in our hospital from January 2011 to May 2016 were collected,to analyze the characteristics of HAE conventional magnetic resonance imaging,and to compare the correlation between the Kodama classification,the maximum diameter of the lesion,the vesicle around the lesion,the high signal band around the lesion on DWI and the clinical stage of PNM.The IVIM DWI and T1 mapping sequence examination were performed on 21 patients with HAE in the same period.The focus area,cystic area,peripheral area,and the background of the liver were selected as the region of interest to measure the IVIM parameters and T1 values.At the same time,the peripheral microvessel density(MVD)was measured in 18 cases of resected lesions to compare the IVIM parameters and T1 values of different regions,and to analyze the correlation between IVIM parameters value,T1 value and MVD.On the other hand,the intrahepatic injection of echinococcus multilocularis suspension under open vision was used to prepare the animal model of secondary hepatic alveolar echinococcosis in rats.The rats were screened by ultrasound at the ninth week after inoculation.Rats were scanned from different experimental groups for MRI scanning at the 10 th,18th,and 32 th week after inoculation,including conventional MRI sequence,IVIM-DWI and T1 mapping sequence examination.The focus area,peripheral area,and the background of the liver were selected as the region of interest to measure the IVIM parameters and T1 values.At the end of the study,10 rats in each group were randomly sacrificed and the experimental specimens were taken for routine HE staining,Masson staining and MVD counting.Results: According to the Kodama classification,the lesions of HAE were divided into 5types: Kodama type 1(2.63%,2/76),Kodama type 2(18.42%,14/76),Kodama type 3(51.32%,39/76),Kodama type 4(26.32%,20/76),Kodama type 5(1.32%,1/76).In this study,22.37%(17/76)lesions were at P1 stage.7.89%(6/76)lesions were at P2 stage.60.53%(46/76)lesions were at P3 stage.9.21%(7/76)lesions were at P4 stage.44.74%(34/76)lesions were at N1 stage.18.42%(14/76)lesions were at M1 stage.30.26%(23/76)HAE lesions were surrounded by vesicles.The high signal bands whose size varies in width around the lesion were seen in 47.37%(36/76)lesions in the DWI sequence.According to the statistical analysis,there was no correlation between the Kodama typing and the maximum diameter of the lesions(r=0.243,P=0.697).P staging was positively correlated with the maximum diameter of the lesions(r=0.516,P<0.000).There was also a positive correlation between N staging and the maximum diameter of the lesions(r=0.754,P<0.000).There was no correlation between M staging and the maximum diameter of the lesions(r=0.214,P=0.063).There was no correlation between HAE peripheral vesicles and the clinical stage of PNM.On DWI sequence,the surrounding high signals of HAE were positively correlated with and P staging(r=0.601,P=0.045)and M staging(r=0.314,P=0.033),but not correlated with N staging(r=0.325,P=0.093).After the IVIM DWI sequence was carried out for dynamic scanning and image post-processing on rat HAE models,it was found that there were significant differences in D value and f value in different stages of HAE lesion area,peripheral lesion area and background liver.There was no significant difference in D* value between the lesion area and the surrounding area,while the D* of the background liver area was larger than that of the lesion and the surrounding area.The f value of surrounding area in the occurrence and development of HAE was statistically significant at each stage and the f value was positively correlated with microvessel density counting.The D value was slightly different at different time points,and the early D value was slightly higher than that of the late stage.There was no statistical difference in D* value at each time points.After the IVIM DWI sequence was carried out on HAE patients,it was found that there was no significant difference in D values in the background liverand the surrounding area,but there was a statistical difference in the other regions.There was no significant difference in f values in the solid and cystic areas,but there was a statistical difference in the other regions.There was no significant difference in D*values in the other regions except the cystic area and the surrounding area.After the T1 mapping sequence was carried out for dynamic scanning and image post-processing on rat HAE models,it was found that there was a statistical difference between the T1 values of each region,but there was no significant difference in T1 value at different time points.After the T1 mapping sequence was carried out on HAE patients,it was found that there was a statistical difference in the T1 values of other regions except for the solid area and the surrounding area.Conclusion: 1)The state of blood flow around the HAE lesions was different from that of the internal lesions and background liver.The f value derived from the IVIM DWI sequence can well reflect the state of blood flow in the peripheral area of the lesion.2)The dispersion states of each region in HAE were different.With the extension of time,the D value in the peripheral area of the lesion may reflect the state of local fibrosis.3)The IVIM DWI sequence is better than the quantitative MRI sequence T1 mapping in reflecting the pathological changes of HAE lesions. |
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