Correlative Study Of MRI Manifestations With Pathology And Proliferative Activity Of Rabbit VX2 Hepatic Carcinoma

Purpose:To investigate the pathologic bases of MRI manifestations and the relationship between MRI manifestations and proliferative activity of rabbit VX2 hepatic carcinoma.Materials and Methods:20 Rabbit VX2 Hepatic Carcinoma Models with 32 foci were successfully set up by implanting method,and MR examinations were performed with a Horizon 1.5T MR system at 2-4 weeks after implantation. T2-weighted fast SE images and TI-weighted SE images were acquired in the axial plane in all the foci. Contrast-enhanced MRI and delayed contrast-enhanced MRI were administrated immediately and at 10 minutes after a intravenous bolus injection of Gd-DTPA in 15 foci. The largest transverse section specimens of all the tumors were obtained after MR scan and made into paraffin blocks,from which 2 micron sections were prepared to perform HE staining and PCNA immunohistochemical staining respectively. The HE stained sections were applied in the contrast study of MRI manifestations with pathology,and the PCNA immunohistochemical stained sections were applied in determining the proliferative activities of the tumors.Results:All the 32 tumors were detectable on both T1WI and T2WI. The size of the tumors ranged from 0.5 to 3.5cm (mean,1.8 cm) in diameter. The results of the correlative study of MRI characteristics with pathology and proliferative activity of rabbit VX2 hepatic cacinoma were as follows:1. Corrlation between MRI signal intensity and pathology of the main bodies of the rumors. All the main bodies of the 32 tumors appeared asslightly hypointensity on TIWI and slightly hyperintense on T2WI. 6 of the 32 tumors were performed electronic microscopic examination,and it was discovered that there were a lot of dilated mitochondrias and endoplasmic reticulums in the cytoplasm under the electronic microscope.2. Pathological bases of the signal intensity features within the tumors on T2WI. Characteristic signal changes were found in 26 of the 32 tumors on T2WI. 5 of the 26 rumors presented "nodule in nodule" sign,which demonstrated that there was a nodular hypointense area in the center of the slightly hyperintense nodular tumors. The nodular hypointense areas were also shown as "more hypointense areas" in the slightly hypointense nodular tumors on TIWI,and were confirmed pathologically as coagulation necrosis. 7 tumors presented " target " sign on T2WI,6 of which demonstrated three-layer structures:the inner part appeared as patchy hyperintensity,the outer part appeared as thin annular slight hyperintensity and the median part appeared as annular slight hyperintensity (slightly higher than the intensity of the outer part). The other one demonstrated four-layer structures,there was another slightly hyperintense rim around the outer part,the intensity of which was as same as that of the median part. Both of the outer and median parts were shown as slight hypointensity on TIWI,were confirmed pathologically as tumor tissue and slightly-moderately disintegrated necrostic tissue respectively. The inner parts was shown as "more hypointense areas" on TIWI,and were confirmed pathologically as severely disintegrated necrostic tissue. The outermost rim of the tumor presenting four layer structures was confirmed pathologically as significantly dialated sinusoidlike vessels around the tumor. 14 rumors prsented " dot and color " sign on T2WI,which demonstrated that there were several abnomal signals with different intensity,size and shape in the slight hyperintensity of the nodular tumors. 17 distinct abnormal signals in the largest transverse T2WI of the 14 tumors were chosen to study the relationship between the signal intensity and pathology,6 of which appeared as patchy hyperintensity,8 appeared as patchy slighthyperintensity,and 3 appeared as lineal isointensity. The 6 hyperintense abnomal signals were all shown as "more hypointense areas" on T1WI,and were confirmed pathologically as severely disintegrated necrostic tissue. The 8 slight hyperintense abnomal signals were all confirmed pathologically as moderately dis...