Diethylnitrosamine-induced Hepatic Carcinoma In Rats: MRI And Pathological Studies

Objective: To investigate the MRI features and histologic findings of induced hepatic carcinoma in rats, so as to further evaluate the therapeutic effect of angiogenesis inhibitor on hepatic carcinoma.Materials and Methods: Hepatic carcinogenesis was induced in 60 SD rats using oral diethylnitrosamine(DENA) for 14 weeks. During the 18^th and 22nd week after inducement, the rats were studied by MRI (with T1, T2 and proton-weighted MR imaging) and postmortem histologic examination (with macro- and microscopy by HE dyeing).The sizes of focuses were divided into four grades: less than 2mm, 2⁵mm, 5¹0mm and over 10mm. The numbers, distribution and signal intensity(SI) of tumors were assessed; the differences between detecting rates were tested by statistical software—SPSS 11.5; and the correlation between MRI features and histologic findings were evaluated.Results: Hepatomas developed in all studied rats. Focuses in four of the rats were invisible in MRI. Forty rats had more than three focuses each, the others had either one or two. The focuses detected in MRI were totally 214, 147 of which had uniform SI, and 110 had lower Tl and higher T2 SI. Thedetecting rates of Tl, T2, and proton-weighted images were 61%, 83% and 80%, respectively; 29%, 73% and 66% for focuses less than 2mm; and 73 %, 84% and 81% for focuses between 2mm and 5mm, respectively. Almost all focuses over 5 mm were detected with T1W, T2W and proton-weighted. There is statistical difference between the total detecting rates of all focuses and focuses less than 2mm with Tl WI and T2WI (PO.05), but no difference for focuses more than 2mm, neither between proton-weighted images and T2WI. Two hundreds and fifty-seven focuses were detected in specimen, which were divided into grade I (90), II (76),III(65) and IV(26). There was correlation between sizes of focuses and pathological grades(Spearman rank correlation coefficient is 0.662, PO.05), also between sizes and the uniform extent of SI(Spearman rank correlation coefficient is 0.646, P<0.05).Conclusion: The diethylnitrosamine model for hepatic carcinoma in rats provides a more representative range of tumors for experimental evaluation. In detecting focuses, T2WI is more sensitive than proton-WI and T1WI ,which has the least sensitivity among them. There is correlation between sizes of focuses and pathological grades, as well as between sizes and the SI. MRI features can reflect the pathological findings of hepatic carcinoma in rats. MRI is one of the most efficient examinations for detecting hepatic carcinoma, and can be used to evaluate the therapeutic effect on it.