| Objective1.To observe the CT,MRI changes in tumors and surrounding parenchyma of hepatictumors after three-dimensional conformal radiation therapy.2.To analyze the relationship between the CT, MRI findings and pathology.The first part:animal experimental studyMaterials and Methods1. VX2 carcinoma cells were implanted into the liver of 17 New Zealand white rabbits, which were underwent CT and MRI scan after two weeks. Two rabbits were killed, 15 rabbits were randomly divided into 3 groups(5 rabbits per group):control(A) , single-dose radiation 10Gy(B) ,30Gy(C)..2. After 6 weeks, CT and MRI were performed on 15 rabbits again. To measure the tumor mean diameter (TMD).3. The rabbits were killed after scan. To choice the identical tissue area with region of interest on CT/MRI, It was stained with HE and immunohistochemistry.Results:1. The rumors increased rapidly in group A. The tumors were shown to be hypodensity on noncontrast CT, hypointensity on Tl WI and slightly hyperintensity on T2WI by MRI scan,with peripheral enhancement of tumors in 4 weeks after radiation.There was significant difference between group B,C and group A in TMD. The tumors density was shown to be lower than pretreatment. Postcontrast images showed enhanced in 7/10 rabbits.2. 3/10 rabbits appeared limited hepatic injury, which was observed as hypodensity areas on noncontrast CT. 7/10 rabbit's irradiation areas showed hypointensity on T1WI and slightly hyperintensity on T2WI.Postcontrast images showed hyper intensity .It was significant difference between CT and MRI in sensitivity of finding the hepatic injury.3. 55% cases were positive for VEGF expression in control group and 80% cases were positive in 3-DCRT group .There was relationship between VEGF level and MRIenhancement degree of tumors after 3DCRT. The second part -.clinical studyMaterials and Methods:1. 52 patients with primary hepatocarcinoma underwent radiotherapy DT: 35~65 Gy/7~30F /13~28d. Target volume isl0.52~918.20cm3(204.77?17.48cm3.2. Patients were divided into two groups, group I(early stage) (n=42), group II(late stage) (n=40) and were investigated to 3 weeks ~6 months and 6~48months after the end of irradiation, respectively.Results:1. TMD after radiotherapy was significant smaller than pretreatmentThe tumors showed hypodensity on CT scan and hypointense on Tl WI and hyperintense on T2WI.2. 67.7%patients showed the appearance of limited hepatic injury In the early stage, which as hypodense areas on non contrast CT corresponding to the irradiation area after the end of radiation.The size of hypodensity irradiated areas decreased in late stage. It was found that the density in early stage was lower than that of in the late stage in contrast enhanced dynamic scan..78.6% irradiation areas showed hypointensity on Tl weighted and slightly high intensity on T2weighted in early stage.Postcontrast images showed hyperintensity on arterial phase(10/ll),and contrast enhancement tended to be more prominent and prolonged in portal phase. One case (1/11) showed no enhancement. The irradiated areas decreased and showed hypointensity or isointensity on T1WI and slightly hyperintensity on T2WI. Postcontrast images showed obvious hyperintensity in all sequence..MRI were performed both in early stage and late stage in 9case, it was found that the signal intensity was significant difference between early and late stage.3. Recurrent carcinoma and the irradiated area showed similar image: hypointense on Tl WI and hyperintense on T2WI.In the dynamic enhancement study, recurrent tumor showed early enhancement in arterial phase, followed by a rapid washout. However, the irradiated voulme of liver parenchyma showed hypointensity on arterial phase .and contrast enhancement tended to be more prominent and prolonged in portal phase.5. The risk factors of radiation-induced limited liver injury correlated to the total dose, fractional dose ,the target volume and liver cirrhosis. It couldn't find significant...
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