An Experimental Study Of Biochemical, CT Images And Pathologic Changes On Radiation-induced Hepatic Injury

Objective1. To explore the hepatic function changes, coagulation function changes and hepatic fibrosis changes in different radiotherapy dose groups.2. To observe the appearance of multiphase contrast-enhanced CT both before and after radiotherapy; to compare the CT value of the left (or right) semi-liver before radiotherapy with the CT value of the same semi-liver after radiotherapy in different CT scan phase.3. To observe the characteristics of pathologic changes after radiotherapy and to review the appearance of liver fibrosis.Methods1. Grouping the experimental animals——Twenty New Zealand White Rabbits were divided randomly and averagely into 4 groups which were group A, B, C and D. The group A was control group of normal rabbits, the group B,C and D were separately treated with 10Gy,15Gy and 20Gy.2. Semi-liver radiotherapy——①Anesthesia procedure SumianxinII(SMX) and Ketamine were mixed in the ratio of 1:1. The rabbits were given the mixture intramuscular injection at the dose of 0.3ml/Kg. According the methods above-mentioned, we anesthesia the rabbits of B, C, D groups.â‘¡Position and fast The rabbit laid on its back, and was fast on the wood-made platform. Then the platform was located in the negative pressure vacuum mat.â‘¢Location We used CT scan to locate, and the scan range from diaphragmatic dome to margo interior hepatis. Then we transmitted the CT images to TPS work station.â‘£Planning We regarded the right side of the cholecyst as the right semi-liver which was the radiotherapy target. 55% isodose curve was as the reference curve.⑤The stereotactic radiothe- rapy with 2.5 collimating apparatus.3. Chemical examination——All experimental rabbits were given the chemical examination including hepatic function, coagulation function and hepatic fibrosis assembly. The examinations were performed before radiotherapy and 48 hours, 1st week, 2nd week, 1st month, 2nd month, 3rd month after radiotherapy. The rabbits should be abrosia for at least 8 hours before haemospasia, then were fasten in a special box. The vein on the edge of rabbit ear was besmeared with xylene, then took suction the blood example 2ml from the well engorge vein.4. CT scan——The rabbits of B, C, D groups were given the plain CT scan and multiphase contrast-enhanced CT scan both before radiotherapy and 3 months after radiotherapy. The multiphase contrast-enhanced CT scan: contrast medium (Ioversol 350 attenuated 300 with 8.3ml 0.9% NS ) at a speed of 0.5ml/s, injected 5ml. The artery phase was 15s, portal vein phase was 41.5s and prolonged phase was 103s. According to the above-mentioned methods, we got the images of plain CT scan and multiphase contrast-enhanced CT scan.5. Observation of the liver tissues by light microscope——After the experimental rabbits were killed, we cut 3 pieces of liver tissues which size was about 1cm³. We cut the tissues from special areas: High dose area (the center of radiation target), low dose area (the edge of radiation target), non-radiation area (lateral lobes of left semi-liver). The liver tissues were infiltrated in formalin thoroughly, then embed in paraffin. The section was 5um in series and then stained with HE and Masson, after that, observation by light microscope.6. Statistics——Utilized the statistical software of SPSS 13.0 for handling all the data of this experiment. The CT values of left (or right) semi-liver in different phases and all of the chemical examination values were handled with repeated measurement data analysis of variance. The appearance of pathology was described in details and we built a form for analysis.Results1. Survival rate of the experimental rabbits——A, B and C groups had no rabbit died, the survival rate was 100%. Group D had 3 rabbits died, and the survival rate was 40%. So the group D did not take part in statistical analysis. The three rabbits of group D (20Gy) were died 5-10 days after radiation. They had the same symptoms which were diarrhea, loss of appetite, listlessness and debilitation.2. Results of chemical examination——①Hypohepatia We monitored all of the chemical values for 3 months after radiotherapy, and found AST, TBIL, DBIL, TP, ALB risen (P_AST<0.05,P_TBIL<0.05,P_DBIL<0.05,P_TP<0.05,P_ALB<0.05);GGT fluctuated in 3 months, decreased in 24 hours after radiation and risen again after 2 months( PGGT<0.05); ALP decreased obviously in 24 hours after radiation, and kept on decreasing a half until the 3rd months after radiation(PALP<0.05). ALT and PA had no changes in this 3 months(PAlT>0.05,P_PA>0.05)。②Coagulation function——PT,PTINR had no changes(PPT>0.05,PPTINR>0.05); PT%,FbgC,TT of group B and C all changed in 3 months(P_PT%<0.05,P_FbgC<0.05,P_TT<0.05). FbgC,TT began to rise on the 1st day after radiation, then got to the highest level after 1 week, and decreased to the normal level at the 2nd week. PT% fluctuated all the time in this 3 months.â‘¢Hepatic fibrosis assembly——Hepatic fibrosis values had no apparent changes in 3 months.(P_LN>0.05,P_PcIII>0.05,P_IV.C>0.05).3. Results of CT scan——①Appearance of CT scan The appearance of CT scan before radiotherapy were uniformity densities of liver when give the experimental rabbits plain CT scan, slight enhancement in artery phase, apparent enhancement in portal vein phase, weak enhancement in prolonged phase. The groups of B, C and D (the total number of the rabbits was 12) were given the CT scan examination 3rd month after radiation. The liver'size and appearance had no changes, and the liver's densities was uniformity. The appearance of multiphase contrast-enhanced CT scan was no enhancement in artery phase, weak enhancement of whole liver in portal vein phase and hepatic vein blur, little enhancement in prolonged phase. Either plain CT scan or multiphase contrast-enhanced CT scan could not get the liver's densities changed which was united with isodose curve.4. Results of pathology——①Gross appearance The liver of group A was brunneus, it's surface was smooth, and the texture was soft and fragile. However the surface and cut surface of group B, C and D's livers was gray-yellow, and the center of diaphragmatic surface was especial apparent. The edge of the liver was gray-red. The changes above-mentioned were apparent when the rabbits were given high radiation dose. All of the hepatic lobes had no difference from gross appearance.â‘¡Light microscope The livers of group B, C and D which were 3 after radiotherapy months could be seen the center veins and blood sinus congestion under the light microscope. Also we could see venous occlusive disease, around the bile duct was lots of inflammatory cells, collagen fibers in the portal areas were increased. The changes above-mentioned aggravated because of the radiotherapy dose increased. The appearance of radiation induced liver disease in same liver was different, the high dose area more serious than low dose area and the low dose area more serious than non-radiation area. The change tendency was not apparent like the appearance changes because of the radiation dose changes.Conclusion1. When the r-knife radiate half-liver and the dose increase to 20Gy, the mortality increases apparently, about 60%. The reasons of dead are radiation induced enteritis and radiation induced liver disease.2. Liver radiotherapy can lead to hypohepatia. And the main chemical values changes were that aminopherase and bilirubin risen from the 1st month after radiation, and alkali- phosphatase decreased in 3 months.3. Liver radiotherapy can lead to coagulation function change. FbgC,TT rise in a week after radiation, and then decreased to the normal level on the 2nd week. FbgC,TT is sensitive about the early radiation induced liver disease.4. The hepatic fibrosis assembly values have no apparent changes after radiotherapy compared with before radiotherapy. However we found collagen fibers in the liver though light microscope. So the hepatic fibrosis assembly is not very helpful for diagnosis of RILD.5. If a healthy rabbit's liver has radiation induced liver disease, the appearance of CT scan is I type change: we can not see the apparent enhancement in artery phase, in portal vein phase and in prolonged phase. The area of radiation induced liver disease has the same density with the area of normal liver.6. Because of the radiation dose increased, the venous occlusive disease, hepatic fibrosis and bile duct injury more serious. The high dose area and low dose area are serious than non-radiation area in the same liver after radiotherapy.