| Objective: On the rabbit VX2 soft tissue tumor model: To observe the relationship between the CT perfusion parameters and the microvessel density (MVD) of the tumors; To determine whether it is possible to measure the effects of radiation on VX2 tumors, and to analysis the relation between the changes of the CT perfusion results and changes of the MVD after the radiation therapies. For the clinical CT examinations of the patients with astrocytoma tumors: To analysis the relationship between the CT perfusion parameters and the MVD of astrocytomas; To evaluate the value of CT perfusion on grading of astrocytomas; To observe the changes of the CT perfusion results of the residuary astrocytomas after radiation therapies; To discuss the value of the CT perfusion on follow-up examinations of cerebral tumors.Part One: The CT perfusion study of the rabbit VX2 tumor: before and after radiation therapyMethods and materials: 12 male New Zealand White rabbits which weighted 1.8kg ~ 2 .4kg were used in this experiment. They were implanted with the VX2 soft tumor in right thighs 2 rabbits and bilateral thighs in 10 rabbits. 2 weeks later, except the accidental death of 2 bilateral implanted rabbits , The VX2 tumors were formed in bilateral thighs 8 rabbits and in right thigh in 2 rabbits in size of 1.5cm~5cm. Subsequently, the radiation therapies were performed on the right thighs of the 8 bilateral implanted rabbits, while the tumors on the left thighs were regard as the comparing group. 60Co was used for the radiation therapy with the doses of 1200Gy. The CT scans were performed again 7days~8days after the radiation therapies.CT examination: A GE multi-slice spiral CT scanner was used in the present study(Iightspeed Ultra). The CT scan series including: plain scan, enhanced dynamic scan and enhanced scan. The scan parameters of the dynamic scan : cine acquisition, 80kV, 120mA,512 matrix, 15cm FOV, 5mm slice thickness(4 slices per rotation), Is per 360 revolution, total scan time 45s, 180 images were acquired . The contrast agent (Ultravist 300)were injected through the ear vein with dosage of 1.5ml/kg at rate of 1.5ml/s using an injection pump.With the help of perfusion 2 software, the blood flow(BF), blood volume(BV),(mean transit time (MTT),and permeability surface(PS)mapping images were acquired.The rabbits were put to death after the second CT examinations, and the tumors of the rabbits were taken out for normal HE and immunohistochemistry staining, The SP method was used for the immunohistochemistry staining. The anti-CD34 monoclonal antibodies were used to mark the microvessels. The MVD of the tumors were calculated using Weidner technique.Results: In all the 18 VX2 tumor lesions, central necrosis were demonstrated in 7 lesions, metastasis lymph nodes were found around 5 lesions, and calcification were seen in 4 lesions. The parenchyma of the tumors enhanced obviously on the enhanced images. The contours of the tumors were well described on the BF,BV, and PS mapping images but for MTT mapping images. Quantitive study show that the mean values of BF.BV and PS were 85.20 ml/min/100g, 15.33 ml/lOOg, 34.71 ml/min/100g much higher than that of normal muscle tissues which were 46.90 ml/min/100g, 2.26 ml/100g, 9.48 ml/min/100g, respectfully , The average values of MTT of tumors were approximately equal to the muscle. ( 5.49s, 6.20s).The average values of BF, BV, PS of the tumors decreased after the radiation therapies, There was a significant difference from that before radiation therapy(P<0.05).For the comparing group there ware no obviously changes on the CT perfusion parameters in the same time. The MVD of the tumors of the radiation therapy group were smaller than that of the comparing group, and there was a significant difference(P<0.01). Either inradiotherapy group or in comparing group there were a linear correlation between the MVD and BF, PS, BV of the tumors.Part two: CT perfusion study of the histopathologic grade of astrocytoma tumors and tumor responses to radiation therapyMeth...
|
PDF Full Text Request