| ObjectiveThe incidence of thyroid cancer has been increasing all around the world in the past decades. There are several types of thyroid cancer. About 90% of thyroid cancers are differentiated thyroid cancer(DTC) which consists primarily of papillary thyroid carcinoma(PTC) and follicular thyroid carcinoma(FTC). Currently, radioiodine therapy has been widely used for the treatment of thyroid carcinomas. During the 131 I treatment, about 10% of DTC patients demonstrated a weakening iodine uptake capacity, leading to a low efficiency of 131 I treatment. Either poorly differentiated thyroid carcinoma(p DTC) or loss of anaplastic thyroid cancer(ATC) is mostly from the loss differentiation of DTC. Once DTC progressed p DTC even ATC, the iodine uptake capacity would weaken as well as a decreasing sensitivity to radiotherapy and chemotherapy is gradually reduced. What’s more, a distant metastasis would occur, resulting in a worse prognosis. Therefore, it is particularly important to diagnose p DTC / ATC recurrence and distant metastasis as early as possible. However, at present, there is no ideal method to diagnose p DTC / ATC recurrence and distant metastases. The diagnostic efficacy of 18F-FDG DTC recurrence and metastases are greatly different and may be influenced by many factors. With the other positron imaging agents such as 18F-FCH and 18F–FMISO appearing, the current research on whether these imaging agents can improve the comprehensive diagnostic efficacy of PET/CT in p DTC / ATC is still rare. Therefore, my study is to make p DTC / ATC cell and animal model, have PET/CT imaging of variety positron agents and evaluate the comprehensive diagnostic performance of different positron imaging agents for p DTC / ATC, hoping to find better positron imaging agents for the comprehensive diagnostic efficacy of p DTC / ATC and to offer guidance for the further treatment. This paper consists of three partsPart one: The construction of p DTC / ATC added inflammation in animal models for the preparation of multiple positron tracers PET/CT. First, the human papillary thyroid carcinoma K1 cell lines were selected for this research. K1 cell lines were irradiated by Low dose iodine 131 to make p DTC / ATC cell model; p DTC / ATC K1 cell lines were implanted to the right flanks of nude mice subcutaneously and observe the tumor growth dynamically. After building p DTC / ATC in nude mice, the sterile turpentine was injected in the nude mice’s right thigh muscle to make p DTC / ATC added inflammation animal models.Part two: To study the biodistribution of multiple positron traces in nude mice with p DTC / ATC added inflammation, compare their biodistribution in tumor and inflammation to find the high specificity positron trace for the future PET/CT imaging. Analyze the mechanism of p DTC / ATC 18F-FCH absorbing. First, inject the tail vein by 18F-FDG, 18F-FCH and 18F-FMISO respectively in the nude mice. To kill the nude mice and analyze the biodistribution of these traces in bearing tumor nude mice 60 min, 30 min and 90 min after the tail vein injection of of 18F-FDG, 18F-FCH, and 18F-FMISO respectively. The Chok and Ch AT m RNA and protein expression levels of Nude p DTC / ATC tissue and normal thyroid tissue were measured by RT-PCR and Western Blot.Part three: To perform nude mice with implanted tumor and inflammation 18F-FDG, 18F-FCH and 18F-FIMSO PET/CT imaging in 60 min, 30 min and 90 min after the tail vein injection of 18F-FDG, 18F-FCH and 18F-FMISO respectively with Siemens Biograph Truepoint 64 PET/CT system. To compare the uptakes of 18F-FDG, 18F-FCH and 18F-FMISO in implanted tumor, inflammatory tissue and other organs, and evaluate the diagnostic efficacy of these traces in implanted tumor. To analyze the PET/CT imaging of 18F-FDG and 18F-FCH in a group of patients with p DTC / ATC and evaluate the comprehensive values of 18F-FDG, 18F-FCH PET/CT in p DTC / ATC. Materials and Methods 1. The construction and identification of p DTC / ATC added inflammation in animal models.K1 cell lines were irradiated by Low dose iodine 131 to made p DTC / ATC cell model; To implant p DTC / ATC K1 cell lines to the right flanks of nude mice subcutaneously and observe the tumor growth dynamically, After building p DTC / ATC in nude mice, injections the sterile turpentine in its right thigh muscle to made p DTC / ATC added inflammation in animal models.Human papillary thyroid carcinoma K1 cell lines were radiated by 740 k Bq compound 131 I solution in 0 h, 3 h, 6 h, 12 h, 24 h, 48 h and 72 h respectively. Radioactivity of cells in each group was measured by counting γ counter, and selecting fastest drops time point of cell count radioactive radiation. To evaluate proliferation effect of K1 cells after low-dose 131 I by colony formation assay. And to evaluate the differentiation degree changes in cells by the expression of TSHR, NIS and TPO with Western Blot.The p DTC / ATC K1 cell line was implanted to 45 nude mice(age:4~5 weeks, weight 13~16g) and the tumor growth was observed dynamically,and four weeks after transplantation, the nudes were injected sterile turpentine inter right thigh muscle, and the swelling of right thighs were observed after injection 24 h. Then 6 nude mice were selected randomly and killed, and the implanted tumors and inflammation tissues were dissected and histopathological slices were made to observe the tumor cells.2.The research of biodistribution and PET imaging of multiple positron traces in nude mice implanted tumor. And preliminary study was made on the mechanism of tumor tissue uptake of choline. 18 nude mice with implanted tumor were divided into 3 groups randomly, 9nude mice in every group. Group FDG were killed 60 min and Group FCH were killed30min after the tail vein injection of 18F-FDG, 18F-FCH respectively, and groupFMISO were killed 90 min post injection of 18F-FMISO, and the tumors,inflammation tissue and other normal organs and tissues were dissected, the uptake(%ID/g) of tumors and normal organs or tissues were measured and the ratios ofuptake(%ID/g) of tumors to normal organs or tissues were compared. The Chok andCh AT m RNA and protein expression levels of Nude p DTC / ATC tissue and normalthyroid tissue were measured by RT-PCR and Western Blot.3.The research of PET imaging of multiple positron traces in nude miceimplanted tumor. And the clinical application of multiple positron tracersPET/CT in the p DTC / ATC patients.27 nude mice with implanted tumor were divided into 3 groups random, groupFDG, FCH and FMISO, 9 nude mice in every group, group FDG perform 18F-FDGPET/CT, group FCH perform18F-FCH PET/CT, and group FMISO perform18F-FMISO PET/CT. The mean standard uptake values(SUVmean) of tumor,inflammation tissue and other normal organs or tissues and the ratios of meanstandard values of tumor to other normal organs or tissues were calculated andcompared.All the imaging results of a group of patients underwent 18F-FDG, and 18F-FCHPET/CT from September 2012 to September 2013 was analyzed retrospectively. All21 patients performed 18F-FDG and 18F-FCH PET/CT. All the imaging were visualinspected and analyzed semi-quantitatively, and the maximum standard uptake valuesof thyroid primary lesions, regional lymph nodes and distal metastasis of 2 kinds ofpositron tracers PET/CT were measured and compared, and the sensitivities andspecificities of different tracers PET/CT in diagnosing regional lymph nodes werealso calculated and compared.4.Statistically analysisSPSS19.0 software bag was selected, and the differences of mean of different groups were analyzed with paired t test, and the differences of rates of different groups were analyzed with chi-square test. Results1. The construction and identification of p DTC / ATC added inflammation in animal models.The rate of tumor construction was 100 percent. The tumor nodule was about 5 millimeters in diameter 14 days after the implantation of k1 cell line to the right flanks of 45 nude mice, and tumor volume was more than 50 cubic millimeters. A rapid growth was observed from the 3rd week, and the tumor volume was above 500 cubic millimeters and the diameter of nodule was about 18 mm were observed. The shape of implanted tumor was round, egg-shaped in the early stage, but irregular shape with uneven surface and multinodular confluent was observed in the late stage. The skin temperature increased in inflammation area of the right thigh. And a lot of neutrophil infiltrations were found in muscle tissue in the microscope.2. The biodistribution and PET/CT results of 3 kinds of positron tracers in nude mice bearing implanted tumor. And preliminary study was made on the mechanism of tumor tissue uptake of choline.The biodistribution of 3 kinds of positron tracers in nude mice bearing implanted tumor. The most radioactivities(%ID/g) of 18F-FDG were found in tumor, and the second was found in myocardium, and then the kidney, inflammatory tissue and spleen, and the least was found in blood and muscles. The most radioactivities(%ID/g) of 18F-FCH were found in liver, and the second was found in kidney, and then the tumor, and the least was found in heart, inflammatory tissue and muscles. The most radioactivities(%ID/g) of 18F-FMISO were found in kidney, and the second was found in liver, and then the heart, and the least was found in tumor, inflammatory tissue and muscles. All the ratios of uptakes(%ID/g) of 18F-FDG and 18F-FCH in tumors to those of blood, muscles and lung were more than 2. The uptake(%ID/g) of 18F-FDG in implanted tumor is higher than those of 18F-FCH and 18F-FMISO and there were statistically differences between those of 18F-FDG and 18F-FCH, and between those of 18F-FDG and 18F-FMISO, and all the p values were less than 0.05. There were statistically differences between all the uptakes(%ID/g) in other normal organs and ratios of uptakes(%ID/g) tumors to blood, muscles and lung of 18F-FDG and18F-FCH, and also between those of 18F-FDG and 18F-FMISO, and all the p values were less than 0.05.The Chok and Ch AT m RNA and protein were expressed in thyroid cancer tissue and normal thyroid tissue, and the expression of thyroid cancer was significantly increased than the normal control group.3. The research of PET imaging of multiple positron traces in nude mice implanted tumor. And the clinical application of multiple positron tracers PET/CT in the p DTC / ATC patients.PET/CT results of 3 kinds of positron tracers in nude mice bearing implanted tumor. The uptakes with different extent in implanted tumors and inflammatory tissues were observed. The tumors uptake of 18F-FDG is more than those of 18F-FCH, and the tumors are hardly uptake 18F-FMISO. The mean standard uptake values(SUVmean) of 18F-FDG, 18F-FCH and 18F-FMISO of tumor were 7.58, 3.19 and 1.05, respectively, and there were statistically differences among of them, and p value of less than0.001 were suggested respectively. The inflammatory tissues uptake of 18F-FDG is more than those of 18F-FCH and 18F-FMISO, there are no difference uptake between18F-FCH and 18F-FMISO. The mean standard uptake values(SUVmean) of 18F-FDG, 18F-FCH and 18F-FMISO of tumor were 4.11, 1.01 and 0.95,respectively, and there were statistically differences between 18F-FDG and 18F-FCH,or 18F-FDG and 18F-FMISO, and t values of 3.235, 6.138 and 10.21, and p value of less than 0.001, less than 0.001 and more than 0.05 were suggested respectively.All the imaging results of a group of patients underwent 18F-FDG, and 18F-FCH PET/CT from September 2012 to September 2013 was analyzed. All 21 patients performed 18F-FDG PET/CT and 18F-FCH PET/CT. 13/21 cases were positive in 18F-FDG PET / CT imaging, and 7 cases were negative. The overall sensitivity, specificity, positive predictive value and negative predictive value were were 88.9%, 58.3%, 50% and 71.4% of 18F-FDG PET / CT imaging respectively. 6/21 cases were positive in 18F-FCH PET/CT imaging, and 15 cases were negative. The overall sensitivity, specificity, positive predictive value and negative predictive value were were 55.6%, 91.7%, 83.3% and 73.3% of 18F-FCH PET / CT imaging respectively. Conclusions1.The p DTC / ATC animal model constructed by K1 cell lines irradiated by low-dose iodine 131 is to some extent the model of dedifferentiation of papillary thyroid carcinoma in the process of iodine 131 ablation. The thyroid characteristic protein expression and proliferation in this model was also in accordance with the property of thyroid carcinoma developed to poor differentiation. Subcutaneous inoculation K1 cell lines with low-dose iodine 131 radiation and the injection of sterile turpentine in the thigh muscle can get a poor dedifferentiation of thyroid cancer added inflammation in animal models.2.The p DTC / ATC 18F-FCH PET / CT imaging has relationship with Chok and Ch AT m RNA and protein overexpression in tumor cells, suggesting that not only the onphosphorylation pathway was activated but also choline acetyltransferase was participation in p DTC / ATC.3.In the diagnosis of p DTC / ATC 18F-FDG PET / CT has the higher sensitivity, while 18F-FCH has the higher specificity of the ATC. 18F-FCH may be a useful complement to 18F-FDG PET / CT imaging. The combination of 18F-FCH PET / CT and 18F-FDG PET / CT can improve the accuracy of p DTC / ATC diagnosis.4. Compared with 18F-FDG PET/CT and 18F-FCH PET/CT, 18F-FMISO PET/CT is uncompetitive in diagnosing p DTC / ATC recurrence or metastasis. |
