ABSTRACT
Objective To investigate the 18F-FDG PET/CT features of medullary thyroid carcinoma (MTC), and to improve its diagnosis preoperatively.Methods Data of 18F-FDG PET/CT findings and clinical materials of 7 patients with MTC confirmed by pathology were retrospectively analyzed. SUVmaxEand SUVmaxDwere measured in primary tumor, and retention index(RI)was calculated.Results There were four patients with single lesion,two patients with double lesions, one patient with multiple lesions,four patients with lesions of irregular shape,four patients with lesions of unclear border, seven patients with lesions of uneven decreased density and five patients with calcifications in lesions.Uptake of 18F-FDG in primary tumor was lower in 2 patients,their SUVmaxEvalues were 2.5 and 2.1 respectively,and RI values were-20% and-14.3% respectively.The other five patients showed higher metabolism in both early and delayed imaging,and SUVmaxEwas 3.6-9.1 with an average of 5.8±2.1.RI was 7.5%-45.8% with the average of 21.3%±16.2%.There were five patients with cervical lymph node metastasis.The high metabolism was found in both early and delayed imaging of FDG.The ranges of SUVmaxEand SUVmaxDwere 3.2-8.2 and 3.3-9.8 respectively.None of 7 patients showed distant metastasis.Conclusion 18F-FDG PET/CT is helpful for identifying MTC and providing information about biological behavior and evaluating metastasis of MTC.
ABSTRACT
Objective To study the effect of time delay on tumor-immune system in tumor growth through theoretical approaches. Methods A mathematical model of the tumor-immune system interactions was established, and a time delay in the logistic growth term was introduced to investigate the processes of the interaction between immune system and tumor cells through qualitative analysis and numerical simulations. The relationship between the states of tumor and time delay was analyzed and the results were compared with the stages of the cancer immunoediting. Results Qualitative analysis and numerical simulations indicated that the tumor-immune system was a stable equilibrium state if the time delay was small. With the time delay increasing, the tumor-immune system entered equilibrium and escape stages of the cancer immunoediting, which described the alteration from dormant state to malignant state. Conclusions The time delay plays a key role in the interaction between immune system and tumor cells. The different time delays can result in different behaviors of tumor. The results will help to deepen clinical understanding of the tumor-immune system and provide references for the analysis and treatment of tumor.