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.