Objective: To investigate the prevalence and risk of thyroid incidentaloma identified by positron emission tomography/computed tomography (PET/CT). Study Design: Historical cohort study. Setting: Fudan University Shanghai Cancer Center. Methods: A total of 15 948 non-thyroid disease patients who underwent fluorine-18 fluorodeoxyglucose (F-18-FDG) PET/CT from November 2006 to September 2010 were included. They were divided into two groups: 12 080 patients for metastatic evaluation and 3868 patients for cancer screening. When thyroid incidentaloma was found, further diagnostic examination was conducted. Main Outcome Measures: Prevalence and risk of thyroid incidentaloma. Results: The prevalence of incidental thyroid F-18-FDG uptake was approximately 2.5% (395 of 15 948). The prevalence of incidentaloma in healthy subjects (118 of 3868; 3.1%) was statistically higher than that in patients with suspected or known cancer (277 of 12 080; 2.3%) (p < .05). Among 395 incidentalomas, 146 patients had further examinations (53 patients with histologic confirmations, 93 patients with clinical monitoring). Finally, 43 lesions were confirmed to be malignancies. Therefore, the cancer risk was 29.5% (43 of 146), and it was higher in cancer screening patients (24 of 59; 40.7%) than in alleged cancer patients (19 of 87; 21.8%) (p < .05). As for FDG uptake pattern, the prevalence of thyroid cancer was 11.6% (5 of 43) and 36.9% (38 of 103) in the group of patients with diffuse and focal uptake, respectively (p < .05). After logistic regression analysis, age, sex, maximal standardized uptake value, and calcification were the potent predictors of differentiation. Conclusion: The presence of focal uptake with high SUVmax and calcification detected on CT images correlates with a high likelihood of thyroid malignancy. When a focal thyroid incidentaloma is detected, further examination should be performed.
(8.0+极速模式)