The role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography whole body imaging in the evaluation of focal thyroid incidentaloma.
BACKGROUND
18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) is a non-invasive whole-body imaging technique used to evaluate various types of malignancies. Recent advances have rapidly developed it into a diagnostic imaging tool in oncology.


OBJECTIVE
In this study, the prevalence of thyroid incidentaloma and its cancer risk rate were investigated by 18F-FDG PET/CT. The threshold of maximal standardized uptake value (SUVmax) for differentiation of benign and malignant tumors was also defined.


METHODS
From June 2007 to December 2008, 3600 subjects underwent 18F-FDG PET/CT in our department. Among the population under study, 115 subjects developed focal increased 18F-FDG uptake as thyroid incidentalomas and their SUVmax were analyzed qualitatively and semi-quantitatively.


RESULTS
Data from the 18F-FDG PET/CT study suggested that overall prevalence of thyroid incidentaloma was 3.2% (115/3580). Among the 96 incidentalomas (20 confirmed by surgery; 76 confirmed by fine-needle aspiration) with additional cyto- and histopathological diagnoses, 50% were malignant thyroid lesions. Therefore, the cancer risk of thyroid incidentaloma was 50%. SUVmax values of the malignant samples were significantly higher than those of benign (p=0.00, p<0.05). A SUVmax above 8 tended to be malignant. A significant correlation between SUVmax and maximal diameter of the thyroid incidentaloma was also indicated.


CONCLUSIONS
Thyroid incidentaloma detected by 18FFDG PET/CT has higher risk rate for thyroid malignancy; SUVmax can be used for differentiating benign from malignant thyroid tumors.
Department of Nuclear Medicine, Rui Jin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200025, China.
G
G
Zhai
M
M
Zhang
H
H
Xu
C
C
Zhu
B
B
Li
D044963:Biopsy, Fine-Needle; D005260:Female; D019788:Fluorodeoxyglucose F18; D006651:Histocytochemistry; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D015995:Prevalence; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000473:pathology; D014057:Tomography, X-Ray Computed / Q000379:methods*; D051598:Whole Body Imaging / Q000379:methods
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18