Thyroid incidentalomas identified by 18F-FDG PET: sonographic correlation.
OBJECTIVE
The purpose of this study was to evaluate the risk of malignancy of thyroid incidentalomas detected on (18)F-FDG PET and the diagnostic accuracy of sonography for differentiating benign from malignant focal thyroid incidentalomas that were detected on FDG PET.


METHODS
Retrospective review was performed of a database of 87 focal thyroid lesions seen on FDG PET and sonography. Forty-two focal lesions were malignant. We compared the accuracy of the maximum standard uptake value (SUV) to differentiate benign from malignant thyroid lesions. We classified the thyroid nodules as probably benign or suspicious for malignancy by the sonographic features. Statistical analyses compared two subgroups by sonographic classifications between benign and malignant thyroid lesions.


RESULTS
The maximum SUV of the malignant nodules was not significantly higher than that of benign lesions. Thirty-seven (75.5%) of 49 lesions with suspicious sonographic findings revealed malignancy on cytopathology, compared with five (13.2%) of 38 lesions that showed probably benign sonographic findings. These differences were statistically significant using a kappa test (kappa = 0.675, p = 0.001) and logistic regression (odds ratio = 26.2, p = 0.001).


CONCLUSIONS
The probability (48.3%) of malignancy of focal thyroid incidentalomas seen on FDG PET is high. The maximum SUV of thyroid cancer is not significantly higher than that of benign lesions. The probability (13.2%) of malignancy is much lower when the sonographic findings appear benign, as compared with a significantly higher probability (75.5%) of malignancy when the sonographic findings are suspicious for malignancy.
Kwak
Jin Young
JY
Department of Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, 250 Seongsanno (134 Sinchon-dong), Seodaemun-gu, Seoul 120-752, Korea.
Kim
Eun-Kyung
EK
Yun
Mijin
M
Cho
Arthur
A
Kim
Min Jung
MJ
Son
Eun Ju
EJ
Oh
Ki Keun
KK
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044963:Biopsy, Fine-Needle; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D033162:Incidental Findings; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging*; D014055:Tomography, Emission-Computed; D018084:Ultrasonography, Interventional
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18