Focal uptake of fluorodeoxyglucose by the thyroid in patients undergoing initial disease staging with combined PET/CT for non-small cell lung cancer.
OBJECTIVE
To retrospectively evaluate the prevalence of focal fluorodeoxyglucose (FDG) uptake by the thyroid gland on combined positron emission tomographic (PET) and computed tomographic (CT) scans in patients undergoing staging of newly diagnosed non-small cell lung cancer (NSCLC).


METHODS
Institutional review board approval was obtained, informed consent was waived, and the study was Health Insurance Portability and Accountability Act-compliant. Whole-body PET/CT scans and medical records of 140 consecutive patients with newly diagnosed NSCLC (80 men, 60 women; mean age, 66 years; range, 39-89 years) were retrospectively reviewed by two experienced PET/CT scan readers. Maximum standardized uptake value (SUV) was calculated for FDG-avid thyroid foci. Corresponding thyroid CT findings were recorded in patients with focal increased FDG thyroid uptake.


RESULTS
PET results showed that six patients (4.3%) had seven foci of increased FDG uptake in the thyroid. Five of the seven foci (in four patients) corresponded to a low-attenuation thyroid lesion on the non-enhanced CT scan. Lesions ranged in diameter from 0.8 to 2.5 cm. Four of the lesions were found to be papillary thyroid cancers at fine-needle aspiration biopsy. The fifth lesion was found to be benign at thyroidectomy. The remaining two patients did not have histologic confirmation of their thyroid lesion because no specific biopsy site was visualized on CT or sonographic images and lesions were considered benign. Maximum SUV of the thyroid cancers ranged from 3.0 to 32.9 (mean, 13.7). Maximum SUV of benign thyroid lesions ranged from 4.6 to 6.2 (mean, 5.4).


CONCLUSIONS
Focal thyroid FDG uptake found during the initial staging of NSCLC at PET/CT indicates a high likelihood of primary thyroid cancer.
Department of Radiology, Division of Diagnostic Imaging, University of Texas M. D. Anderson Cancer Center, Box 57, 1515 Holcombe Blvd, Houston, TX 77030, USA.
Jeong Geun
JG
Yi
Edith M
EM
Marom
Reginald F
RF
Munden
Mylene T
MT
Truong
Homer A
HA
Macapinlac
Gregory W
GW
Gladish
Bradley S
BS
Sabloff
Donald A
DA
Podoloff
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis / Q000000981:diagnostic imaging; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011859:Radiography; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging*; D014055:Tomography, Emission-Computed
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18